bugfixes and translation

Я без шуток не хожу -
То комменты не коммичу,
То весь класс перепишу

Кволити - не кволити,
Хуй меня уволите

app/build.gradle.kts

@@ -50,13 +50,16 @@ dependencies {
     implementation(libs.androidx.activity)
     implementation(libs.androidx.legacy.support.v4)
     implementation(libs.androidx.fragment)
+    implementation(libs.androidx.material3.android)
     testImplementation(libs.junit)
     implementation(libs.volley)
     androidTestImplementation(libs.androidx.junit)
     implementation(libs.zxing.android.embedded)
     implementation("com.google.zxing:core:3.4.1")
     androidTestImplementation(libs.androidx.espresso.core)
-
+    implementation("com.google.android.material:material:1.3.0-alpha03")
+    implementation(libs.androidx.security.crypto)
+    implementation(libs.okhttp)
     // Barcode scanning API
     implementation (libs.barcode.scanning)
 

app/src/main/AndroidManifest.xml

@@ -13,6 +13,7 @@
     <uses-permission android:name="android.permission.READ_MEDIA_VIDEO"/>
     <uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE"/>
     <uses-permission android:name="android.permission.INTERNET"/>
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
 
     <application
             android:allowBackup="true"
@@ -48,6 +49,34 @@
                 android:name=".activities.FindBarcodelessAbstractProduct"
                 android:exported="false"
                 android:theme="@style/Theme.BarcodeScannerForEmployees"/>
+        <activity
+                android:name=".activities.MainActivity"
+                android:exported="false"
+                android:theme="@style/Theme.BarcodeScannerForEmployees"/>
+        <activity
+                android:name=".activities.LoginActivity"
+                android:exported="false"
+                android:theme="@style/Theme.BarcodeScannerForEmployees"/>
+        <activity
+                android:name=".activities.AccountSettingsActivity"
+                android:exported="false"
+                android:theme="@style/Theme.BarcodeScannerForEmployees"/>
+        <activity
+                android:name=".activities.GroupActivity"
+                android:exported="false"
+                android:theme="@style/Theme.BarcodeScannerForEmployees"/>
+        <activity
+                android:name=".activities.ManageGroupActivity"
+                android:exported="false"
+                android:theme="@style/Theme.BarcodeScannerForEmployees"/>
+        <activity
+                android:name=".activities.MyGroupsActivity"
+                android:exported="false"
+                android:theme="@style/Theme.BarcodeScannerForEmployees"/>
+        <activity
+                android:name=".activities.SettingsActivity"
+                android:exported="false"
+                android:theme="@style/Theme.BarcodeScannerForEmployees"/>
         <activity
                 android:name=".activities.FullscreenActivity"
                 android:configChanges="orientation|keyboardHidden|screenSize"
@@ -61,7 +90,7 @@
         
         <provider
                 android:name="androidx.core.content.FileProvider"
-                android:authorities="com.google.firebase.components.activities.MainActivity.provider;com.google.firebase.components.activities.FullscreenActivity.provider;com.google.firebase.components.activities.AddAbstractProductActivity.provider;com.google.firebase.components.activities.AddProductActivity.provider;com.google.firebase.components.activities.ExpiryCalendarActivity.provider;com.google.firebase.components.activities.FindBarcodelessAbstractProduct.provider;com.google.firebase.components.activities.ExpiryCalendarGroupActivity.provider"
+                android:authorities="com.google.firebase.components.activities.MainActivity.provider;com.google.firebase.components.activities.FullscreenActivity.provider;com.google.firebase.components.activities.AddAbstractProductActivity.provider;com.google.firebase.components.activities.AddProductActivity.provider;com.google.firebase.components.activities.ExpiryCalendarActivity.provider;com.google.firebase.components.activities.FindBarcodelessAbstractProduct.provider;com.google.firebase.components.activities.ExpiryCalendarGroupActivity.provider;com.google.firebase.components.activities.AccountSettingsActivity.provider;com.google.firebase.components.activities.GroupActivity.provider;com.google.firebase.components.activities.SettingsActivity.provider"
                 android:exported="false"
                 android:grantUriPermissions="true">
             <meta-data
@@ -70,7 +99,7 @@
         </provider>
 
         <activity
-                android:name=".activities.MainActivity"
+                android:name=".activities.NavigatorActivity"
                 android:exported="true"
                 android:theme="@style/Theme.BarcodeScannerForEmployees">
             <intent-filter>

app/src/main/java/org/foxarmy/barcodescannerforemployees/DBStorageController.kt

@@ -1,326 +0,0 @@
-package org.foxarmy.barcodescannerforemployees
-
-import android.content.ContentValues
-import android.content.Context
-import android.database.DatabaseUtils
-import android.database.sqlite.SQLiteDatabase
-import android.database.sqlite.SQLiteOpenHelper
-import android.provider.BaseColumns
-import org.foxarmy.barcodescannerforemployees.dataclasses.AbstractProduct
-import org.foxarmy.barcodescannerforemployees.dataclasses.Product
-import java.io.File
-
-object AbstractProductContract {
-    object AbstractProductEntry : BaseColumns {
-        const val TABLE_NAME = "abstract_products"
-        const val BARCODE = "barcode"
-        const val PRODUCT_NAME = "name"
-        const val PRODUCT_NET_WEIGHT = "net_weight"
-        const val IMAGE_FILENAME = "image_filename"
-        const val CATEGORY = "category"
-        const val UNIT = "unit"
-    }
-}
-
-object CategoriesContract {
-    object CategoryEntry : BaseColumns {
-        const val TABLE_NAME = "categories"
-        const val CATEGORY_NAME = "category_name"
-    }
-}
-
-object ProductContract {
-    object ProductEntry : BaseColumns {
-        const val TABLE_NAME = "products"
-        const val ABSTRACT_PRODUCT_ID = "abstract_product_id"
-        const val AMOUNT = "amount"
-        const val DATE_OF_PRODUCTION = "date_of_production"
-        const val EXPIRY_DATE = "expiry_date"
-    }
-}
-
-const val SQL_CREATE_ABSTRACT_PRODUCTS_TABLE =
-    "CREATE TABLE ${AbstractProductContract.AbstractProductEntry.TABLE_NAME} (" +
-            "${BaseColumns._ID} INTEGER PRIMARY KEY," +
-            "${AbstractProductContract.AbstractProductEntry.BARCODE} TEXT," +
-            "${AbstractProductContract.AbstractProductEntry.PRODUCT_NAME} TEXT," +
-            "${AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT} REAL," +
-            "${AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME} TEXT," +
-            "${AbstractProductContract.AbstractProductEntry.CATEGORY} INTEGER," +
-            "${AbstractProductContract.AbstractProductEntry.UNIT} INTEGER)"
-
-const val SQL_CREATE_PRODUCTS_TABLE =
-    "CREATE TABLE ${ProductContract.ProductEntry.TABLE_NAME} (" +
-        "${BaseColumns._ID} INTEGER PRIMARY KEY," +
-        "${ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID} INTEGER," +
-        "${ProductContract.ProductEntry.AMOUNT} INTEGER," +
-        "${ProductContract.ProductEntry.DATE_OF_PRODUCTION} INTEGER," +
-        "${ProductContract.ProductEntry.EXPIRY_DATE} INTGER)"
-
-const val SQL_CREATE_CATEGORIES_TABLE =
-    "CREATE TABLE ${CategoriesContract.CategoryEntry.TABLE_NAME} (" +
-            "${BaseColumns._ID} INTEGER PRIMARY KEY," +
-            "${CategoriesContract.CategoryEntry.CATEGORY_NAME} TEXT)"
-
-class DBStorageController(context: Context) : SQLiteOpenHelper(context, DATABASE_NAME, null, DATABASE_VERSION) {
-
-    override fun onCreate(db: SQLiteDatabase) {
-        db.execSQL(SQL_CREATE_ABSTRACT_PRODUCTS_TABLE)
-        db.execSQL(SQL_CREATE_PRODUCTS_TABLE)
-        db.execSQL(SQL_CREATE_CATEGORIES_TABLE)
-    }
-
-    override fun onUpgrade(db: SQLiteDatabase?, oldV: Int, newV: Int) {
-        TODO("Not yet implemented")
-    }
-
-    fun eraseCategory (db: SQLiteDatabase, id: Int, context: Context) {
-        val productsInCategory = getAllAbstractProductInCategory(db, id)
-
-        for (product in productsInCategory.iterator()) {
-            eraseAbstractProduct(db, product.id, context)
-        }
-
-        db.delete(CategoriesContract.CategoryEntry.TABLE_NAME, BaseColumns._ID + "=" + id, null)
-    }
-
-    fun getCategoryNameById(db: SQLiteDatabase, id: Int) : String {
-        var result = ""
-
-        val projection = arrayOf(CategoriesContract.CategoryEntry.CATEGORY_NAME)
-        val selection = "${BaseColumns._ID} = ?"
-        val selectionArgs = arrayOf(id.toString())
-
-        val cursor = db.query(CategoriesContract.CategoryEntry.TABLE_NAME, projection, selection, selectionArgs, null, null, null)
-
-        with (cursor) {
-            while (moveToNext()) {
-                result = getString(getColumnIndexOrThrow(CategoriesContract.CategoryEntry.CATEGORY_NAME))
-            }
-        }
-
-        return result
-    }
-
-    fun getAllAbstractProductInCategory(db: SQLiteDatabase, id: Int) : List<AbstractProduct> {
-
-        var result = mutableListOf<AbstractProduct>()
-        val projection = arrayOf(
-            BaseColumns._ID,
-            AbstractProductContract.AbstractProductEntry.BARCODE,
-            AbstractProductContract.AbstractProductEntry.PRODUCT_NAME,
-            AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME,
-            AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT,
-            AbstractProductContract.AbstractProductEntry.UNIT
-        )
-
-        val selection = "${AbstractProductContract.AbstractProductEntry.CATEGORY} = ?"
-        val selectionArgs = arrayOf(id.toString())
-
-        val cursor = db.query(AbstractProductContract.AbstractProductEntry.TABLE_NAME, projection, selection, selectionArgs, null, null, null)
-
-        with(cursor) {
-            while (moveToNext()) {
-                val abstractProductId = getInt(getColumnIndexOrThrow(BaseColumns._ID))
-                val abstractProductBarcode = getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.BARCODE))
-                val abstractProductName = getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NAME))
-                val abstractProductNetWeight = getDouble(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT))
-                val abstractProductImageHash = getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME))
-                val abstractProductUnit = getInt(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.UNIT))
-
-                val abstractProduct = AbstractProduct(abstractProductId, abstractProductBarcode, abstractProductName, abstractProductNetWeight, abstractProductImageHash, category = id, abstractProductUnit)
-
-                result.add(abstractProduct)
-            }
-        }
-
-        return result
-    }
-
-    fun getAmountOfAbstractProductsInCategory(db:SQLiteDatabase, id: Int) : Int {
-        return DatabaseUtils.longForQuery(db, "SELECT COUNT(*) FROM ${AbstractProductContract.AbstractProductEntry.TABLE_NAME} WHERE ${AbstractProductContract.AbstractProductEntry.CATEGORY} = ?", arrayOf(id.toString())).toInt()
-    }
-    fun eraseAbstractProduct(db: SQLiteDatabase, id: Int, context: Context) {
-        val projectionForAbstractProduct = arrayOf(
-            AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME
-        )
-
-        val selectionForAbstractProduct = "${BaseColumns._ID} = ?"
-        val selectionArgsForAbstractProduct = arrayOf(id.toString())
-        val cursorForAbstractProduct = db.query(
-            AbstractProductContract.AbstractProductEntry.TABLE_NAME,
-            projectionForAbstractProduct,
-            selectionForAbstractProduct,
-            selectionArgsForAbstractProduct,
-            null,
-            null,
-            null
-        )
-        var imageHash: String = ""
-
-        with (cursorForAbstractProduct) {
-            while(moveToNext()) {
-                val productImageHash = getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME))
-                imageHash = productImageHash
-            }
-        }
-        val picturesDir = File(context.filesDir, "pictures")
-        val thumbnailsDir = File(context.cacheDir, "thumbnails")
-
-        File(picturesDir, "$imageHash.png").delete()
-        File(thumbnailsDir, "$imageHash.webp").delete()
-
-        val projectionForProducts = arrayOf(BaseColumns._ID)
-        val selectionForProducts = "${ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID} = ?"
-        val selectionArgsForProducts = arrayOf(id.toString())
-
-        val cursorForProducts = db.query(ProductContract.ProductEntry.TABLE_NAME, projectionForProducts, selectionForProducts, selectionArgsForProducts, null, null, null)
-
-        with (cursorForProducts) {
-            while(moveToNext()) {
-                eraseProduct(db, getInt(getColumnIndexOrThrow(BaseColumns._ID)))
-            }
-        }
-
-        db.delete(AbstractProductContract.AbstractProductEntry.TABLE_NAME, BaseColumns._ID + "=" + id, null)
-    }
-
-    fun eraseProduct(db:SQLiteDatabase, id: Int) {
-        db.delete(ProductContract.ProductEntry.TABLE_NAME, BaseColumns._ID + "=" + id, null)
-    }
-
-    fun insertNewProduct(db: SQLiteDatabase, product: Product) {
-        val values = ContentValues().apply {
-            put(ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID, product.abstractProductId)
-            put(ProductContract.ProductEntry.AMOUNT, product.amount)
-            put(ProductContract.ProductEntry.DATE_OF_PRODUCTION, product.dateOfProduction)
-            put(ProductContract.ProductEntry.EXPIRY_DATE, product.dateOfExpiry)
-        }
-
-        db.insert(ProductContract.ProductEntry.TABLE_NAME, null, values)
-    }
-
-    fun findAmountOfProductsWithExpiryDate(db: SQLiteDatabase, date: Long): Int {
-        var amount = 0
-
-        val projection = arrayOf(
-            ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID,
-            ProductContract.ProductEntry.AMOUNT,
-            ProductContract.ProductEntry.DATE_OF_PRODUCTION,
-        )
-
-        val selection = "${ProductContract.ProductEntry.EXPIRY_DATE} = ?"
-        val selectionArgs = arrayOf(date.toString())
-
-        val cursor = db.query(ProductContract.ProductEntry.TABLE_NAME, projection, selection, selectionArgs, null, null, null)
-
-        with(cursor) {
-            while (moveToNext()) {
-                amount++
-            }
-        }
-
-        return amount
-    }
-
-    fun findAllExpiryDates(db:SQLiteDatabase): Set<Long> {
-        val dates: MutableSet<Long> = mutableSetOf<Long>()
-
-        val projection = arrayOf(
-            ProductContract.ProductEntry.EXPIRY_DATE
-        )
-
-        val orderBy = "${ProductContract.ProductEntry.EXPIRY_DATE} ASC"
-
-        val cursor = db.query(ProductContract.ProductEntry.TABLE_NAME, projection, null, null, null, null, orderBy)
-
-        with(cursor) {
-            while (moveToNext()) {
-                dates.add(getLong(getColumnIndexOrThrow(ProductContract.ProductEntry.EXPIRY_DATE)))
-            }
-        }
-
-        return dates
-    }
-
-    fun findAbstractProductByBarcode (db: SQLiteDatabase, barcode: String) : AbstractProduct? {
-        var abstractProduct: AbstractProduct? = null
-        val projection = arrayOf(
-            BaseColumns._ID,
-            AbstractProductContract.AbstractProductEntry.PRODUCT_NAME,
-            AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME,
-            AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT,
-            AbstractProductContract.AbstractProductEntry.CATEGORY,
-            AbstractProductContract.AbstractProductEntry.UNIT
-        )
-
-        val selection = "${AbstractProductContract.AbstractProductEntry.BARCODE} = ?"
-        val selectionArgs = arrayOf(barcode)
-
-        val cursor = db.query(AbstractProductContract.AbstractProductEntry.TABLE_NAME, projection, selection, selectionArgs, null, null, null)
-
-        with(cursor) {
-            while(moveToNext()) {
-                val id = getInt(getColumnIndexOrThrow(BaseColumns._ID))
-                val productName = getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NAME))
-                val imageFilename = getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME))
-                val netWeight = getDouble(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT))
-                val category = getInt(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.CATEGORY))
-                val unit = getInt(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.UNIT))
-
-                abstractProduct = AbstractProduct(id, barcode, productName, netWeight, imageFilename, category, unit)
-            }
-        }
-
-        return abstractProduct
-    }
-
-    fun findAbstractProductById(db: SQLiteDatabase, id: Int): AbstractProduct? {
-        var abstractProduct: AbstractProduct? = null
-        val projection = arrayOf(
-            BaseColumns._ID,
-            AbstractProductContract.AbstractProductEntry.PRODUCT_NAME,
-            AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT,
-            AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME,
-            AbstractProductContract.AbstractProductEntry.CATEGORY,
-            AbstractProductContract.AbstractProductEntry.BARCODE,
-            AbstractProductContract.AbstractProductEntry.UNIT
-        )
-
-        val selection = "${BaseColumns._ID} = ?"
-        val selectionArgs = arrayOf(id.toString())
-
-        val cursor = db.query(AbstractProductContract.AbstractProductEntry.TABLE_NAME, projection, selection, selectionArgs, null, null, null)
-
-        with (cursor) {
-            while (moveToNext()) {
-                val productId = getInt(getColumnIndexOrThrow(BaseColumns._ID))
-                val barcode = getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.BARCODE))
-                val name = getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NAME))
-                val netWeight = getDouble(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT))
-                val imageHash = getString((getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME)))
-                val category = getInt(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.CATEGORY))
-                val unit = getInt(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.UNIT))
-
-                abstractProduct = AbstractProduct(productId, barcode, name, netWeight, imageHash, category, unit)
-            }
-        }
-
-        return abstractProduct
-    }
-
-    fun updateProduct(db: SQLiteDatabase, product: Product) {
-        val values = ContentValues().apply {
-            put(ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID, product.abstractProductId)
-            put(ProductContract.ProductEntry.AMOUNT, product.amount)
-            put(ProductContract.ProductEntry.DATE_OF_PRODUCTION, product.dateOfProduction)
-            put(ProductContract.ProductEntry.EXPIRY_DATE, product.dateOfExpiry)
-        }
-        db.update(ProductContract.ProductEntry.TABLE_NAME, values, "${BaseColumns._ID} = ?", arrayOf(product.id.toString()))
-    }
-
-    companion object {
-        const val DATABASE_VERSION = 1
-        const val DATABASE_NAME = "database.db"
-    }
-}

app/src/main/java/org/foxarmy/barcodescannerforemployees/LoadingDialog.kt

@@ -0,0 +1,14 @@
+package org.foxarmy.barcodescannerforemployees
+
+import android.app.Dialog
+import android.os.Bundle
+import androidx.fragment.app.DialogFragment
+
+class LoadingDialog : DialogFragment() {
+    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
+
+
+
+        return super.onCreateDialog(savedInstanceState)
+    }
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/Net.kt

@@ -0,0 +1,662 @@
+package org.foxarmy.barcodescannerforemployees
+
+import android.content.Context
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import okhttp3.*
+import okhttp3.MediaType.Companion.toMediaType
+import okhttp3.MediaType.Companion.toMediaTypeOrNull
+import okhttp3.RequestBody.Companion.asRequestBody
+import org.foxarmy.barcodescannerforemployees.dataclasses.AbstractProduct
+import org.foxarmy.barcodescannerforemployees.dataclasses.Category
+import org.foxarmy.barcodescannerforemployees.dataclasses.Product
+import java.io.File
+import java.io.FileOutputStream
+import java.io.IOException
+import java.util.concurrent.TimeUnit
+
+class Net {
+    var language = "en-US"
+    var server = "bsfe.foxarmy.org"
+    var token = ""
+
+    fun serverIsAvailable(context: Context, callback: (Boolean) -> Unit) {
+        if (!isInternetConnectionAvailable(context)) {
+            callback(false)
+        }
+        CoroutineScope(Dispatchers.IO).launch {
+            var flag = false
+            val client = OkHttpClient();
+            val request = Request.Builder()
+                .url("https://$server/status")
+                .get()
+                .build();
+
+            try {
+                val response = client.newCall(request).execute();
+                flag = response.code == 200;
+            } catch (e: Exception) {
+                flag = false;
+            }
+            callback(flag)
+        }
+    }
+
+    fun requestProductFromOnlineDB(barcode: String, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+            val url = "https://ean-online.ru/match.php"
+
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+                .add("barcode", barcode)
+                .build()
+
+            val request = Request.Builder()
+                .url(url)
+                .post(body)
+                .addHeader("referer", "https://ean-online.ru")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun registerAccount(username: String, password: String, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+                .add("username", username)
+                .add("password", password)
+                .build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/user/register")
+                .post(body)
+                .addHeader("content-type", "application/x-www-form-urlencoded")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun login(username: String, password: String, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+                .add("username", username)
+                .add("password", password)
+                .build()
+            val requestLogin = Request.Builder()
+                .url("https://$server/api/user/login")
+                .post(body)
+                .addHeader("content-type", "application/x-www-form-urlencoded")
+                .addHeader("accept-language", language)
+                .build()
+            response = client.newCall(requestLogin).execute()
+            callback(response)
+        }
+    }
+
+    fun uploadAbstractProduct(
+        groupId: Int,
+        abstractProduct: AbstractProduct,
+        imageFile: File,
+        callback: (Response) -> Unit,
+    ) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val body = MultipartBody.Builder()
+                .setType("multipart/form-data".toMediaType())
+                .addFormDataPart("file", imageFile.name, imageFile.asRequestBody("image/png".toMediaTypeOrNull()))
+                .addFormDataPart("groupId", groupId.toString())
+                .addFormDataPart("localId", abstractProduct.id.toString())
+                .addFormDataPart("barcode", abstractProduct.barcode)
+                .addFormDataPart("name", abstractProduct.name)
+                .addFormDataPart("net_weight", abstractProduct.netWeight.toString())
+                .addFormDataPart("category", abstractProduct.category.toString())
+                .addFormDataPart("unit", abstractProduct.unit.toString())
+                .build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/abstractproduct/create")
+                .post(body)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun changeUsername(newUsername: String, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+            body.add("username", newUsername)
+
+            val requestBody = body.build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/user/changeUsername")
+                .post(requestBody)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun changePassword(newPassword: String, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+            body.add("password", newPassword)
+
+            val requestBody = body.build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/user/changePassword")
+                .post(requestBody)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun createGroup(name: String, password: String, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+
+            val requestBody = body.build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/group/create/$name")
+                .post(requestBody)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+            val response = client.newCall(request).execute()
+
+            changeGroupPassword(name, password, { responseFromPassword ->
+                callback(response)
+            })
+
+        }
+    }
+
+    fun joinGroup(id: Int, password: String, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+                .add("password", password)
+                .build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/group/join/$id")
+                .post(body)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun changeGroupPassword(name: String, password: String, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            getGroupId(name, { groupId ->
+                val client = OkHttpClient()
+
+                val body = FormBody.Builder()
+                body.add("password", password)
+
+                val requestBody = body.build()
+
+                val request = Request.Builder()
+                    .url("https://$server/api/group/password/$groupId")
+                    .post(requestBody)
+                    .addHeader("Authorization", "Bearer $token")
+                    .addHeader("accept-language", language)
+                    .build()
+                response = client.newCall(request).execute()
+                callback(response)
+            });
+        }
+    }
+
+    fun getGroupId(name: String, callback: (String) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/group/byName/$name")
+                .get()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+            response = client.newCall(request).execute()
+            callback(response.body!!.string())
+        }
+    }
+
+    fun getGroupName(id: Int, callback: (String) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/group/byId/$id")
+                .get()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+            response = client.newCall(request).execute()
+            callback(response.body!!.string())
+        }
+    }
+
+    fun getUsersInGroup(groupId: Int, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/group/getUsers/$groupId")
+                .get()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun getMyGroups(callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/user/myGroups")
+                .get()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun getUsernameById(userId: Int, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/user/byId/$userId")
+                .get()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun getGroupAdminId(groupId: Int, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/group/adminId/$groupId")
+                .get()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun updateAbstractProduct(
+        groupId: Int,
+        abstractProduct: AbstractProduct,
+        imageFile: File,
+        callback: (Response) -> Unit,
+    ) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val body = MultipartBody.Builder()
+                .setType("multipart/form-data".toMediaType())
+                .addFormDataPart("file", imageFile.name, imageFile.asRequestBody("image/png".toMediaTypeOrNull()))
+                .addFormDataPart("groupId", groupId.toString())
+                .addFormDataPart("localId", abstractProduct.id.toString())
+                .addFormDataPart("barcode", abstractProduct.barcode)
+                .addFormDataPart("name", abstractProduct.name)
+                .addFormDataPart("net_weight", abstractProduct.netWeight.toString())
+                .addFormDataPart("category", abstractProduct.category.toString())
+                .addFormDataPart("unit", abstractProduct.unit.toString())
+                .build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/abstractproduct/update")
+                .post(body)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun uploadCategory(groupId: Int, category: Category, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+                .add("localId", category.id.toString())
+                .add("categoryName", category.name)
+                .add("groupId", groupId.toString())
+                .build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/category/create")
+                .post(body)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun updateCategory(groupId: Int, category: Category, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+                .add("localId", category.id.toString())
+                .add("categoryName", category.name)
+                .add("groupId", groupId.toString())
+                .build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/category/update")
+                .post(body)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun uploadProduct(groupId: Int, product: Product, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+                .add("localId", product.id.toString())
+                .add("groupId", groupId.toString())
+                .add("abstract_product_id", product.abstractProductId.toString())
+                .add("amount", product.amount.toString())
+                .add("date_of_production", product.dateOfProduction.toString())
+                .add("expiry_date", product.dateOfExpiry.toString())
+                .build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/product/create")
+                .post(body)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun updateProduct(groupId: Int, product: Product, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+                .add("localId", product.id.toString())
+                .add("groupId", groupId.toString())
+                .add("abstract_product_id", product.abstractProductId.toString())
+                .add("amount", product.amount.toString())
+                .add("date_of_production", product.dateOfProduction.toString())
+                .add("expiry_date", product.dateOfExpiry.toString())
+                .build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/product/update")
+                .post(body)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun synchronize(groupId: Int, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/user/synchronize/$groupId")
+                .get()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun downloadImage(url: String, file: File, callback: () -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            val client = OkHttpClient.Builder()
+                .connectTimeout(30, TimeUnit.SECONDS)
+                .readTimeout(10, TimeUnit.MINUTES)
+                .build()
+
+            val request = Request.Builder()
+                .url(url)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            val response = client.newCall(request).execute()
+            if (!response.isSuccessful) throw IOException("Unexpected code $response")
+
+            val fos = FileOutputStream(file)
+
+            response.body?.byteStream()?.use { inputStream ->
+                fos.use {
+                    inputStream.copyTo(fos)
+                }
+            }
+            callback()
+        }
+    }
+
+    fun deleteCategory(groupId: Int, localId: Int, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/category/$groupId/$localId")
+                .delete()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun deleteAbstractProduct(groupId: Int, localId: Int, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/abstractproduct/$groupId/$localId")
+                .delete()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun deleteProduct(groupId: Int, localId: Int, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/product/$groupId/$localId")
+                .delete()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun renameGroup(groupId: Int, newName: String, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+                .add("name", newName)
+                .build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/group/rename/$groupId")
+                .post(body)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun transfer_ownership(groupId: Int, userId: Int, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+                .add("userId", userId.toString())
+                .build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/group/transferOwnership/$groupId")
+                .post(body)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+
+    fun leaveGroup(groupId: Int, callback: (Response) -> Unit) {
+        CoroutineScope(Dispatchers.IO).launch {
+            lateinit var response: Response
+
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/group/leave/$groupId")
+                .get()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+            callback(response)
+        }
+    }
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/Parser.kt

@@ -14,8 +14,6 @@ class Parser constructor() {
                 text = text.replace(found, "")
                 netWeight = stripNetWeight(found)
                 return Triple(text, netWeight, found)
-            } else {
-                return Triple(text, 0.0, "")
             }
         }
         return Triple("", 0.0, "")
@@ -48,4 +46,4 @@ class Parser constructor() {
 
         return AbstractProduct(0, "", name, netWeight, "", 0, unitNumber)
     }
-}
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/Requester.kt

@@ -1,40 +0,0 @@
-package org.foxarmy.barcodescannerforemployees
-
-import android.content.Context
-import android.widget.Toast
-import com.android.volley.toolbox.StringRequest
-import com.android.volley.toolbox.Volley
-
-class Requester constructor(var siteName: String, var endpoint: String) {
-    var response = ""
-
-    fun request(context: Context, barcode: String) {
-        val url = "${siteName}/${endpoint}"
-
-        val volleyQueue = Volley.newRequestQueue(context)
-        val stringRequest = object: StringRequest(
-            Method.POST, url, { resp ->
-            run {
-                response =
-                if (resp == "") {
-                    "Not found 404"
-                } else {
-                    resp
-                }
-            }
-        },
-            {
-                Toast.makeText(context, "Cannot make request", Toast.LENGTH_LONG).show()
-            }
-        ) {
-            override fun getHeaders(): Map<String, String> {
-                return mapOf("referer" to "$siteName/")
-            }
-
-            public override fun getParams(): MutableMap<String, String> {
-                return mutableMapOf("barcode" to barcode)
-            }
-        }
-        volleyQueue.add(stringRequest)
-    }
-}

app/src/main/java/org/foxarmy/barcodescannerforemployees/Utils.kt

@@ -3,22 +3,44 @@ package org.foxarmy.barcodescannerforemployees
 import android.app.Activity
 import android.content.Context
 import android.content.ContextWrapper
+import android.content.Intent
+import android.content.SharedPreferences
 import android.graphics.Bitmap
 import android.graphics.BitmapFactory
 import android.graphics.Matrix
+import android.media.ExifInterface
+import android.net.ConnectivityManager
+import android.net.NetworkCapabilities
 import android.net.Uri
 import android.os.Build
 import androidx.annotation.RequiresApi
+import androidx.appcompat.app.AlertDialog
 import androidx.core.content.FileProvider
+import androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
 import com.google.firebase.components.BuildConfig
+import org.foxarmy.barcodescannerforemployees.activities.LoginActivity
 import java.io.File
+import java.io.FileInputStream
 import java.io.FileOutputStream
-import java.net.URLEncoder
 import java.security.MessageDigest
+import java.text.SimpleDateFormat
 import java.util.*
+import kotlin.system.exitProcess
+
+fun convertToUnixEpochTimestamp(dateString: String): Long {
+    val format = SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'")
+    format.timeZone = TimeZone.getTimeZone("UTC")
+    val date = format.parse(dateString)
+    return date!!.time / 1000
+}
 
 fun getImageUri(activity: Activity, imageFile: File): Uri? {
-    return FileProvider.getUriForFile(activity, BuildConfig.APPLICATION_ID + "." + activity.localClassName + ".provider", imageFile)
+    return FileProvider.getUriForFile(
+        activity,
+        BuildConfig.APPLICATION_ID + "." + activity.localClassName + ".provider",
+        imageFile
+    )
 }
 
 @RequiresApi(Build.VERSION_CODES.R)
@@ -34,11 +56,18 @@ fun generateThumbnailForImage(context: Context, imageHash: String) {
     val imageContent = imageFile.inputStream().readBytes()
     var img = BitmapFactory.decodeByteArray(imageContent, 0, imageContent.size)
 
-    val matrix = Matrix();
-    matrix.postRotate(90f)
-    val scaled = Bitmap.createScaledBitmap(img, img.width/4, img.height/4, true)
-    val rotated = Bitmap.createBitmap(scaled, 0, 0, scaled.width, scaled.height, matrix, true)
-    rotated.compress(Bitmap.CompressFormat.WEBP_LOSSY, 25, FileOutputStream(thumbnailFile))
+    val exif = ExifInterface(imageFile.absoluteFile.toString())
+    val orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL)
+    val matrix = Matrix()
+
+    when (orientation) {
+        ExifInterface.ORIENTATION_ROTATE_90 -> matrix.postRotate(90F)
+        ExifInterface.ORIENTATION_ROTATE_180 -> matrix.postRotate(180F)
+        ExifInterface.ORIENTATION_ROTATE_270 -> matrix.postRotate(270F)
+    }
+    val rotated = Bitmap.createBitmap(img, 0, 0, img.width, img.height, matrix, true)
+    val scaled = Bitmap.createScaledBitmap(rotated, rotated.width / 4, rotated.height / 4, true)
+    scaled.compress(Bitmap.CompressFormat.WEBP_LOSSY, 25, FileOutputStream(thumbnailFile))
 }
 
 @OptIn(ExperimentalStdlibApi::class)
@@ -48,8 +77,11 @@ fun String.md5(): String {
     return digest.toHexString()
 }
 
-fun stripNetWeight (netWeight: String): Double {
-    return removeSubstringsFromString(netWeight, arrayOf("Л", "л", "мл", "Мл", "г", "Г", "кг", "Кг", "шт", "Шт", ",", " ", ".")).toDouble()
+fun stripNetWeight(netWeight: String): Double {
+    return removeSubstringsFromString(
+        netWeight,
+        arrayOf("Л", "л", "мл", "Мл", "г", "Г", "кг", "Кг", "шт", "Шт", ",", " ", ".")
+    ).toDouble()
 }
 
 fun removeSubstringsFromString(text: String, toRemove: Array<String>): String {
@@ -60,8 +92,6 @@ fun removeSubstringsFromString(text: String, toRemove: Array<String>): String {
     return result
 }
 
-fun String.utf8(): String = URLEncoder.encode(this, "UTF-8")
-
 fun getActivity(context: Context?): Activity? {
     if (context == null) {
         return null
@@ -85,13 +115,103 @@ fun calculateProductFreshness(dateOfProduction: Long, dateOfExpiry: Long): Doubl
     return lifeSpanLeft / productLifeSpan.toDouble()
 }
 
-fun getUnitNameById (context: Context, id: Int): String {
-    return when(id) {
+fun getUnitNameById(context: Context, id: Int): String {
+    return when (id) {
         0 -> { context.getString(R.string.kilogram) }
+
         1 -> { context.getString(R.string.gram) }
+
         2 -> { context.getString(R.string.liter) }
+
         3 -> { context.getString(R.string.milliliter) }
+
         4 -> { context.getString(R.string.pieces) }
+
         else -> { "" }
     }
 }
+
+fun parseIntArray(input: String): IntArray {
+    return input.trim('[', ']').split(",").map { it.trim().toInt() }.toIntArray()
+}
+
+fun parseStringList(input: String): List<String> {
+    return input.trim('[', ']').split(",").map { it.trim() }.toList()
+}
+
+fun calculateMd5Hash(file: File): String {
+    val digest = MessageDigest.getInstance("MD5")
+    val fis = FileInputStream(file)
+    val buffer = ByteArray(1024)
+    var bytesRead = fis.read(buffer)
+    while (bytesRead != -1) {
+        digest.update(buffer, 0, bytesRead)
+        bytesRead = fis.read(buffer)
+    }
+    fis.close()
+    return bytesToHex(digest.digest())
+}
+
+fun bytesToHex(bytes: ByteArray): String {
+    val hexString = StringBuilder()
+    for (byte in bytes) {
+        val hex = Integer.toHexString(0xff and byte.toInt())
+        if (hex.length == 1) {
+            hexString.append('0')
+        }
+        hexString.append(hex)
+    }
+    return hexString.toString()
+}
+
+fun isInternetConnectionAvailable(context: Context): Boolean {
+    if (context.getSystemService(Context.CONNECTIVITY_SERVICE) == null) return false
+    val connectivityManager =
+        context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
+    if (connectivityManager != null) {
+        val capabilities =
+            connectivityManager.getNetworkCapabilities(connectivityManager.activeNetwork)
+        if (capabilities != null) {
+            if (capabilities.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR)) {
+                return true
+            } else if (capabilities.hasTransport(NetworkCapabilities.TRANSPORT_WIFI)) {
+                return true
+            } else if (capabilities.hasTransport(NetworkCapabilities.TRANSPORT_ETHERNET)) {
+                return true
+            }
+        }
+    }
+    return false
+}
+
+fun noInternetConnectionAvailableNotification(context: Context) {
+    (context as Activity).runOnUiThread {
+        AlertDialog.Builder(context)
+            .setMessage(context.getString(R.string.no_internet_connection))
+            .setCancelable(false)
+            .setPositiveButton(R.string.quit) { _, _ ->
+                exitProcess(0)
+            }
+            .setNeutralButton(R.string.logout) { _, _ ->
+                val sharedPreferences = getPreferences(context)
+
+                sharedPreferences.edit().putString("token", "").apply()
+                sharedPreferences.edit().putString("server", "").apply()
+                sharedPreferences.edit().putStringSet("groups", emptySet()).apply()
+                sharedPreferences.edit().putString("currentGroup", "").apply()
+                val intent = Intent(context, LoginActivity::class.java)
+                context.startActivity(intent)
+                context.finish()
+            }.show()
+    }
+}
+
+fun getPreferences(context: Context): SharedPreferences {
+    return EncryptedSharedPreferences.create(
+        "sensitive",
+        MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+        context,
+        EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+        EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+    )
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/WebSocketClient.kt

@@ -0,0 +1,182 @@
+package org.foxarmy.barcodescannerforemployees
+
+import android.content.Context
+import android.os.Build
+import android.util.Log
+import androidx.annotation.RequiresApi
+import okhttp3.*
+import org.foxarmy.barcodescannerforemployees.activities.MainActivity
+import org.foxarmy.barcodescannerforemployees.database.AbstractProductDAO
+import org.foxarmy.barcodescannerforemployees.database.CategoryDAO
+import org.foxarmy.barcodescannerforemployees.database.DBStorageController
+import org.foxarmy.barcodescannerforemployees.database.ProductDAO
+import org.foxarmy.barcodescannerforemployees.dataclasses.AbstractProduct
+import org.foxarmy.barcodescannerforemployees.dataclasses.Category
+import org.foxarmy.barcodescannerforemployees.dataclasses.Product
+import org.json.JSONObject
+import java.io.File
+import java.util.concurrent.TimeUnit
+
+class WebSocketClient(private val context: Context, private val server: String) {
+
+    private lateinit var webSocket: WebSocket
+    private lateinit var token: String
+    private lateinit var currentGroup: String
+
+    fun connect(token: String, currentGroup: String) {
+        this.token = token
+        this.currentGroup = currentGroup
+
+        val client = OkHttpClient.Builder()
+            .connectTimeout(5, TimeUnit.SECONDS)
+            .readTimeout(1, TimeUnit.MINUTES)
+            .writeTimeout(10, TimeUnit.SECONDS)
+            .callTimeout(1, TimeUnit.MINUTES)
+            .build()
+
+        val request = Request.Builder()
+            .url("wss://$server")
+            .build()
+
+        client.newWebSocket(request, object : WebSocketListener() {
+            override fun onOpen(webSocket: WebSocket, response: Response) {
+                this@WebSocketClient.webSocket = webSocket
+                sendMessage("{\"token\":\"$token\",\"currentGroup\":\"$currentGroup\"}")
+                keepAlive()
+            }
+
+            @RequiresApi(Build.VERSION_CODES.O)
+            override fun onMessage(webSocket: WebSocket, text: String) {
+                val payload = JSONObject(text)
+
+                val item = payload["item"] as String
+                val data = payload["data"] as JSONObject
+                val action = payload["action"] as String
+                val currentGroup = payload["groupId"] as String
+
+                val dbHelper = DBStorageController(context, currentGroup)
+                val abstractProductDAO = AbstractProductDAO(dbHelper)
+                val productDAO = ProductDAO(dbHelper)
+                val categoryDAO = CategoryDAO(dbHelper)
+
+                when (action) {
+                    "create" -> {
+                        when (item) {
+                            "abstractproduct" -> {
+                                val newAbstractProduct = AbstractProduct.createFromJSON(data)
+
+                                val net = Net()
+                                net.server = server
+                                net.token = token
+
+                                val picturesDir = File(context.filesDir, "pictures")
+                                picturesDir.mkdirs()
+
+                                val pictureFile =
+                                    File(picturesDir, "${data["image_filename"]}.png")
+                                val url = "https://${net.server}/api/abstractproduct/getImage/${currentGroup}/${data["local_id"]}"
+                                net.downloadImage(url, pictureFile, {
+                                    abstractProductDAO.addAbstractProduct(newAbstractProduct)
+                                    (context as MainActivity).updateAll()
+                                })
+                            }
+
+                            "product" -> {
+                                val newProduct = Product.createFromJSON(data)
+                                productDAO.insertNewProduct(newProduct)
+                                (context as MainActivity).updateAll()
+                            }
+
+                            "category" -> {
+                                val newCategory = Category.createFromJSON(data)
+                                categoryDAO.addCategory(newCategory)
+                                (context as MainActivity).updateAll()
+                            }
+                        }
+                    }
+
+                    "update" -> {
+                        when (item) {
+                            "abstractproduct" -> {
+                                val updatedAbstractProduct = AbstractProduct.createFromJSON(data)
+
+                                val net = Net()
+                                net.server = server
+                                net.token = token
+
+                                val picturesDir = File(context.filesDir, "pictures")
+                                picturesDir.mkdirs()
+
+                                val pictureFile =
+                                    File(picturesDir, "${data["image_filename"]}.png")
+                                val url = "https://${net.server}/api/abstractproduct/getImage/${currentGroup}/${data["local_id"]}"
+                                net.downloadImage(url, pictureFile, {
+                                    abstractProductDAO.updateAbstractProduct(updatedAbstractProduct)
+                                    (context as MainActivity).updateAll()
+                                })
+
+                            }
+                            "product" -> {
+                                val updatedProduct = Product.createFromJSON(data)
+                                productDAO.updateProduct(updatedProduct)
+                                (context as MainActivity).updateAll()
+                            }
+                            "category" -> {
+                                val updatedCategory = Category.createFromJSON(data)
+                                categoryDAO.updateCategory(updatedCategory)
+                                (context as MainActivity).updateAll()
+                            }
+                        }
+                    }
+
+                    "delete" -> {
+                        val id = data["local_id"] as String
+
+                        when(item) {
+                            "abstractproduct" -> {
+                                abstractProductDAO.eraseAbstractProduct(id.toInt(), context)
+                                (context as MainActivity).updateAll()
+                            }
+                            "product" -> {
+                                productDAO.eraseProduct(id.toInt())
+                                (context as MainActivity).updateAll()
+                            }
+                            "category" -> {
+                                categoryDAO.eraseCategory(id.toInt(), context)
+                                (context as MainActivity).updateAll()
+                            }
+                        }
+                    }
+                }
+            }
+
+            override fun onClosing(webSocket: WebSocket, code: Int, reason: String) {
+                Log.d("QWERTYUIOP", "Closing ws. Reason: $reason")
+//                noInternetConnectionAvailableNotification(context)
+                this@WebSocketClient.connect(token, currentGroup)
+            }
+
+            override fun onFailure(webSocket: WebSocket, t: Throwable, response: Response?) {
+                Log.d("QWERTYUIOP","Connection failed: ${t.message}")
+                noInternetConnectionAvailableNotification(context)
+            }
+        })
+    }
+
+    private fun keepAlive() {
+        Thread {
+            while (true) {
+                Thread.sleep(30000)
+                webSocket.send("keepalive")
+            }
+        }.start()
+    }
+
+    fun sendMessage(message: String) {
+        webSocket.send(message)
+    }
+
+    fun close() {
+        webSocket.close(1000, "Closing WebSocket connection")
+    }
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/activities/AccountSettingsActivity.kt

@@ -0,0 +1,66 @@
+package org.foxarmy.barcodescannerforemployees.activities
+
+import android.content.Intent
+import android.os.Bundle
+import android.widget.Toast
+import androidx.appcompat.app.AppCompatActivity
+import org.foxarmy.barcodescannerforemployees.Net
+import org.foxarmy.barcodescannerforemployees.R
+import org.foxarmy.barcodescannerforemployees.databinding.ActivityAccountSettingsBinding
+
+class AccountSettingsActivity : AppCompatActivity() {
+
+    private lateinit var binding: ActivityAccountSettingsBinding
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        binding = ActivityAccountSettingsBinding.inflate(layoutInflater)
+
+        setContentView(binding.root)
+
+        val sharedPreferences = org.foxarmy.barcodescannerforemployees.getPreferences(this)
+
+        val net = Net()
+
+        net.server = sharedPreferences.getString("server", "bsfe.foxarmy.org")!!
+        net.language = sharedPreferences.getString("language", "")!!
+        net.token = sharedPreferences.getString("token", "")!!
+
+        binding.saveUsernameButton.setOnClickListener {
+            net.changeUsername(binding.newUsernameTextEdit.text.toString(), { response ->
+                if (response.code == 200) {
+                    runOnUiThread {
+                        Toast.makeText(this, getString(R.string.username_changed), Toast.LENGTH_LONG).show()
+                        val intent = Intent(this, LoginActivity::class.java)
+                        startActivity(intent)
+                        finish()
+                    }
+                } else {
+                    runOnUiThread {
+                        Toast.makeText(this, response.body!!.string(), Toast.LENGTH_LONG).show()
+                    }
+                }
+            })
+
+        }
+
+        binding.savePasswordButton.setOnClickListener {
+            net.changePassword(binding.newPasswordTextEdit.text.toString(), { response ->
+                if (response.code == 200) {
+                    runOnUiThread {
+                        Toast.makeText(this, getString(R.string.password_changed), Toast.LENGTH_LONG).show()
+                        val intent = Intent(this, LoginActivity::class.java)
+                        startActivity(intent)
+                        finish()
+                    }
+                } else {
+                    runOnUiThread {
+                        Toast.makeText(this, response.body!!.string(), Toast.LENGTH_LONG).show()
+                    }
+                }
+            })
+
+        }
+    }
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/activities/AddAbstractProductActivity.kt

@@ -1,11 +1,15 @@
 package org.foxarmy.barcodescannerforemployees.activities
 
-import android.content.ContentValues
+import android.app.ProgressDialog
 import android.content.DialogInterface
 import android.content.Intent
+import android.content.SharedPreferences
+import android.graphics.Bitmap
+import android.graphics.BitmapFactory
+import android.graphics.Matrix
+import android.media.ExifInterface
 import android.os.Build
 import android.os.Bundle
-import android.provider.BaseColumns
 import android.util.Log
 import android.widget.*
 import androidx.activity.result.contract.ActivityResultContracts
@@ -17,12 +21,16 @@ import androidx.core.widget.addTextChangedListener
 import com.journeyapps.barcodescanner.ScanContract
 import com.journeyapps.barcodescanner.ScanIntentResult
 import com.journeyapps.barcodescanner.ScanOptions
+import okhttp3.Response
 import org.foxarmy.barcodescannerforemployees.*
+import org.foxarmy.barcodescannerforemployees.database.AbstractProductDAO
+import org.foxarmy.barcodescannerforemployees.database.CategoryDAO
+import org.foxarmy.barcodescannerforemployees.database.DBStorageController
 import org.foxarmy.barcodescannerforemployees.dataclasses.AbstractProduct
 import java.io.File
+import java.io.FileOutputStream
 import java.nio.file.Files
 import java.nio.file.StandardCopyOption
-import kotlin.concurrent.thread
 
 class AddAbstractProductActivity : AppCompatActivity() {
     private lateinit var imageView: ImageView
@@ -47,11 +55,25 @@ class AddAbstractProductActivity : AppCompatActivity() {
 
     private var scanningBarcode = false
 
+    private lateinit var DAO: AbstractProductDAO
+    private lateinit var sharedPreferences: SharedPreferences
+
+    private lateinit var loadingDialog: ProgressDialog
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
         setContentView(R.layout.fragment_add_abstract_product)
 
+        loadingDialog = ProgressDialog(this)
+        loadingDialog.setMessage(getString(R.string.loading_please_wait))
+        loadingDialog.setCancelable(false)
+        loadingDialog.setTitle(getString(R.string.loading))
+
+        sharedPreferences = getPreferences(this)
+
+        val dbHelper = DBStorageController(this, sharedPreferences.getString("currentGroup", "offline")!!)
+        DAO = AbstractProductDAO(dbHelper)
 
         picturesPath = File(filesDir, "pictures")
         val thumbnailsDir = File(cacheDir, "thumbnails")
@@ -75,9 +97,7 @@ class AddAbstractProductActivity : AppCompatActivity() {
         fillupUnitsSpinner()
 
         noBarcodeCheckBox.setOnClickListener {
-            if (noBarcodeCheckBox.isChecked) {
-                barcodeText.setText("")
-            }
+            barcodeText.isEnabled = !noBarcodeCheckBox.isChecked
         }
 
         barcodeText.addTextChangedListener {
@@ -88,24 +108,28 @@ class AddAbstractProductActivity : AppCompatActivity() {
         action = extras!!.get("action") as String
         when (action) {
             "update" -> {
-                abstractProduct = extras.get("abstractProduct") as AbstractProduct?
+                abstractProduct = extras.get("abstractProduct") as AbstractProduct
             }
+
             "new_from_barcode" -> {
-                abstractProduct = extras.get("abstractProduct") as AbstractProduct?
+                abstractProduct = extras.get("abstractProduct") as AbstractProduct
                 barcode = abstractProduct!!.barcode
                 performRequest(abstractProduct!!.barcode)
             }
         }
 
-        if (abstractProduct != null) {
+        if (abstractProduct != null && action == "update") {
             val imageThumbnailUri = getImageUri(this, File(thumbnailsDir, "${abstractProduct!!.imageHash}.webp"))
-            pictureFile = File(picturesPath, "${abstractProduct!!.imageHash}.png]")
+            pictureFile = File(picturesPath, "${abstractProduct!!.imageHash}.png")
             imageView.setImageURI(imageThumbnailUri)
             barcodeText.setText(abstractProduct!!.barcode)
             productNameText.text = abstractProduct!!.name
             netWeightText.text = abstractProduct!!.netWeight.toString()
-            categorySpinner.setSelection(abstractProduct!!.category)
+            categorySpinner.setSelection(abstractProduct!!.category - 1)
             unitTypeSpinner.setSelection(abstractProduct!!.unit)
+            if (abstractProduct!!.barcode == "" || abstractProduct!!.barcode == "             ") {
+                noBarcodeCheckBox.isChecked = true
+            }
         }
 
         saveButton.setOnClickListener {
@@ -127,30 +151,47 @@ class AddAbstractProductActivity : AppCompatActivity() {
             }
             if (netWeight.toString() == "" || netWeight.toString().toDoubleOrNull() == null) {
                 Toast.makeText(this, getString(R.string.product_net_weight_request), Toast.LENGTH_SHORT).show()
+                return@setOnClickListener
             }
 
-            val db = DBStorageController(this).writableDatabase
-            val values = ContentValues().apply {
-                put(AbstractProductContract.AbstractProductEntry.BARCODE, barcode)
-                put(AbstractProductContract.AbstractProductEntry.PRODUCT_NAME, productName)
-                put(AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT, netWeight.toString())
-                put(AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME, pictureFile.nameWithoutExtension)
-                put(AbstractProductContract.AbstractProductEntry.CATEGORY, categorySpinner.selectedItemPosition)
-                put(AbstractProductContract.AbstractProductEntry.UNIT, unitTypeSpinner.selectedItemPosition)
+            loadingDialog.show()
+
+            val currentGroup: Int
+            val currentGroupString = sharedPreferences.getString("currentGroup", "offline")!!
+
+            val net = Net()
+
+            if (currentGroupString != "offline") {
+                currentGroup = currentGroupString.toInt()
+
+                net.token = sharedPreferences.getString("token", "")!!
+                net.server = sharedPreferences.getString("server", "")!!
+                net.language = sharedPreferences.getString("language", "en-US")!!
+
+            } else {
+                currentGroup = 0
             }
 
+            abstractProduct = AbstractProduct(
+                if (abstractProduct == null) 0 else abstractProduct!!.id,
+                if (noBarcodeCheckBox.isChecked) "" else barcode,
+                productName,
+                netWeight.toString().toDouble(),
+                pictureFile.nameWithoutExtension,
+                categorySpinner.selectedItemPosition + 1,
+                unitTypeSpinner.selectedItemPosition
+            )
+
+            val pictureFile = File(File(filesDir, "pictures"), "${abstractProduct!!.imageHash}.png")
+
             if (action == "update") {
-                db.update(
-                    AbstractProductContract.AbstractProductEntry.TABLE_NAME,
-                    values,
-                    "${BaseColumns._ID} = ?",
-                    arrayOf(abstractProduct!!.id.toString())
-                )
-            } else if (action == "new" || action == "new_from_barcode"){
-                db.insert(AbstractProductContract.AbstractProductEntry.TABLE_NAME, null, values)
+                DAO.updateAbstractProduct(abstractProduct!!)
+                if (currentGroup > 0) net.updateAbstractProduct(currentGroup, abstractProduct!!, pictureFile, this::notifyUserAndExit)
+            } else if (action == "new" || action == "new_from_barcode") {
+                abstractProduct!!.id = DAO.addAbstractProduct(abstractProduct!!).toInt()
+                if (currentGroup > 0)
+                    net.uploadAbstractProduct(currentGroup, abstractProduct!!, pictureFile, this::notifyUserAndExit)
             }
-
-            finish()
         }
 
         takePictureButton.setOnClickListener {
@@ -163,17 +204,20 @@ class AddAbstractProductActivity : AppCompatActivity() {
         }
     }
 
+    fun notifyUserAndExit(response: Response) {
+        runOnUiThread {
+            Toast.makeText(this, response.body!!.string(), Toast.LENGTH_LONG).show()
+            loadingDialog.dismiss()
+            finish()
+        }
+    }
+
     fun performRequest(barcode: String) {
         barcodeText.setText(this.barcode)
-        val requester = Requester("https://ean-online.ru", "match.php")
-        requester.request(this, barcode)
+
         var abstractProduct: AbstractProduct
 
-        if (DBStorageController(this).findAbstractProductByBarcode(
-                DBStorageController(this).readableDatabase,
-                this.barcode
-            ) != null
-        ) {
+        if (DAO.findAbstractProductByBarcode(this.barcode) != null) {
             AlertDialog.Builder(this)
                 .setMessage(getString(R.string.abstract_product_already_exists))
                 .setPositiveButton(getString(R.string.quit)) { _: DialogInterface, _: Int ->
@@ -182,10 +226,8 @@ class AddAbstractProductActivity : AppCompatActivity() {
                 .setNegativeButton(getString(R.string.edit_existing)) { _: DialogInterface, _: Int ->
                     val addProductIntent = Intent(this, AddAbstractProductActivity::class.java)
                     val extras = Bundle()
-                    val existingAbstractProduct = DBStorageController(this).findAbstractProductByBarcode(
-                        DBStorageController(this).readableDatabase,
-                        this.barcode
-                    )
+                    val existingAbstractProduct = DAO.findAbstractProductByBarcode(this.barcode)
+
                     extras.putParcelable("abstractProduct", existingAbstractProduct)
                     addProductIntent.putExtras(extras)
                     ContextCompat.startActivity(this, addProductIntent, extras)
@@ -193,26 +235,25 @@ class AddAbstractProductActivity : AppCompatActivity() {
                 }.show()
         }
 
-        thread {
-            // Я сам в ахуях какой это костыль, пока хз как фиксить, потом придумаю :))
-            while (requester.response == "") {
-            }
-            if (requester.response == "Not found 404") {
+        val net = Net();
+        net.requestProductFromOnlineDB(barcode, {response ->
+            if (response.code == 404) {
                 runOnUiThread {
                     Toast.makeText(this, getString(R.string.no_product_in_online_database), Toast.LENGTH_LONG)
                         .show()
+                    productNameText.setText("")
+                    netWeightText.setText("")
                 }
-                return@thread
+                return@requestProductFromOnlineDB
             }
 
-            abstractProduct = Parser().parse(requester.response)
-            requester.response = ""
+            abstractProduct = Parser().parse(response.body!!.string())
             runOnUiThread {
                 productNameText.text = abstractProduct.name
                 netWeightText.text = abstractProduct.netWeight.toString()
                 unitTypeSpinner.setSelection(abstractProduct.unit)
             }
-        }
+        })
     }
 
     private fun fillupUnitsSpinner() {
@@ -224,40 +265,21 @@ class AddAbstractProductActivity : AppCompatActivity() {
             getString(R.string.pieces)
         )
 
-
         val arrayAdapter =
-            ArrayAdapter<String>(this, androidx.appcompat.R.layout.support_simple_spinner_dropdown_item, units)
+            ArrayAdapter(this, androidx.appcompat.R.layout.support_simple_spinner_dropdown_item, units)
         arrayAdapter.setDropDownViewResource(androidx.appcompat.R.layout.support_simple_spinner_dropdown_item)
         unitTypeSpinner.adapter = arrayAdapter
     }
 
     fun fillupCategorySpinner() {
-        val db = DBStorageController(this).readableDatabase
 
-        val categories = mutableListOf("")
+        val categoriesDAO =
+            CategoryDAO(DBStorageController(this, sharedPreferences.getString("currentGroup", "database")!!))
 
-        val projection = arrayOf(
-            CategoriesContract.CategoryEntry.CATEGORY_NAME
-        )
-
-        val cursor = db.query(
-            CategoriesContract.CategoryEntry.TABLE_NAME,
-            projection,
-            null,
-            null,
-            null,
-            null,
-            BaseColumns._ID + " ASC"
-        )
-
-        with(cursor) {
-            while (moveToNext()) {
-                categories.add(getString(getColumnIndexOrThrow(CategoriesContract.CategoryEntry.CATEGORY_NAME)))
-            }
-        }
+        val categories = categoriesDAO.getAllCategories().map { category -> category.name }
 
         val arrayAdapter =
-            ArrayAdapter<String>(this, androidx.appcompat.R.layout.support_simple_spinner_dropdown_item, categories)
+            ArrayAdapter(this, androidx.appcompat.R.layout.support_simple_spinner_dropdown_item, categories)
         arrayAdapter.setDropDownViewResource(androidx.appcompat.R.layout.support_simple_spinner_dropdown_item)
         categorySpinner.adapter = arrayAdapter
     }
@@ -267,12 +289,34 @@ class AddAbstractProductActivity : AppCompatActivity() {
         if (success) {
             //Move picture to a proper directory according to its calculated hash
             val tempfile = File(filesDir, "image.png")
+
             val imageContent = tempfile.inputStream().readBytes()
-            val imageHash = imageContent.toString(Charsets.UTF_8).md5()
+            var img = BitmapFactory.decodeByteArray(imageContent, 0, imageContent.size)
+
+            val exif = ExifInterface(tempfile.absoluteFile.toString())
+            val orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL)
+            val matrix = Matrix()
+
+            when (orientation) {
+                ExifInterface.ORIENTATION_ROTATE_90 -> matrix.postRotate(90F)
+                ExifInterface.ORIENTATION_ROTATE_180 -> matrix.postRotate(180F)
+                ExifInterface.ORIENTATION_ROTATE_270 -> matrix.postRotate(270F)
+            }
+            val rotated = Bitmap.createBitmap(img, 0, 0, img.width, img.height, matrix, true)
+
+            val compressionFactor = sharedPreferences.getInt("compression", 1)
+            rotated.compress(
+                Bitmap.CompressFormat.WEBP_LOSSY,
+                100 * (15 / (16 - compressionFactor)),
+                FileOutputStream(tempfile)
+            )
+
+            val imageHash = calculateMd5Hash(tempfile)
 
             pictureFile = File(picturesPath, "$imageHash.png")
             Files.move(tempfile.toPath(), pictureFile.toPath(), StandardCopyOption.REPLACE_EXISTING)
             tempfile.delete()
+
             generateThumbnailForImage(this, imageHash)
 
             imageView.setImageURI(getImageUri(this, pictureFile))
@@ -303,7 +347,8 @@ class AddAbstractProductActivity : AppCompatActivity() {
                     getPicture()
                 }
             } else {
-                Toast.makeText(this, getString(R.string.camera_permission_for_picture_request), Toast.LENGTH_LONG).show()
+                Toast.makeText(this, getString(R.string.camera_permission_for_picture_request), Toast.LENGTH_LONG)
+                    .show()
             }
         }
 

app/src/main/java/org/foxarmy/barcodescannerforemployees/activities/AddCategoryActivity.kt

@@ -1,23 +1,40 @@
 package org.foxarmy.barcodescannerforemployees.activities
 
 import android.app.Activity
-import android.content.ContentValues
+import android.app.ProgressDialog
+import android.content.SharedPreferences
 import android.os.Bundle
-import android.provider.BaseColumns
 import android.widget.Button
 import android.widget.EditText
 import android.widget.Toast
-import org.foxarmy.barcodescannerforemployees.CategoriesContract
-import org.foxarmy.barcodescannerforemployees.DBStorageController
+import okhttp3.Response
+import org.foxarmy.barcodescannerforemployees.Net
 import org.foxarmy.barcodescannerforemployees.R
+import org.foxarmy.barcodescannerforemployees.database.CategoryDAO
+import org.foxarmy.barcodescannerforemployees.database.DBStorageController
 import org.foxarmy.barcodescannerforemployees.dataclasses.Category
 
 class AddCategoryActivity : Activity() {
+
+    private lateinit var DAO: CategoryDAO
+    private lateinit var sharedPreferences: SharedPreferences
+    private lateinit var loadingDialog: ProgressDialog
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
         setContentView(R.layout.activity_add_category)
 
+        loadingDialog = ProgressDialog(this)
+        loadingDialog.setMessage(getString(R.string.loading_please_wait))
+        loadingDialog.setCancelable(false)
+        loadingDialog.setTitle(getString(R.string.loading))
+
+        sharedPreferences = org.foxarmy.barcodescannerforemployees.getPreferences(this)
+
+        val dbHelper = DBStorageController(this, sharedPreferences.getString("currentGroup", "offline")!!)
+        DAO = CategoryDAO(dbHelper)
+
         val extras = intent.extras
         val category = extras!!.get("category") as Category?
 
@@ -25,28 +42,41 @@ class AddCategoryActivity : Activity() {
 
         categoryNameTextEdit.setText(category!!.name)
 
-        findViewById<Button>(R.id.saveButton).setOnClickListener {
-            val db = DBStorageController(this).writableDatabase
+        val net = Net()
 
+        net.token = sharedPreferences.getString("token", "")!!
+        net.server = sharedPreferences.getString("server", "")!!
+        net.language = sharedPreferences.getString("language", "")!!
+
+        val currentGroup: Int = if (sharedPreferences.getString(
+                "currentGroup",
+                "offline"
+            )!! == "offline"
+        ) 0 else sharedPreferences.getString("currentGroup", "")!!.toInt()
+
+        findViewById<Button>(R.id.saveButton).setOnClickListener {
             if (categoryNameTextEdit.text.toString() == "") {
                 Toast.makeText(this, getString(R.string.category_name_required), Toast.LENGTH_SHORT).show()
                 return@setOnClickListener
             }
+            loadingDialog.show()
 
             if (category.id == 0) { // Inserting new category
-                val values = ContentValues().apply {
-                    put(CategoriesContract.CategoryEntry.CATEGORY_NAME, categoryNameTextEdit.text.toString())
-                }
-
-                db.insert(CategoriesContract.CategoryEntry.TABLE_NAME, null, values)
+                val newCategory = Category(0, categoryNameTextEdit.text.toString())
+                newCategory.id = DAO.addCategory(newCategory).toInt()
+                if (currentGroup > 0) net.uploadCategory(currentGroup, newCategory, this::notifyUserAndExit)
             } else { // Updating existing category
-                val values = ContentValues().apply {
-                    put(CategoriesContract.CategoryEntry.CATEGORY_NAME, categoryNameTextEdit.text.toString())
-                }
-                db.update(CategoriesContract.CategoryEntry.TABLE_NAME, values, "${BaseColumns._ID} = ?", arrayOf(category.id.toString()))
+                category.name = categoryNameTextEdit.text.toString()
+                DAO.updateCategory(category)
+                if (currentGroup > 0) net.updateCategory(currentGroup, category, this::notifyUserAndExit)
             }
-
-            finish()
         }
     }
+    fun notifyUserAndExit(response: Response) {
+        runOnUiThread {
+            Toast.makeText(this, response.body!!.string(), Toast.LENGTH_SHORT).show()
+        }
+        loadingDialog.dismiss()
+        finish()
+    }
 }

app/src/main/java/org/foxarmy/barcodescannerforemployees/activities/AddProductActivity.kt

@@ -1,7 +1,9 @@
 package org.foxarmy.barcodescannerforemployees.activities
 
 import android.app.Activity
+import android.app.ProgressDialog
 import android.content.Intent
+import android.content.SharedPreferences
 import android.os.Build
 import android.os.Bundle
 import android.view.View
@@ -15,8 +17,12 @@ import androidx.core.widget.addTextChangedListener
 import com.journeyapps.barcodescanner.ScanContract
 import com.journeyapps.barcodescanner.ScanIntentResult
 import com.journeyapps.barcodescanner.ScanOptions
-import org.foxarmy.barcodescannerforemployees.DBStorageController
+import okhttp3.Response
+import org.foxarmy.barcodescannerforemployees.Net
 import org.foxarmy.barcodescannerforemployees.R
+import org.foxarmy.barcodescannerforemployees.database.AbstractProductDAO
+import org.foxarmy.barcodescannerforemployees.database.DBStorageController
+import org.foxarmy.barcodescannerforemployees.database.ProductDAO
 import org.foxarmy.barcodescannerforemployees.dataclasses.AbstractProduct
 import org.foxarmy.barcodescannerforemployees.dataclasses.Product
 import org.foxarmy.barcodescannerforemployees.views.AbstractProductView
@@ -45,11 +51,29 @@ class AddProductActivity : AppCompatActivity() {
     private var product: Product? = null
     private var abstractProduct: AbstractProduct? = null
 
+    private lateinit var productDAO: ProductDAO
+    private lateinit var abstractProductDAO: AbstractProductDAO
+    private lateinit var sharedPreferences: SharedPreferences
+
+    private lateinit var loadingDialog: ProgressDialog
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
         setContentView(R.layout.fragment_add_product)
 
+        loadingDialog = ProgressDialog(this)
+        loadingDialog.setMessage(getString(R.string.loading_please_wait))
+        loadingDialog.setCancelable(false)
+        loadingDialog.setTitle(getString(R.string.loading))
+
+        sharedPreferences = org.foxarmy.barcodescannerforemployees.getPreferences(this)
+
+        val dbHelper = DBStorageController(this, sharedPreferences.getString("currentGroup", "offline")!!)
+        productDAO = ProductDAO(dbHelper)
+        abstractProductDAO = AbstractProductDAO(dbHelper)
+
+
         scanButton = findViewById(R.id.scanButton)
         noBarcodeButton = findViewById(R.id.noBarcodeButton)
         abstractProductView = findViewById(R.id.abstractProductView)
@@ -70,7 +94,7 @@ class AddProductActivity : AppCompatActivity() {
         product = extras!!.get("product") as Product?
 
         if (product != null) {
-            abstractProduct = DBStorageController(this).findAbstractProductById(DBStorageController(this).readableDatabase, product!!.abstractProductId)
+            abstractProduct = abstractProductDAO.findAbstractProductById(product!!.abstractProductId)
             abstractProductView.abstractProduct = abstractProduct!!
             expiryDateRadioButton.isSelected = true
             shelfLifeRadioButton.isSelected = false
@@ -116,6 +140,12 @@ class AddProductActivity : AppCompatActivity() {
             product!!.amount = text.toInt()
         }
 
+        val net = Net()
+
+        net.language = sharedPreferences.getString("language", "en-US")!!
+        net.server = sharedPreferences.getString("server", "")!!
+        net.token = sharedPreferences.getString("token", "")!!
+
         saveProductButton.setOnClickListener {
             if (abstractProduct == null) {
                 Toast.makeText(this, getString(R.string.abstract_product_request), Toast.LENGTH_SHORT).show()
@@ -147,21 +177,36 @@ class AddProductActivity : AppCompatActivity() {
                 return@setOnClickListener
             }
 
-            if (updatingExistentProduct) {
-                DBStorageController(this).updateProduct(DBStorageController(this).writableDatabase, product!!)
-            } else {
-                DBStorageController(this).insertNewProduct(DBStorageController(this).writableDatabase, product!!)
-            }
+            loadingDialog.show()
 
-            finish()
+            val currentGroup: Int = if (sharedPreferences.getString("currentGroup", "offline")!! == "offline") 0 else sharedPreferences.getString("currentGroup", "")!!.toInt()
+
+            if (updatingExistentProduct) {
+                productDAO.updateProduct(product!!)
+                if (currentGroup > 0) net.updateProduct(currentGroup, product!!, this::notifyUserAndExit)
+            } else {
+                product!!.id = productDAO.insertNewProduct(product!!).toInt()
+                if (currentGroup > 0) net.uploadProduct(currentGroup, product!!, this::notifyUserAndExit)
+            }
         }
         update()
 
         val today = SimpleDateFormat("dd.MM.yyyy").format(Calendar.getInstance().time).split(".")
 
 
-        dateOfProductionDatePicker.updateDate(today[2].toInt(), today[1].toInt(), today[0].toInt())
-        expiryDatePicker.updateDate(today[2].toInt(), today[1].toInt(), today[0].toInt())
+        dateOfProductionDatePicker.updateDate(today[2].toInt(), today[1].toInt() - 1, today[0].toInt())
+        expiryDatePicker.updateDate(today[2].toInt(), today[1].toInt() - 1, today[0].toInt())
+        product!!.dateOfProduction = SimpleDateFormat("dd.MM.yyyy").parse("${today[0]}.${today[1]}.${today[2]}")!!.time / 1000
+
+
+    }
+
+    fun notifyUserAndExit(response: Response) {
+        runOnUiThread {
+            Toast.makeText(this, response.body!!.string(), Toast.LENGTH_LONG).show()
+            loadingDialog.dismiss()
+            finish()
+        }
     }
 
     private val intentLauncher =
@@ -245,7 +290,7 @@ class AddProductActivity : AppCompatActivity() {
                 Toast.makeText(this, getString(R.string.cancelled), Toast.LENGTH_SHORT).show()
             } else {
                 val scannedBarcode = result.contents
-                abstractProduct = DBStorageController(this).findAbstractProductByBarcode(DBStorageController(this).readableDatabase, scannedBarcode)
+                abstractProduct = abstractProductDAO.findAbstractProductByBarcode(scannedBarcode)
 
                 displayAbstractProduct(abstractProduct, scannedBarcode)
                 if (abstractProduct != null) {

app/src/main/java/org/foxarmy/barcodescannerforemployees/activities/ExpiryCalendarActivity.kt

@@ -2,23 +2,33 @@ package org.foxarmy.barcodescannerforemployees.activities
 
 import android.content.Context
 import android.content.Intent
+import android.content.SharedPreferences
 import android.os.Bundle
 import android.widget.LinearLayout
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.content.ContextCompat
-import org.foxarmy.barcodescannerforemployees.DBStorageController
 import org.foxarmy.barcodescannerforemployees.R
+import org.foxarmy.barcodescannerforemployees.database.DBStorageController
+import org.foxarmy.barcodescannerforemployees.database.ProductDAO
 import org.foxarmy.barcodescannerforemployees.databinding.ActivityExpiryCalendarBinding
 import org.foxarmy.barcodescannerforemployees.views.ExpiryGroupView
 
 class ExpiryCalendarActivity : AppCompatActivity() {
     private lateinit var binding: ActivityExpiryCalendarBinding
 
+    private lateinit var productDAO: ProductDAO
+    private lateinit var sharedPreferences: SharedPreferences
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
         setContentView(R.layout.fragment_expiry_dates)
 
+        sharedPreferences = org.foxarmy.barcodescannerforemployees.getPreferences(this)
+
+        val dbHelper = DBStorageController(this, sharedPreferences.getString("currentGroup", "database")!!)
+        productDAO = ProductDAO(dbHelper)
+
         fillUp()
     }
 
@@ -31,7 +41,7 @@ class ExpiryCalendarActivity : AppCompatActivity() {
     }
 
     private fun fillUp() {
-        val dates = DBStorageController(this).findAllExpiryDates(DBStorageController(this).readableDatabase)
+        val dates = productDAO.findAllExpiryDates()
 
         val container = findViewById<LinearLayout>(R.id.datesLinearLayout)
 

app/src/main/java/org/foxarmy/barcodescannerforemployees/activities/FindBarcodelessAbstractProduct.kt

@@ -18,7 +18,7 @@ class FindBarcodelessAbstractProduct() : AppCompatActivity() {
         binding = ActivityFindBarcodelessAbstractProductBinding.inflate(layoutInflater)
 
         val ft = supportFragmentManager.beginTransaction()
-        val fragment = StorageFragment.newInstance("barcodeless", arrayOf(""))
+        val fragment = StorageFragment.newInstance("barcodeless", arrayOf("", "             ", " "))
         ft.replace(R.id.content, fragment)
         ft.commit()
 

app/src/main/java/org/foxarmy/barcodescannerforemployees/activities/FullscreenActivity.kt

@@ -15,10 +15,7 @@ import java.io.File
 
 class FullscreenActivity : Activity() {
 
-    private lateinit var binding: ActivityFullscreenBinding
     private lateinit var fullscreenImageView: ImageView
-    private lateinit var fullscreenContentControls: LinearLayout
-    private val hideHandler = Handler(Looper.myLooper()!!)
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)

app/src/main/java/org/foxarmy/barcodescannerforemployees/activities/GroupActivity.kt

@@ -0,0 +1,123 @@
+package org.foxarmy.barcodescannerforemployees.activities
+
+import android.app.ProgressDialog
+import android.content.Intent
+import android.os.Bundle
+import android.widget.Toast
+import androidx.appcompat.app.AppCompatActivity
+import org.foxarmy.barcodescannerforemployees.Net
+import org.foxarmy.barcodescannerforemployees.R
+import org.foxarmy.barcodescannerforemployees.databinding.ActivityGroupBinding
+import org.foxarmy.barcodescannerforemployees.noInternetConnectionAvailableNotification
+
+class GroupActivity : AppCompatActivity() {
+
+    private lateinit var binding: ActivityGroupBinding
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        binding = ActivityGroupBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+
+        val loadingDialog = ProgressDialog(this)
+        loadingDialog.setMessage(getString(R.string.loading_please_wait))
+        loadingDialog.setCancelable(false)
+        loadingDialog.setTitle(getString(R.string.loading))
+
+        val sharedPreferences = org.foxarmy.barcodescannerforemployees.getPreferences(this)
+
+        binding.createGroupButton.setOnClickListener {
+            val groupName = binding.groupNameTextEdit.text.toString()
+            val groupPassword = binding.groupPasswordTextEdit.text.toString()
+            val net = Net()
+            net.language = sharedPreferences.getString("language", "en-US")!!
+            net.server = sharedPreferences.getString("server", "")!!
+            net.token = sharedPreferences.getString("token", "")!!
+
+            net.serverIsAvailable(this, { isServerAvailable ->
+                if (!isServerAvailable) {
+                    noInternetConnectionAvailableNotification(this)
+                } else {
+                    runOnUiThread {
+                        loadingDialog.show()
+                    }
+                    net.createGroup(groupName, groupPassword, { response ->
+                        val responseText = response.body!!.string()
+
+                        if (response.code == 200) {
+                            val currentGroups = sharedPreferences.getStringSet("groups", mutableSetOf())
+                            currentGroups!!.add(responseText)
+                            sharedPreferences.edit().putStringSet("groups", currentGroups).apply()
+                            sharedPreferences.edit().putString("currentGroup", responseText).apply()
+                            runOnUiThread {
+                                val intent = Intent(this, MainActivity::class.java)
+                                startActivity(intent)
+                                loadingDialog.dismiss()
+                                finish()
+                            }
+                        } else {
+                            runOnUiThread {
+                                loadingDialog.dismiss()
+                                Toast.makeText(this, responseText, Toast.LENGTH_LONG).show()
+                            }
+                        }
+                    })
+                }
+            })
+        }
+
+        binding.joinGroupButton.setOnClickListener {
+            val groupName = binding.groupNameTextEdit.text.toString()
+            val groupPassword = binding.groupPasswordTextEdit.text.toString()
+
+            val net = Net()
+            net.language = sharedPreferences.getString("language", "en-US")!!
+            net.server = sharedPreferences.getString("server", "")!!
+            net.token = sharedPreferences.getString("token", "")!!
+
+            net.serverIsAvailable(this) { isServerAvailable ->
+                if (!isServerAvailable) {
+                    noInternetConnectionAvailableNotification(this)
+                } else {
+                    runOnUiThread {
+                        loadingDialog.show()
+                    }
+                    net.getGroupId(groupName, { requestGroupIdResponse ->
+                        var groupId: Int
+                        try {
+                            groupId = requestGroupIdResponse.toInt()
+                        } catch (e: Exception) {
+                            runOnUiThread {
+                                loadingDialog.dismiss()
+                                Toast.makeText(this, requestGroupIdResponse, Toast.LENGTH_SHORT).show()
+                            }
+                            return@getGroupId
+                        }
+                        net.joinGroup(groupId, groupPassword, { response ->
+                            val responseText = response.body!!.string()
+
+                            if (response.code == 200) {
+                                val currentGroups = sharedPreferences.getStringSet("groups", mutableSetOf())
+                                currentGroups!!.add(groupId.toString())
+                                sharedPreferences.edit().putStringSet("groups", currentGroups).apply()
+                                sharedPreferences.edit().putString("currentGroup", groupId.toString()).apply()
+                                runOnUiThread {
+                                    val intent = Intent(this, MainActivity::class.java)
+                                    startActivity(intent)
+                                    loadingDialog.dismiss()
+                                    finish()
+                                }
+                            } else {
+                                runOnUiThread {
+                                    loadingDialog.dismiss()
+                                    Toast.makeText(this, responseText, Toast.LENGTH_LONG).show()
+                                }
+                            }
+                        })
+                    })
+                }
+            }
+        }
+    }
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/activities/LoginActivity.kt

@@ -0,0 +1,155 @@
+package org.foxarmy.barcodescannerforemployees.activities
+
+import android.app.ProgressDialog
+import android.content.Intent
+import android.os.Bundle
+import android.widget.ArrayAdapter
+import android.widget.Toast
+import androidx.appcompat.app.AppCompatActivity
+import org.foxarmy.barcodescannerforemployees.Net
+import org.foxarmy.barcodescannerforemployees.R
+import org.foxarmy.barcodescannerforemployees.databinding.ActivityLoginBinding
+import org.foxarmy.barcodescannerforemployees.noInternetConnectionAvailableNotification
+import org.foxarmy.barcodescannerforemployees.parseIntArray
+import org.json.JSONObject
+
+class LoginActivity : AppCompatActivity() {
+
+    private lateinit var binding: ActivityLoginBinding;
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        binding = ActivityLoginBinding.inflate(layoutInflater);
+        setContentView(binding.root)
+
+        val loadingDialog = ProgressDialog(this)
+        loadingDialog.setMessage(getString(R.string.loading_please_wait))
+        loadingDialog.setCancelable(false)
+        loadingDialog.setTitle(getString(R.string.loading))
+
+        fillUpLanguagesSpinner()
+
+        val sharedPreferences = org.foxarmy.barcodescannerforemployees.getPreferences(this)
+
+        binding.loginButton.setOnClickListener {
+            val server = binding.serverTextEdit.text.toString()
+            val username = binding.usernameTextEdit.text.toString()
+            val password = binding.passwordTextEdit.text.toString()
+            val language = resources.getStringArray(R.array.languages)[binding.languageSpinner.selectedItemPosition]
+            sharedPreferences.edit().putString("language", language).apply()
+
+            val net = Net()
+            net.language = sharedPreferences.getString("language", "en-US")!!
+            net.server = server
+
+            net.serverIsAvailable(this, { isServerAvailable ->
+                if (!isServerAvailable) {
+                    noInternetConnectionAvailableNotification(this)
+                } else {
+                    runOnUiThread {
+                        loadingDialog.show()
+                    }
+                    net.login(username, password, { response ->
+                        val responseText = response.body!!.string()
+                        if (response.code != 200) {
+                            runOnUiThread {
+                                Toast.makeText(this, responseText, Toast.LENGTH_SHORT).show()
+                            }
+                        } else {
+                            val json = JSONObject(responseText)
+                            sharedPreferences.edit().putString("token", json["token"].toString()).apply()
+                            net.token = json["token"].toString()
+                            sharedPreferences.edit().putInt("userId", json["id"].toString().toInt()).apply()
+                            sharedPreferences.edit().putString("server", server).apply()
+
+                            net.getMyGroups({ response ->
+                                runOnUiThread {
+                                    loadingDialog.dismiss()
+                                }
+                                val r = response.body!!.string()
+                                if (r == "" || r == "[]") {
+                                    goToActivity("GroupActivity")
+                                }
+                                val myGroups = parseIntArray(r).map { a -> a.toString() }
+
+                                sharedPreferences.edit().putStringSet("groups", myGroups.toSet()).apply()
+                                sharedPreferences.edit().putString("currentGroup", myGroups[0]).apply()
+
+                                goToActivity("MainActivity")
+                            })
+                        }
+                    })
+                }
+            })
+        }
+
+        binding.registerButton.setOnClickListener {
+            val server = binding.serverTextEdit.text.toString()
+            val username = binding.usernameTextEdit.text.toString()
+            val password = binding.passwordTextEdit.text.toString()
+            val language = resources.getStringArray(R.array.languages)[binding.languageSpinner.selectedItemPosition]
+            sharedPreferences.edit().putString("language", language).apply()
+            sharedPreferences.edit().putString("server", server).apply()
+
+            val net = Net()
+            net.language = language
+            net.server = server
+
+            net.serverIsAvailable(this, {isServerAvailable ->
+                if (!isServerAvailable) {
+                    noInternetConnectionAvailableNotification(this)
+                } else {
+                    net.registerAccount(username, password, {response ->
+                        val responseText = response.body!!.string()
+                        if (response.code != 200) {
+                            Toast.makeText(this, responseText, Toast.LENGTH_SHORT).show();
+                        } else {
+                            sharedPreferences.edit().putInt("userId", responseText.toInt()).apply()
+                            net.login(username, password, {response ->
+                                val token = JSONObject(response.body!!.string())["token"].toString()
+                                sharedPreferences.edit().putString("token", token).apply()
+
+                                sharedPreferences.edit().putString("server", server).apply()
+                                runOnUiThread {
+                                    loadingDialog.dismiss()
+                                }
+                                goToActivity("GroupActivity")
+                            })
+                        }
+                    })
+                }
+            })
+        }
+
+        binding.offlineButton.setOnClickListener {
+            sharedPreferences.edit().putString("currentGroup", "offline").apply()
+            sharedPreferences.edit().putStringSet("groups", setOf("offline")).apply()
+
+            val intent = Intent(this, MainActivity::class.java)
+            startActivity(intent)
+            finish()
+        }
+    }
+
+    private fun fillUpLanguagesSpinner() {
+        val languages = resources.getStringArray(R.array.languages)
+        val arrayAdapter =
+            ArrayAdapter(this, androidx.appcompat.R.layout.support_simple_spinner_dropdown_item, languages)
+        arrayAdapter.setDropDownViewResource(androidx.appcompat.R.layout.support_simple_spinner_dropdown_item)
+        binding.languageSpinner.adapter = arrayAdapter
+    }
+
+    private fun goToActivity(activityName: String) {
+        runOnUiThread {
+            val intent = Intent(this, when(activityName) {
+                "MainActivity" -> MainActivity::class.java
+                "GroupActivity" -> GroupActivity::class.java
+                "LoginActivity" -> LoginActivity::class.java
+                else -> LoginActivity::class.java
+            })
+            startActivity(intent)
+            finish()
+        }
+    }
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/activities/MainActivity.kt

@@ -1,26 +1,54 @@
 package org.foxarmy.barcodescannerforemployees.activities
 
+import android.app.Activity
+import android.app.ProgressDialog
 import android.content.DialogInterface
 import android.content.Intent
+import android.content.SharedPreferences
 import android.os.Bundle
+import android.util.Log
 import android.view.Menu
 import android.view.MenuItem
+import android.widget.Toast
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.appcompat.app.ActionBarDrawerToggle
 import androidx.appcompat.app.AlertDialog
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.content.ContextCompat
+import androidx.drawerlayout.widget.DrawerLayout
 import androidx.viewpager.widget.ViewPager
-import org.foxarmy.barcodescannerforemployees.R
-import org.foxarmy.barcodescannerforemployees.ViewPagerAdapter
+import com.google.android.material.navigation.NavigationView
+import org.foxarmy.barcodescannerforemployees.*
+import org.foxarmy.barcodescannerforemployees.database.AbstractProductDAO
+import org.foxarmy.barcodescannerforemployees.database.CategoryDAO
+import org.foxarmy.barcodescannerforemployees.database.DBStorageController
+import org.foxarmy.barcodescannerforemployees.database.ProductDAO
 import org.foxarmy.barcodescannerforemployees.databinding.ActivityMainBinding
+import org.foxarmy.barcodescannerforemployees.dataclasses.AbstractProduct
 import org.foxarmy.barcodescannerforemployees.dataclasses.Category
+import org.foxarmy.barcodescannerforemployees.dataclasses.Product
 import org.foxarmy.barcodescannerforemployees.fragments.CategoriesFragment
 import org.foxarmy.barcodescannerforemployees.fragments.ShelfFragment
 import org.foxarmy.barcodescannerforemployees.fragments.StorageFragment
+import org.json.JSONArray
+import org.json.JSONObject
+import java.io.File
 
-class MainActivity : AppCompatActivity() {
+
+class MainActivity : AppCompatActivity(), NavigationView.OnNavigationItemSelectedListener {
 
     private lateinit var binding: ActivityMainBinding
-    lateinit var adapter: ViewPagerAdapter
+    private lateinit var adapter: ViewPagerAdapter
+    private var drawerLayout: DrawerLayout? = null
+    private var actionBarDrawerToggle: ActionBarDrawerToggle? = null
+    private lateinit var ws: WebSocketClient
+
+    var selectionMode = false
+    private var selectedAmount = 0
+
+    private lateinit var sharedPreferences: SharedPreferences
+
+    private lateinit var loadingDialog: ProgressDialog
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -28,10 +56,32 @@ class MainActivity : AppCompatActivity() {
         binding = ActivityMainBinding.inflate(layoutInflater)
         setContentView(binding.root)
 
+        loadingDialog = ProgressDialog(this)
+        loadingDialog.setMessage(getString(R.string.loading_please_wait))
+        loadingDialog.setCancelable(false)
+        loadingDialog.setTitle(getString(R.string.loading))
+
+        sharedPreferences = getPreferences(this)
+
         setSupportActionBar(binding.toolbar)
         setupViewPager(binding.tabViewpager)
         binding.tabTablayout.setupWithViewPager(binding.tabViewpager)
 
+        binding.tabTablayout.setOnDragListener { _, _ ->
+            selectionMode = false
+            selectedAmount = 0
+            true
+        }
+
+        drawerLayout = binding.drawerLayout
+        actionBarDrawerToggle = ActionBarDrawerToggle(this, drawerLayout, R.string.nav_open, R.string.nav_close)
+
+        drawerLayout!!.addDrawerListener(actionBarDrawerToggle!!)
+        actionBarDrawerToggle!!.syncState()
+        binding.navView.setNavigationItemSelectedListener(this)
+
+        supportActionBar!!.setDisplayHomeAsUpEnabled(true)
+
         binding.expiryCalendarFab.setOnClickListener { _ ->
             val expiryCalendarIntent = Intent(this, ExpiryCalendarActivity::class.java)
             val extras = Bundle()
@@ -39,7 +89,7 @@ class MainActivity : AppCompatActivity() {
             ContextCompat.startActivity(this, expiryCalendarIntent, extras)
         }
 
-        binding.newElementFab.setOnClickListener { view ->
+        binding.newElementFab.setOnClickListener { _ ->
             val currentPosition = binding.tabTablayout.selectedTabPosition
             val fragment = adapter.getItem(currentPosition)
 
@@ -47,8 +97,6 @@ class MainActivity : AppCompatActivity() {
                 "StorageFragment" -> {
                     val addAbstractProductIntent = Intent(this, AddAbstractProductActivity::class.java)
                     val extras = Bundle()
-                    // I reuse the same stuff for editing and adding new product.
-                    // if abstractProduct == null, it means that we need to create new object
                     extras.putParcelable("abstractProduct", null)
                     extras.putString("action", "new")
                     addAbstractProductIntent.putExtras(extras)
@@ -69,6 +117,220 @@ class MainActivity : AppCompatActivity() {
                     extras.putParcelable("product", null)
                     addProductIntent.putExtras(extras)
                     ContextCompat.startActivity(this, addProductIntent, extras)
+
+                }
+            }
+        }
+        val net = Net()
+        net.server = sharedPreferences.getString("server", "")!!
+        val currentGroup = sharedPreferences.getString("currentGroup", "offline")!!
+        net.serverIsAvailable(this, {isServerAvailable ->
+            if ( currentGroup != "offline" && !isServerAvailable) {
+                runOnUiThread {
+                    noInternetConnectionAvailableNotification(this)
+                }
+            } else if (currentGroup != "offline" && isServerAvailable) {
+                synchronize()
+                ws = WebSocketClient(this, sharedPreferences.getString("server", "")!!)
+                val token = sharedPreferences.getString("token", "")!!
+                ws.connect(token, currentGroup)
+            }
+        })
+    }
+
+    private fun synchronize() {
+        if (sharedPreferences.getString("currentGroup", "offline")!! == "offline") return
+
+        val net = Net()
+
+        net.language = sharedPreferences.getString("language", "en-US")!!
+        net.server = sharedPreferences.getString("server", "")!!
+        net.token = sharedPreferences.getString("token", "")!!
+
+        val currentGroup = sharedPreferences.getString("currentGroup", "")!!.toInt()
+
+        net.synchronize(currentGroup, {response ->
+            val data = JSONObject(response.body!!.string())
+
+            val remoteAbstractProducts = data["abstract_products"] as JSONArray
+            val remoteProducts = data["products"] as JSONArray
+            val remoteCategories = data["categories"] as JSONArray
+
+            val dbHelper = DBStorageController(this, sharedPreferences.getString("currentGroup", "")!!)
+
+            val abstractProductDAO = AbstractProductDAO(dbHelper)
+            val productDAO = ProductDAO(dbHelper)
+            val categoryDAO = CategoryDAO(dbHelper)
+
+            val localAbstractProducts = abstractProductDAO.getSortedListOfAbstractProducts(0, "", arrayOf(""))
+            val localProducts = productDAO.getSortedListOfProducts(0, "", "")
+            val localCategories = categoryDAO.getAllCategories()
+
+            syncAbstractProducts(net, currentGroup, abstractProductDAO, remoteAbstractProducts, localAbstractProducts)
+            syncProducts(productDAO, remoteProducts, localProducts)
+            syncCategories(categoryDAO, remoteCategories, localCategories)
+        })
+    }
+
+    private fun syncCategories(
+        categoryDAO: CategoryDAO,
+        remoteCategories: JSONArray,
+        localCategories: List<Category>
+    ) {
+        for (localCategory in localCategories) {
+            var found = false
+            for (i in 0 until remoteCategories.length()) {
+                val remoteProduct = remoteCategories.getJSONObject(i)
+                if (remoteProduct["local_id"] == localCategory.id) {
+                    found = true
+                    break
+                }
+            }
+            if (!found) categoryDAO.eraseCategory(localCategory.id, this)
+        }
+        for (i in 0 until remoteCategories.length()) {
+            var categoryInRemoteDB: JSONObject? = null
+            var categoryInLocalDB: Category? = null
+
+            val remoteCategory = remoteCategories.getJSONObject(i)
+
+            for (localCategory in localCategories) {
+                if (remoteCategory["local_id"] == localCategory.id) {
+                    categoryInRemoteDB = remoteCategory
+                    categoryInLocalDB = localCategory
+                    break
+                }
+            }
+
+            if (categoryInLocalDB == null && remoteCategory != null) {
+                var newCategory: Category
+
+                with(remoteCategory) {
+                    newCategory = Category(
+                        this["local_id"].toString().toInt(),
+                        this["name"].toString()
+                    )
+                }
+
+                categoryDAO.addCategory(newCategory)
+            }
+
+            if (categoryInRemoteDB != null && categoryInLocalDB != null) {
+                if (categoryInRemoteDB["hash"] != categoryInLocalDB.calculateHash()) {
+                    val updatedData = Category.createFromJSON(categoryInRemoteDB)
+
+                    categoryDAO.updateCategory(updatedData)
+                }
+            }
+        }
+    }
+
+    private fun syncProducts(
+        productDAO: ProductDAO,
+        remoteProducts: JSONArray,
+        localProducts: List<Product>
+    ) {
+        for (localProduct in localProducts) {
+            var found = false
+            for (i in 0 until remoteProducts.length()) {
+                val remoteProduct = remoteProducts.getJSONObject(i)
+                if (remoteProduct["local_id"] == localProduct.id) {
+                    found = true
+                    break
+                }
+            }
+            if (!found) productDAO.eraseProduct(localProduct.id)
+        }
+        for (i in 0 until remoteProducts.length()) {
+            var productInRemoteDB: JSONObject? = null
+            var productInLocalDB: Product? = null
+
+            val remoteProduct = remoteProducts.getJSONObject(i)
+
+            for (localProduct in localProducts) {
+                if (remoteProduct["local_id"] == localProduct.id) {
+                    productInRemoteDB = remoteProduct
+                    productInLocalDB = localProduct
+                    break
+                }
+            }
+
+            if (productInLocalDB == null && remoteProduct != null) {
+                val newProduct = Product.createFromJSON(remoteProduct)
+
+                productDAO.insertNewProduct(newProduct)
+            }
+
+            if (productInRemoteDB != null && productInLocalDB != null) {
+                if (productInRemoteDB["hash"] != productInLocalDB.calculateHash()) {
+                    val updatedData = Product.createFromJSON(productInRemoteDB)
+
+                    productDAO.updateProduct(updatedData)
+                }
+            }
+        }
+    }
+
+    private fun syncAbstractProducts(
+        net: Net,
+        currentGroup: Int,
+        abstractProductDAO: AbstractProductDAO,
+        remoteAbstractProducts: JSONArray,
+        localAbstractProducts: List<AbstractProduct>
+    ) {
+        for (localAbstractProduct in localAbstractProducts) {
+            var found = false
+            for (i in 0 until remoteAbstractProducts.length()) {
+                val remoteAbstractProduct = remoteAbstractProducts.getJSONObject(i)
+                if (remoteAbstractProduct["local_id"] == localAbstractProduct.id) {
+                    found = true
+                    break
+                }
+            }
+            if (!found) abstractProductDAO.eraseAbstractProduct(localAbstractProduct.id, this)
+        }
+        for (i in 0 until remoteAbstractProducts.length()) {
+            var abstractProductInRemoteDB: JSONObject? = null
+            var abstractProductInLocalDB: AbstractProduct? = null
+
+            val remoteAbstractProduct = remoteAbstractProducts.getJSONObject(i)
+
+            for (localAbstractProduct in localAbstractProducts) {
+                if (remoteAbstractProduct["local_id"] == localAbstractProduct.id) {
+                    abstractProductInRemoteDB = remoteAbstractProduct
+                    abstractProductInLocalDB = localAbstractProduct
+                    break
+                }
+            }
+
+            if (abstractProductInLocalDB == null && remoteAbstractProduct != null) {
+                val localId = remoteAbstractProduct["local_id"].toString().toInt()
+
+                val picturesDir = File(filesDir, "pictures")
+                picturesDir.mkdirs()
+
+                val pictureFile =
+                    File(picturesDir, "${remoteAbstractProduct["image_filename"]}.png")
+                val url = "https://${net.server}/api/abstractproduct/getImage/${currentGroup}/${localId}"
+                net.downloadImage(url, pictureFile, {
+                    val newAbstractProduct = AbstractProduct.createFromJSON(remoteAbstractProduct)
+
+                    abstractProductDAO.addAbstractProduct(newAbstractProduct)
+                })
+            }
+
+            if (abstractProductInRemoteDB != null && abstractProductInLocalDB != null) {
+                if (abstractProductInRemoteDB["hash"] != abstractProductInLocalDB.calculateHash()) {
+                    val localId = abstractProductInRemoteDB["local_id"].toString().toInt()
+
+                    val pictureFile =
+                        File(File(filesDir, "pictures"), "${abstractProductInRemoteDB["image_filename"]}.png")
+                    val url = "https://${net.server}/api/abstractproduct/getImage/${currentGroup}/${localId}"
+                    net.downloadImage(url, pictureFile, {
+                        val updatedData = AbstractProduct.createFromJSON(abstractProductInRemoteDB)
+
+                        abstractProductDAO.updateAbstractProduct(updatedData)
+                    })
                 }
             }
         }
@@ -81,84 +343,157 @@ class MainActivity : AppCompatActivity() {
         adapter.addFragment(ShelfFragment(), getString(R.string.shelf_title))
         adapter.addFragment(CategoriesFragment(), getString(R.string.categories_title))
 
-        //TODO: settings fragments
-
-        // setting adapter to view pager.
         viewpager.adapter = adapter
+        viewpager.offscreenPageLimit = 3
     }
 
     override fun onCreateOptionsMenu(menu: Menu): Boolean {
         menuInflater.inflate(R.menu.menu_main, menu)
+
         return true
     }
 
-    override fun onOptionsItemSelected(item: MenuItem): Boolean {
-        val currentPosition = binding.tabTablayout.selectedTabPosition
-        val fragment = adapter.getItem(currentPosition)
+    private fun isOffline(): Boolean {
+        return sharedPreferences.getString("currentGroup", "") == "offline"
+    }
 
-        return when (item.itemId) {
-
-
-            R.id.action_settings -> {
-                true
-            }
-
-            R.id.action_delete -> {
-
-                when (fragment::class.simpleName.toString()) {
-                    "StorageFragment" -> {
-                        AlertDialog.Builder(this)
-                            .setMessage(getString(R.string.deleting_abstract_product_warning))
-                            .setPositiveButton(getString(R.string.yes)) { _: DialogInterface, _: Int ->
-                                val storageFragment = fragment as StorageFragment
-                                storageFragment.removeSelected()
-                            }
-                            .setNegativeButton(getString(R.string.no)) { _: DialogInterface, _: Int ->
-
-                            }.show()
-                    }
-
-                    "CategoriesFragment" -> {
-                        AlertDialog.Builder(this)
-                            .setMessage(getString(R.string.deleting_category_warning))
-                            .setPositiveButton(getString(R.string.yes)) { _: DialogInterface, _: Int ->
-                                val categoriesFragment = fragment as CategoriesFragment
-                                categoriesFragment.removeSelected()
-                            }
-                            .setNegativeButton(getString(R.string.no)) { _: DialogInterface, _: Int ->
-
-                            }.show()
-                    }
-                    "ShelfFragment" -> {
-                        val shelfFragment = fragment as ShelfFragment
-                        shelfFragment.removeSelected()
-                    }
+    override fun onNavigationItemSelected(item: MenuItem): Boolean {
+        lateinit var intent: Intent
+        when (item.itemId) {
+            R.id.nav_account -> {
+                if (isOffline()) {
+                    Toast.makeText(this, getString(R.string.online_only_feature), Toast.LENGTH_SHORT).show()
+                    return false
                 }
-                true
+                intent = Intent(this, AccountSettingsActivity::class.java)
+                settingsActivityLauncher.launch(intent)
+                return true
             }
 
-            R.id.action_update -> {
-                when (fragment::class.simpleName.toString()) {
-                    "StorageFragment" -> {
-                        val storageFragment = fragment as StorageFragment
-                        storageFragment.updateSelected()
-                    }
-
-                    "CategoriesFragment" -> {
-                        val categoriesFragment = fragment as CategoriesFragment
-                        categoriesFragment.updateSelected()
-                    }
-
-                    "ShelfFragment" -> {
-                        val shelfFragment = fragment as ShelfFragment
-                        shelfFragment.updateSelected()
-                    }
+            R.id.nav_groups -> {
+                if (isOffline()) {
+                    Toast.makeText(this, getString(R.string.online_only_feature), Toast.LENGTH_SHORT).show()
+                    return false
                 }
-                true
+                intent = Intent(this, MyGroupsActivity::class.java)
             }
 
-            else -> super.onOptionsItemSelected(item)
+            R.id.nav_settings -> {
+                intent = Intent(this, SettingsActivity::class.java)
+            }
+
+            R.id.nav_logout -> {
+                sharedPreferences.edit().putString("currentGroup", "").apply()
+                sharedPreferences.edit().putStringSet("groups", emptySet()).apply()
+                sharedPreferences.edit().putString("token", "").apply()
+                sharedPreferences.edit().putString("server", "").apply()
+
+                intent = Intent(this, LoginActivity::class.java)
+            }
         }
+        startActivity(intent)
+
+        return true
+    }
+
+    private val settingsActivityLauncher = registerForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->
+        if (result.resultCode == Activity.RESULT_OK) {
+            synchronize()
+            updateAll()
+        }/* else if (result.resultCode == Activity.RESULT_CANCELED) {
+
+        }*/
+    }
+
+    fun updateAll() {
+        runOnUiThread {
+            try {
+                val storageFragment: StorageFragment = adapter.getItem(0) as StorageFragment
+                val shelfFragment: ShelfFragment = adapter.getItem(1) as ShelfFragment
+                val categoriesFragment: CategoriesFragment = adapter.getItem(2) as CategoriesFragment
+
+                storageFragment.updateContent()
+                shelfFragment.updateContent()
+                categoriesFragment.updateContent()
+            } catch (e:Exception) {
+                Log.e("BSFE/MainActivity", e.message!!)
+            }
+        }
+    }
+
+    override fun onOptionsItemSelected(item: MenuItem): Boolean {
+        if (actionBarDrawerToggle!!.onOptionsItemSelected(item)) {
+            return true
+        } else {
+
+            val currentPosition = binding.tabTablayout.selectedTabPosition
+            val fragment = adapter.getItem(currentPosition)
+
+            return when (item.itemId) {
+                R.id.action_settings -> {
+                    val intent = Intent(this, SettingsActivity::class.java)
+                    settingsActivityLauncher.launch(intent)
+                    true
+                }
+
+                R.id.action_delete -> {
+                    when (fragment::class.simpleName.toString()) {
+                        "StorageFragment" -> {
+                            AlertDialog.Builder(this)
+                                .setMessage(getString(R.string.deleting_abstract_product_warning))
+                                .setPositiveButton(getString(R.string.yes)) { _: DialogInterface, _: Int ->
+                                    val storageFragment = fragment as StorageFragment
+                                    storageFragment.removeSelected()
+                                }
+                                .setNegativeButton(getString(R.string.no)) { _: DialogInterface, _: Int ->
+
+                                }.show()
+                        }
+
+                        "CategoriesFragment" -> {
+                            AlertDialog.Builder(this)
+                                .setMessage(getString(R.string.deleting_category_warning))
+                                .setPositiveButton(getString(R.string.yes)) { _: DialogInterface, _: Int ->
+                                    val categoriesFragment = fragment as CategoriesFragment
+                                    categoriesFragment.removeSelected()
+                                }
+                                .setNegativeButton(getString(R.string.no)) { _: DialogInterface, _: Int ->
+
+                                }.show()
+                        }
+
+                        "ShelfFragment" -> {
+                            val shelfFragment = fragment as ShelfFragment
+                            shelfFragment.removeSelected()
+                        }
+                    }
+                    true
+                }
+
+                R.id.action_update -> {
+                    when (fragment::class.simpleName.toString()) {
+                        "StorageFragment" -> {
+                            val storageFragment = fragment as StorageFragment
+                            storageFragment.updateSelected()
+                        }
+
+                        "CategoriesFragment" -> {
+                            val categoriesFragment = fragment as CategoriesFragment
+                            categoriesFragment.updateSelected()
+                        }
+
+                        "ShelfFragment" -> {
+                            val shelfFragment = fragment as ShelfFragment
+                            shelfFragment.updateSelected()
+                        }
+                    }
+                    true
+                }
+
+                else -> super.onOptionsItemSelected(item)
+            }
+        }
+
     }
 
     fun filterAbstractProductsByCategory(id: Int) {
@@ -170,4 +505,17 @@ class MainActivity : AppCompatActivity() {
         val storageFragment = fragment as StorageFragment
         storageFragment.filterByCategory(id)
     }
+
+    fun addSelection() {
+        selectionMode = true
+        selectedAmount ++
+    }
+
+    fun removeSelection() {
+        selectedAmount --
+        if (selectedAmount <= 0) {
+            selectedAmount = 0
+            selectionMode = false
+        }
+    }
 }

app/src/main/java/org/foxarmy/barcodescannerforemployees/activities/ManageGroupActivity.kt

@@ -0,0 +1,178 @@
+package org.foxarmy.barcodescannerforemployees.activities
+
+import android.content.Context
+import android.content.Intent
+import android.content.SharedPreferences
+import android.os.Bundle
+import android.view.View
+import android.widget.EditText
+import android.widget.PopupMenu
+import android.widget.Toast
+import androidx.appcompat.app.AlertDialog
+import androidx.appcompat.app.AppCompatActivity
+import org.foxarmy.barcodescannerforemployees.Net
+import org.foxarmy.barcodescannerforemployees.R
+import org.foxarmy.barcodescannerforemployees.databinding.ActivityManageGroupBinding
+import org.foxarmy.barcodescannerforemployees.parseIntArray
+import org.foxarmy.barcodescannerforemployees.views.GroupMemberView
+
+class ManageGroupActivity : AppCompatActivity() {
+    private lateinit var binding: ActivityManageGroupBinding
+    private var isAdmin: Boolean = false
+    private lateinit var sharedPreferences: SharedPreferences
+    private lateinit var net: Net
+    private var groupId: Int = 0
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        binding = ActivityManageGroupBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+
+        groupId = intent.extras!!.getInt("groupId")
+
+        sharedPreferences = org.foxarmy.barcodescannerforemployees.getPreferences(this)
+
+        net = Net()
+
+        net.token = sharedPreferences.getString("token", "")!!
+        net.server = sharedPreferences.getString("server", "")!!
+        net.language = sharedPreferences.getString("language", "en-US")!!
+
+
+        setUpMembers()
+
+        binding.renameButton.setOnClickListener {
+            val input = EditText(this)
+            AlertDialog.Builder(this)
+                .setTitle(getString(R.string.new_group_name))
+                .setView(input)
+                .setPositiveButton(getString(R.string.ok)) { _, _ ->
+                    val newName = input.text.toString()
+                    net.renameGroup(groupId, newName, { response ->
+                        runOnUiThread {
+                            Toast.makeText(this, response.body!!.string(), Toast.LENGTH_LONG).show()
+                        }
+                    })
+
+                }
+                .setNegativeButton(getString(R.string.cancel)) { _, _ ->
+
+                }.show()
+        }
+
+        binding.leaveButton.setOnClickListener {
+            net.leaveGroup(groupId, { response ->
+                runOnUiThread {
+                    Toast.makeText(this, response.body!!.string(), Toast.LENGTH_SHORT).show()
+                }
+                if (response.code == 200) {
+                    val groups = sharedPreferences.getStringSet("groups", emptySet())!!
+                    groups.remove(groupId.toString())
+                    sharedPreferences.edit().putStringSet("groups", groups).apply()
+                    sharedPreferences.edit().putString("currentGroup", "").apply()
+
+                    if (groups.isEmpty()) {
+                        runOnUiThread {
+                            val intent = Intent(this, GroupActivity::class.java)
+                            startActivity(intent)
+                            finish()
+                        }
+                    }
+                    sharedPreferences.edit().putString("currentGroup", groups.toList()[0]).apply()
+                    runOnUiThread {
+                        finish()
+                    }
+                }
+            })
+        }
+
+        setUpAdminRelatedButtons()
+    }
+
+    private fun setUpMembers() {
+        net.getUsersInGroup(groupId, { response ->
+            val users = parseIntArray(response.body!!.string())
+            for (user in users) {
+                net.getUsernameById(user, { response ->
+                    val groupMemberView = GroupMemberView(this, this as Context, response.body!!.string(), user)
+
+                    groupMemberView.setOnLongClickListener { view ->
+                        amIAnAdminIn(groupId, { amIAnAdmin ->
+                            if (!amIAnAdmin) return@amIAnAdminIn
+                            runOnUiThread {
+                                val popupMenu = PopupMenu(this, groupMemberView)
+                                popupMenu.inflate(R.menu.user_pop_menu)
+                                popupMenu.setOnMenuItemClickListener { item ->
+                                    when (item.itemId) {
+                                        R.id.kick -> {
+
+                                            setUpMembers()
+                                            false
+                                        }
+
+                                        R.id.transfer_ownership -> {
+                                            AlertDialog.Builder(this)
+                                                .setMessage(getString(R.string.transfer_ownership_confirmation))
+                                                .setPositiveButton(R.string.yes) { _, _ ->
+                                                    net.transfer_ownership(
+                                                        groupId,
+                                                        (view as GroupMemberView).userId,
+                                                        { response ->
+                                                            runOnUiThread {
+                                                                Toast.makeText(
+                                                                    this,
+                                                                    response.body!!.string(),
+                                                                    Toast.LENGTH_SHORT
+                                                                ).show()
+                                                                setUpAdminRelatedButtons()
+                                                            }
+                                                        })
+
+                                                }
+                                                .setNegativeButton(R.string.no) { _, _ -> }
+                                                .show()
+                                            true
+                                        }
+
+                                        else -> false
+                                    }
+                                }
+                                runOnUiThread {
+                                    popupMenu.show()
+                                }
+                            }
+                        })
+                        true
+                    }
+                    runOnUiThread {
+                        binding.groupsContent.addView(groupMemberView)
+                    }
+                })
+            }
+        })
+    }
+
+    fun amIAnAdminIn(groupId: Int, callback: (Boolean) -> Unit) {
+        val net = Net()
+
+        net.token = sharedPreferences.getString("token", "")!!
+        net.server = sharedPreferences.getString("server", "")!!
+        net.language = sharedPreferences.getString("language", "en-US")!!
+
+        net.getGroupAdminId(groupId, { response ->
+            val result = sharedPreferences.getInt("userId", 0) == response.body!!.string().toInt()
+            callback(result)
+        })
+    }
+
+    fun setUpAdminRelatedButtons() {
+        amIAnAdminIn(groupId, { isAdmin ->
+            runOnUiThread {
+                if (!isAdmin) {
+                    binding.renameButton.visibility = View.GONE
+                }
+            }
+        })
+    }
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/activities/MyGroupsActivity.kt

@@ -0,0 +1,55 @@
+package org.foxarmy.barcodescannerforemployees.activities
+
+import android.content.Context
+import android.content.Intent
+import android.os.Bundle
+import android.widget.LinearLayout
+import androidx.appcompat.app.AppCompatActivity
+import org.foxarmy.barcodescannerforemployees.Net
+import org.foxarmy.barcodescannerforemployees.R
+import org.foxarmy.barcodescannerforemployees.databinding.ActivityMyGroupsBinding
+import org.foxarmy.barcodescannerforemployees.parseIntArray
+import org.foxarmy.barcodescannerforemployees.views.GroupView
+
+class MyGroupsActivity : AppCompatActivity(){
+    private lateinit var binding: ActivityMyGroupsBinding
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        binding = ActivityMyGroupsBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+
+        val sharedPreferences = org.foxarmy.barcodescannerforemployees.getPreferences(this)
+
+        val net = Net()
+
+        net.token = sharedPreferences.getString("token", "")!!
+        net.server = sharedPreferences.getString("server", "")!!
+        net.language = sharedPreferences.getString("language", "en-US")!!
+
+        net.getMyGroups { response ->
+            val groups = parseIntArray(response.body!!.string())
+
+
+            val container = findViewById<LinearLayout>(R.id.groupsLayout)
+
+            for (group in groups) {
+                net.getGroupName(group, {response ->
+                    val groupView = GroupView(this, this as Context, response, group)
+
+                    runOnUiThread {
+                        container.addView(groupView)
+                    }
+                })
+            }
+
+            binding.newGroup.setOnClickListener {
+                runOnUiThread {
+                    val intent = Intent(this, GroupActivity::class.java)
+                    startActivity(intent)
+                }
+            }
+        }
+    }
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/activities/NavigatorActivity.kt

@@ -0,0 +1,68 @@
+package org.foxarmy.barcodescannerforemployees.activities
+
+import android.app.Activity
+import android.content.Intent
+import android.content.SharedPreferences
+import android.os.Bundle
+import org.foxarmy.barcodescannerforemployees.Net
+import org.foxarmy.barcodescannerforemployees.parseStringList
+
+class NavigatorActivity : Activity() {
+
+    private lateinit var sharedPreferences: SharedPreferences
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        sharedPreferences = org.foxarmy.barcodescannerforemployees.getPreferences(this)
+
+        var intent = Intent(this, MainActivity::class.java)
+
+        isInGroup { flag ->
+            if (!flag && !isOffline()) {
+                intent = Intent(this, GroupActivity::class.java)
+            }
+            if (!isAuthenticated() && !isOffline()) {
+                intent = Intent(this, LoginActivity::class.java);
+            }
+
+            runOnUiThread {
+                startActivity(intent);
+                finish();
+            }
+        }
+    }
+
+    private fun isOffline(): Boolean {
+        return sharedPreferences.getString("currentGroup", "")!! == "offline"
+    }
+
+    private fun isAuthenticated(): Boolean {
+        return sharedPreferences.getString("token", "") != ""
+    }
+
+    private fun isInGroup(callback: (Boolean) -> Unit) {
+        val groups = sharedPreferences.getStringSet("groups", emptySet())!!
+        if (groups.isEmpty()) {
+            if (sharedPreferences.getString("token", "")!! == "") callback(false)
+            val net = Net()
+            net.language = sharedPreferences.getString("language", "")!!
+            net.server = sharedPreferences.getString("server", "")!!
+            net.token = sharedPreferences.getString("token", "")!!
+
+            net.getMyGroups { response ->
+                val responseBody = response.body!!.string()
+                if (responseBody == "" || responseBody == "[]") callback(false)
+                val groupsFromServer = parseStringList(responseBody)
+                if (groupsFromServer.isNotEmpty()) {
+                    sharedPreferences.edit().putStringSet("groups", groupsFromServer.toSet()).apply()
+                    sharedPreferences.edit().putString("currentGroup", groupsFromServer[0]).apply()
+                    callback(true)
+                } else {
+                    callback(false)
+                }
+            }
+        }
+        callback(true)
+    }
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/activities/SettingsActivity.kt

@@ -0,0 +1,103 @@
+package org.foxarmy.barcodescannerforemployees.activities
+
+import android.app.Activity
+import android.content.SharedPreferences
+import android.os.Bundle
+import android.view.View
+import android.widget.ArrayAdapter
+import androidx.appcompat.app.AppCompatActivity
+import org.foxarmy.barcodescannerforemployees.Net
+import org.foxarmy.barcodescannerforemployees.databinding.ActivitySettingsBinding
+
+class SettingsActivity : AppCompatActivity() {
+    lateinit var binding: ActivitySettingsBinding
+    lateinit var sharedPreferences: SharedPreferences
+    lateinit var myGroups: List<String>
+    lateinit var currentGroup: String
+    lateinit var groupsNames: MutableList<String>
+    lateinit var namesMap: MutableMap<Int, String>
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        sharedPreferences = org.foxarmy.barcodescannerforemployees.getPreferences(this)
+
+        myGroups = sharedPreferences.getStringSet("groups", emptySet())!!.toList()
+        currentGroup = sharedPreferences.getString("currentGroup", "offline")!!
+        val net = Net()
+
+        net.token = sharedPreferences.getString("token", "")!!
+        net.language = sharedPreferences.getString("language", "")!!
+        net.server = sharedPreferences.getString("server", "")!!
+
+        binding = ActivitySettingsBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+
+        setUpImageCompressionSeekBar()
+
+
+        if (isOffline()) {
+            binding.currentGroupSetting.visibility = View.GONE
+        } else {
+            namesMap = mutableMapOf()
+
+            for (myGroup in myGroups) {
+                net.getGroupName(myGroup.toInt(), { name ->
+                    namesMap[myGroup.toInt()] = name
+                    fillUpCurrentGroupSpinner()
+                })
+            }
+        }
+
+        binding.saveButton.setOnClickListener {
+            net.getGroupId(binding.currentGroupSpinner.selectedItem.toString(), { groupId ->
+                sharedPreferences.edit().putString("currentGroup", groupId).apply()
+                sharedPreferences.edit().putInt("imageCompression", binding.imageCompressionFactorSeekBar.progress + 1)
+                    .apply()
+                runOnUiThread {
+                    setResult(Activity.RESULT_OK)
+                    finish()
+                }
+            })
+        }
+
+        binding.cancelButton.setOnClickListener {
+            setResult(Activity.RESULT_CANCELED)
+            finish()
+        }
+    }
+
+    private fun isOffline(): Boolean {
+        return sharedPreferences.getString("currentGroup", "offline") == "offline"
+    }
+
+    private fun setUpImageCompressionSeekBar() {
+        val compressionFactor = sharedPreferences.getInt("imageCompression", 1)
+        binding.imageCompressionFactorSeekBar.progress = compressionFactor - 1
+    }
+
+    private fun fillUpCurrentGroupSpinner() {
+        runOnUiThread {
+            if (currentGroup == "offline") {
+                binding.currentGroupSetting.visibility = View.GONE
+            }
+            groupsNames = mutableListOf()
+            groupsNames.clear()
+            val sortedMap = namesMap.entries.sortedBy { it.key }.associate { it.toPair() }
+            for ((id, name) in sortedMap) {
+                groupsNames.add(name)
+            }
+
+            val arrayAdapter =
+                ArrayAdapter(this, androidx.appcompat.R.layout.support_simple_spinner_dropdown_item, groupsNames)
+            arrayAdapter.setDropDownViewResource(androidx.appcompat.R.layout.support_simple_spinner_dropdown_item)
+            binding.currentGroupSpinner.adapter = arrayAdapter
+            if (myGroups.indexOf(currentGroup) < groupsNames.size) binding.currentGroupSpinner.setSelection(
+                myGroups.indexOf(
+                    currentGroup
+                )
+            )
+        }
+
+    }
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/database/AbstractProductDAO.kt

@@ -0,0 +1,348 @@
+package org.foxarmy.barcodescannerforemployees.database
+
+import android.content.ContentValues
+import android.content.Context
+import android.database.DatabaseUtils
+import android.provider.BaseColumns
+import org.foxarmy.barcodescannerforemployees.dataclasses.AbstractProduct
+import java.io.File
+
+class AbstractProductDAO(private val dbHelper: DBStorageController) {
+
+    fun getAllAbstractProductInCategory(id: Int): List<AbstractProduct> {
+
+        val db = dbHelper.readableDatabase
+
+        val result = mutableListOf<AbstractProduct>()
+
+        val projection = arrayOf(
+            BaseColumns._ID,
+            AbstractProductContract.AbstractProductEntry.BARCODE,
+            AbstractProductContract.AbstractProductEntry.PRODUCT_NAME,
+            AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME,
+            AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT,
+            AbstractProductContract.AbstractProductEntry.UNIT
+        )
+
+        val selection = "${AbstractProductContract.AbstractProductEntry.CATEGORY} = ?"
+        val selectionArgs = arrayOf(id.toString())
+
+        val cursor = db.query(
+            AbstractProductContract.AbstractProductEntry.TABLE_NAME,
+            projection,
+            selection,
+            selectionArgs,
+            null,
+            null,
+            null
+        )
+
+        with(cursor) {
+            while (moveToNext()) {
+                val abstractProductId = getInt(getColumnIndexOrThrow(android.provider.BaseColumns._ID))
+                val abstractProductBarcode =
+                    getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.BARCODE))
+                val abstractProductName =
+                    getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NAME))
+                val abstractProductNetWeight =
+                    getDouble(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT))
+                val abstractProductImageHash =
+                    getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME))
+                val abstractProductUnit =
+                    getInt(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.UNIT))
+
+                val abstractProduct = AbstractProduct(
+                    abstractProductId,
+                    abstractProductBarcode,
+                    abstractProductName,
+                    abstractProductNetWeight,
+                    abstractProductImageHash,
+                    category = id,
+                    abstractProductUnit
+                )
+
+                result.add(abstractProduct)
+            }
+        }
+
+        return result
+    }
+
+    fun getAmountOfAbstractProductsInCategory(id: Int): Int {
+        val db = dbHelper.readableDatabase
+        return DatabaseUtils.longForQuery(
+            db,
+            "SELECT COUNT(*) FROM ${AbstractProductContract.AbstractProductEntry.TABLE_NAME} WHERE ${AbstractProductContract.AbstractProductEntry.CATEGORY} = ?",
+            arrayOf(id.toString())
+        ).toInt()
+    }
+
+    fun eraseAbstractProduct(id: Int, context: Context) {
+
+        val db = dbHelper.writableDatabase
+
+        val projectionForAbstractProduct = arrayOf(
+            AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME
+        )
+
+        val selectionForAbstractProduct = "${BaseColumns._ID} = ?"
+        val selectionArgsForAbstractProduct = arrayOf(id.toString())
+        val cursorForAbstractProduct = db.query(
+            AbstractProductContract.AbstractProductEntry.TABLE_NAME,
+            projectionForAbstractProduct,
+            selectionForAbstractProduct,
+            selectionArgsForAbstractProduct,
+            null,
+            null,
+            null
+        )
+        var imageHash: String = ""
+
+        with(cursorForAbstractProduct) {
+            while (moveToNext()) {
+                val productImageHash =
+                    getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME))
+                imageHash = productImageHash
+            }
+        }
+        val picturesDir = File(context.filesDir, "pictures")
+        val thumbnailsDir = File(context.cacheDir, "thumbnails")
+
+        File(picturesDir, "$imageHash.png").delete()
+        File(thumbnailsDir, "$imageHash.webp").delete()
+
+        val projectionForProducts = arrayOf(BaseColumns._ID)
+        val selectionForProducts = "${ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID} = ?"
+        val selectionArgsForProducts = arrayOf(id.toString())
+
+        val cursorForProducts = db.query(
+            ProductContract.ProductEntry.TABLE_NAME,
+            projectionForProducts,
+            selectionForProducts,
+            selectionArgsForProducts,
+            null,
+            null,
+            null
+        )
+
+        with(cursorForProducts) {
+            while (moveToNext()) {
+                ProductDAO(dbHelper).eraseProduct(getInt(getColumnIndexOrThrow(android.provider.BaseColumns._ID)))
+            }
+        }
+
+        db.delete(AbstractProductContract.AbstractProductEntry.TABLE_NAME, BaseColumns._ID + "=" + id, null)
+    }
+
+    fun findAbstractProductByBarcode(barcode: String): AbstractProduct? {
+
+        val db = dbHelper.readableDatabase
+
+        var abstractProduct: AbstractProduct? = null
+        val projection = arrayOf(
+            BaseColumns._ID,
+            AbstractProductContract.AbstractProductEntry.PRODUCT_NAME,
+            AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME,
+            AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT,
+            AbstractProductContract.AbstractProductEntry.CATEGORY,
+            AbstractProductContract.AbstractProductEntry.UNIT
+        )
+
+        val selection = "${AbstractProductContract.AbstractProductEntry.BARCODE} = ?"
+        val selectionArgs = arrayOf(barcode)
+
+        val cursor = db.query(
+            AbstractProductContract.AbstractProductEntry.TABLE_NAME,
+            projection,
+            selection,
+            selectionArgs,
+            null,
+            null,
+            null
+        )
+
+        with(cursor) {
+            while (moveToNext()) {
+                val id = getInt(getColumnIndexOrThrow(BaseColumns._ID))
+                val productName =
+                    getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NAME))
+                val imageFilename =
+                    getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME))
+                val netWeight =
+                    getDouble(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT))
+                val category = getInt(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.CATEGORY))
+                val unit = getInt(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.UNIT))
+
+                abstractProduct = AbstractProduct(id, barcode, productName, netWeight, imageFilename, category, unit)
+            }
+        }
+
+        return abstractProduct
+    }
+
+    fun findAbstractProductById(id: Int): AbstractProduct? {
+
+        val db = dbHelper.readableDatabase
+
+        var abstractProduct: AbstractProduct? = null
+        val projection = arrayOf(
+            BaseColumns._ID,
+            AbstractProductContract.AbstractProductEntry.PRODUCT_NAME,
+            AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT,
+            AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME,
+            AbstractProductContract.AbstractProductEntry.CATEGORY,
+            AbstractProductContract.AbstractProductEntry.BARCODE,
+            AbstractProductContract.AbstractProductEntry.UNIT
+        )
+
+        val selection = "${BaseColumns._ID} = ?"
+        val selectionArgs = arrayOf(id.toString())
+
+        val cursor = db.query(
+            AbstractProductContract.AbstractProductEntry.TABLE_NAME,
+            projection,
+            selection,
+            selectionArgs,
+            null,
+            null,
+            null
+        )
+
+        with(cursor) {
+            while (moveToNext()) {
+                val productId = getInt(getColumnIndexOrThrow(android.provider.BaseColumns._ID))
+                val barcode = getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.BARCODE))
+                val name = getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NAME))
+                val netWeight =
+                    getDouble(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT))
+                val imageHash =
+                    getString((getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME)))
+                val category = getInt(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.CATEGORY))
+                val unit = getInt(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.UNIT))
+
+                abstractProduct = AbstractProduct(productId, barcode, name, netWeight, imageHash, category, unit)
+            }
+        }
+
+        return abstractProduct
+    }
+
+    fun addAbstractProduct(abstractProduct: AbstractProduct): Long {
+
+        val db = dbHelper.writableDatabase
+
+        val values = ContentValues().apply {
+            if (abstractProduct.id > 0) put(BaseColumns._ID, abstractProduct.id)
+            put(AbstractProductContract.AbstractProductEntry.BARCODE, abstractProduct.barcode)
+            put(AbstractProductContract.AbstractProductEntry.PRODUCT_NAME, abstractProduct.name)
+            put(AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT, abstractProduct.netWeight.toString())
+            put(AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME, abstractProduct.imageHash)
+            put(AbstractProductContract.AbstractProductEntry.CATEGORY, abstractProduct.category)
+            put(AbstractProductContract.AbstractProductEntry.UNIT, abstractProduct.unit)
+        }
+
+        val id = db.insert(AbstractProductContract.AbstractProductEntry.TABLE_NAME, null, values)
+        return id
+    }
+
+    fun updateAbstractProduct(abstractProduct: AbstractProduct) {
+
+        val db = dbHelper.writableDatabase
+
+        val values = ContentValues().apply {
+            put(BaseColumns._ID, abstractProduct.id)
+            put(AbstractProductContract.AbstractProductEntry.BARCODE, abstractProduct.barcode)
+            put(AbstractProductContract.AbstractProductEntry.PRODUCT_NAME, abstractProduct.name)
+            put(AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT, abstractProduct.netWeight.toString())
+            put(AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME, abstractProduct.imageHash)
+            put(AbstractProductContract.AbstractProductEntry.CATEGORY, abstractProduct.category)
+            put(AbstractProductContract.AbstractProductEntry.UNIT, abstractProduct.unit)
+        }
+
+        db.update(
+            AbstractProductContract.AbstractProductEntry.TABLE_NAME,
+            values,
+            "${BaseColumns._ID} = ?",
+            arrayOf(abstractProduct.id.toString())
+        )
+    }
+
+    fun getSortedListOfAbstractProducts(
+        selectedSort: Int,
+        filterBy: String,
+        filter: Array<String>
+    ): List<AbstractProduct> {
+
+        val db = dbHelper.readableDatabase
+
+        val abstractProducts = mutableListOf<AbstractProduct>()
+
+        val projection = arrayOf(
+            BaseColumns._ID,
+            AbstractProductContract.AbstractProductEntry.BARCODE,
+            AbstractProductContract.AbstractProductEntry.PRODUCT_NAME,
+            AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT,
+            AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME,
+            AbstractProductContract.AbstractProductEntry.CATEGORY,
+            AbstractProductContract.AbstractProductEntry.UNIT
+        )
+
+        var orderBy: String = ""
+        when (selectedSort) {
+            0 -> {
+                orderBy = "${AbstractProductContract.AbstractProductEntry.PRODUCT_NAME} ASC"
+            }
+
+            1 -> {
+                orderBy = "${AbstractProductContract.AbstractProductEntry.CATEGORY} ASC"
+            }
+        }
+
+        var selection = ""
+        var selectionArgs: Array<String>? = null
+
+        when (filterBy) {
+            "category" -> {
+                selection = "${AbstractProductContract.AbstractProductEntry.CATEGORY} = ?"
+                selectionArgs = filter
+            }
+
+            "barcodeless" -> {
+                selection = "${AbstractProductContract.AbstractProductEntry.BARCODE} = ? OR ${AbstractProductContract.AbstractProductEntry.BARCODE} = ? OR ${AbstractProductContract.AbstractProductEntry.BARCODE} = ?"
+                selectionArgs = filter
+            }
+        }
+
+
+        val cursor = db.query(
+            AbstractProductContract.AbstractProductEntry.TABLE_NAME,
+            projection,
+            selection,
+            selectionArgs,
+            null,
+            null,
+            orderBy
+        )
+
+        with(cursor) {
+            while (moveToNext()) {
+                val productId = getInt(getColumnIndexOrThrow(android.provider.BaseColumns._ID))
+                val barcode = getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.BARCODE))
+                val productName =
+                    getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NAME))
+                val netWeight =
+                    getDouble(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT))
+                val productImageHash =
+                    getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME))
+                val category = getInt(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.CATEGORY))
+                val unit = getInt(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.UNIT))
+
+                val product =
+                    AbstractProduct(productId, barcode, productName, netWeight, productImageHash, category, unit)
+
+                abstractProducts.add(product)
+            }
+        }
+        return abstractProducts
+    }
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/database/CategoryDAO.kt

@@ -0,0 +1,114 @@
+package org.foxarmy.barcodescannerforemployees.database
+
+import android.content.ContentValues
+import android.content.Context
+import android.provider.BaseColumns
+import org.foxarmy.barcodescannerforemployees.dataclasses.Category
+
+class CategoryDAO(private val dbHelper: DBStorageController) {
+    fun eraseCategory(id: Int, context: Context) {
+
+        val abstractProductDAO = AbstractProductDAO(dbHelper)
+        val db = dbHelper.writableDatabase
+
+        val productsInCategory = abstractProductDAO.getAllAbstractProductInCategory(id)
+
+        for (product in productsInCategory.iterator()) {
+            abstractProductDAO.eraseAbstractProduct(product.id, context)
+        }
+
+        db.delete(CategoriesContract.CategoryEntry.TABLE_NAME, BaseColumns._ID + "=" + id, null)
+    }
+
+    fun getCategoryNameById(id: Int): String {
+
+        val db = dbHelper.readableDatabase
+
+        var result = ""
+
+        val projection = arrayOf(CategoriesContract.CategoryEntry.CATEGORY_NAME)
+        val selection = "${BaseColumns._ID} = ?"
+        val selectionArgs = arrayOf(id.toString())
+
+        val cursor = db.query(
+            CategoriesContract.CategoryEntry.TABLE_NAME,
+            projection,
+            selection,
+            selectionArgs,
+            null,
+            null,
+            null
+        )
+
+        with(cursor) {
+            while (moveToNext()) {
+                result = getString(getColumnIndexOrThrow(CategoriesContract.CategoryEntry.CATEGORY_NAME))
+            }
+        }
+
+        return result
+    }
+
+    fun getAllCategories(): List<Category> {
+
+        val db = dbHelper.readableDatabase
+
+        val categories = mutableListOf<Category>()
+
+        val projection = arrayOf(
+            BaseColumns._ID,
+            CategoriesContract.CategoryEntry.CATEGORY_NAME
+        )
+
+        val cursor = db.query(
+            CategoriesContract.CategoryEntry.TABLE_NAME,
+            projection,
+            null,
+            null,
+            null,
+            null,
+            BaseColumns._ID + " ASC"
+        )
+
+        with(cursor) {
+            while (moveToNext()) {
+                val category = Category(
+                    getInt(getColumnIndexOrThrow(BaseColumns._ID)),
+                    getString(getColumnIndexOrThrow(CategoriesContract.CategoryEntry.CATEGORY_NAME))
+                )
+                categories.add(category)
+            }
+        }
+
+        return categories
+    }
+
+    fun addCategory(category: Category): Long {
+
+        val db = dbHelper.writableDatabase
+
+        val values = ContentValues().apply {
+            if (category.id > 0) put(BaseColumns._ID, category.id)
+            put(CategoriesContract.CategoryEntry.CATEGORY_NAME, category.name)
+        }
+
+        val id = db.insert(CategoriesContract.CategoryEntry.TABLE_NAME, null, values)
+
+        return id
+    }
+
+    fun updateCategory(category: Category) {
+
+        val db = dbHelper.writableDatabase
+
+        val values = ContentValues().apply {
+            put(CategoriesContract.CategoryEntry.CATEGORY_NAME, category.name)
+        }
+        db.update(
+            CategoriesContract.CategoryEntry.TABLE_NAME,
+            values,
+            "${BaseColumns._ID} = ?",
+            arrayOf(category.id.toString())
+        )
+    }
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/database/DBStorageController.kt

@@ -0,0 +1,82 @@
+package org.foxarmy.barcodescannerforemployees.database
+
+import android.content.Context
+import android.database.sqlite.SQLiteDatabase
+import android.database.sqlite.SQLiteOpenHelper
+import android.provider.BaseColumns
+
+object AbstractProductContract {
+    object AbstractProductEntry : BaseColumns {
+        const val TABLE_NAME = "abstract_products"
+        const val BARCODE = "barcode"
+        const val PRODUCT_NAME = "name"
+        const val PRODUCT_NET_WEIGHT = "net_weight"
+        const val IMAGE_FILENAME = "image_filename"
+        const val CATEGORY = "category"
+        const val UNIT = "unit"
+    }
+}
+
+object CategoriesContract {
+    object CategoryEntry : BaseColumns {
+        const val TABLE_NAME = "categories"
+        const val CATEGORY_NAME = "category_name"
+    }
+}
+
+object ProductContract {
+    object ProductEntry : BaseColumns {
+        const val TABLE_NAME = "products"
+        const val ABSTRACT_PRODUCT_ID = "abstract_product_id"
+        const val AMOUNT = "amount"
+        const val DATE_OF_PRODUCTION = "date_of_production"
+        const val EXPIRY_DATE = "expiry_date"
+    }
+}
+
+const val SQL_CREATE_ABSTRACT_PRODUCTS_TABLE =
+    "CREATE TABLE ${AbstractProductContract.AbstractProductEntry.TABLE_NAME} (" +
+            "${BaseColumns._ID} INTEGER PRIMARY KEY," +
+            "${AbstractProductContract.AbstractProductEntry.BARCODE} TEXT," +
+            "${AbstractProductContract.AbstractProductEntry.PRODUCT_NAME} TEXT," +
+            "${AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT} REAL," +
+            "${AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME} TEXT," +
+            "${AbstractProductContract.AbstractProductEntry.CATEGORY} INTEGER," +
+            "${AbstractProductContract.AbstractProductEntry.UNIT} INTEGER)"
+
+const val SQL_CREATE_PRODUCTS_TABLE =
+    "CREATE TABLE ${ProductContract.ProductEntry.TABLE_NAME} (" +
+            "${BaseColumns._ID} INTEGER PRIMARY KEY," +
+            "${ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID} INTEGER," +
+            "${ProductContract.ProductEntry.AMOUNT} INTEGER," +
+            "${ProductContract.ProductEntry.DATE_OF_PRODUCTION} INTEGER," +
+            "${ProductContract.ProductEntry.EXPIRY_DATE} INTGER)"
+
+const val SQL_CREATE_CATEGORIES_TABLE =
+    "CREATE TABLE ${CategoriesContract.CategoryEntry.TABLE_NAME} (" +
+            "${BaseColumns._ID} INTEGER PRIMARY KEY," +
+            "${CategoriesContract.CategoryEntry.CATEGORY_NAME} TEXT)"
+
+class DBStorageController(context: Context, dbname: String) :
+    SQLiteOpenHelper(context, dbname, null, DATABASE_VERSION) {
+
+        init {
+            DATABASE_NAME = "$dbname.db"
+        }
+
+    override fun onCreate(db: SQLiteDatabase) {
+
+        db.execSQL(SQL_CREATE_ABSTRACT_PRODUCTS_TABLE)
+        db.execSQL(SQL_CREATE_PRODUCTS_TABLE)
+        db.execSQL(SQL_CREATE_CATEGORIES_TABLE)
+    }
+
+    override fun onUpgrade(db: SQLiteDatabase?, oldV: Int, newV: Int) {
+        TODO("Not yet implemented")
+    }
+
+    companion object {
+        const val DATABASE_VERSION = 1
+        var DATABASE_NAME = "database.db"
+    }
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/database/ProductDAO.kt

@@ -0,0 +1,172 @@
+package org.foxarmy.barcodescannerforemployees.database
+
+import android.content.ContentValues
+import android.provider.BaseColumns
+import org.foxarmy.barcodescannerforemployees.dataclasses.Product
+
+class ProductDAO (private val dbHelper: DBStorageController) {
+
+    fun eraseProduct(id: Int) {
+
+        val db = dbHelper.writableDatabase
+
+        db.delete(ProductContract.ProductEntry.TABLE_NAME, BaseColumns._ID + "=" + id, null)
+    }
+
+    fun insertNewProduct(product: Product) : Long{
+
+        val db = dbHelper.writableDatabase
+
+        val values = ContentValues().apply {
+            if (product.id > 0) put(BaseColumns._ID, product.id)
+            put(ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID, product.abstractProductId)
+            put(ProductContract.ProductEntry.AMOUNT, product.amount)
+            put(ProductContract.ProductEntry.DATE_OF_PRODUCTION, product.dateOfProduction)
+            put(ProductContract.ProductEntry.EXPIRY_DATE, product.dateOfExpiry)
+        }
+
+        val id = db.insert(ProductContract.ProductEntry.TABLE_NAME, null, values)
+        return id
+    }
+
+    fun findAmountOfProductsWithExpiryDate(date: Long): Int {
+
+        val db = dbHelper.readableDatabase
+
+        var amount = 0
+
+        val projection = arrayOf(
+            ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID,
+            ProductContract.ProductEntry.AMOUNT,
+            ProductContract.ProductEntry.DATE_OF_PRODUCTION,
+        )
+
+        val selection = "${ProductContract.ProductEntry.EXPIRY_DATE} = ?"
+        val selectionArgs = arrayOf(date.toString())
+
+        val cursor =
+            db.query(ProductContract.ProductEntry.TABLE_NAME, projection, selection, selectionArgs, null, null, null)
+
+        with(cursor) {
+            while (moveToNext()) {
+                amount++
+            }
+        }
+
+        return amount
+    }
+
+    fun findAllExpiryDates(): Set<Long> {
+
+        val db = dbHelper.readableDatabase
+
+        val dates: MutableSet<Long> = mutableSetOf<Long>()
+
+        val projection = arrayOf(
+            ProductContract.ProductEntry.EXPIRY_DATE
+        )
+
+        val orderBy = "${ProductContract.ProductEntry.EXPIRY_DATE} ASC"
+
+        val cursor = db.query(ProductContract.ProductEntry.TABLE_NAME, projection, null, null, null, null, orderBy)
+
+        with(cursor) {
+            while (moveToNext()) {
+                dates.add(getLong(getColumnIndexOrThrow(ProductContract.ProductEntry.EXPIRY_DATE)))
+            }
+        }
+
+        return dates
+    }
+
+    fun updateProduct(product: Product) {
+
+        val db = dbHelper.writableDatabase
+
+        val values = ContentValues().apply {
+            put(BaseColumns._ID, product.id)
+            put(ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID, product.abstractProductId)
+            put(ProductContract.ProductEntry.AMOUNT, product.amount)
+            put(ProductContract.ProductEntry.DATE_OF_PRODUCTION, product.dateOfProduction)
+            put(ProductContract.ProductEntry.EXPIRY_DATE, product.dateOfExpiry)
+        }
+        db.update(
+            ProductContract.ProductEntry.TABLE_NAME,
+            values,
+            "${BaseColumns._ID} = ?",
+            arrayOf(product.id.toString())
+        )
+    }
+
+    fun getSortedListOfProducts(selectedSort: Int, filterBy: String, filter: String): List<Product> {
+
+        val db = dbHelper.readableDatabase
+
+        val products = mutableListOf<Product>()
+
+        val projection = arrayOf(
+            BaseColumns._ID,
+            ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID,
+            ProductContract.ProductEntry.AMOUNT,
+            ProductContract.ProductEntry.DATE_OF_PRODUCTION,
+            ProductContract.ProductEntry.EXPIRY_DATE,
+        )
+
+        var orderBy: String = ""
+
+        when (selectedSort) {
+            0 -> {
+                orderBy =
+                    "(SELECT ${AbstractProductContract.AbstractProductEntry.PRODUCT_NAME} FROM ${AbstractProductContract.AbstractProductEntry.TABLE_NAME} WHERE ${BaseColumns._ID} = ${ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID}) ASC"
+            }
+
+            1 -> {
+                orderBy =
+                    "(SELECT ${AbstractProductContract.AbstractProductEntry.CATEGORY} FROM ${AbstractProductContract.AbstractProductEntry.TABLE_NAME} WHERE ${BaseColumns._ID} = ${ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID}) ASC"
+            }
+
+            3 -> {
+                orderBy = "${ProductContract.ProductEntry.DATE_OF_PRODUCTION} ASC"
+            }
+
+            4 -> {
+                orderBy = "${ProductContract.ProductEntry.EXPIRY_DATE} ASC"
+            }
+        }
+
+        var selection: String? = null
+        var selectionArgs: Array<String>? = null
+
+        when (filterBy) {
+            "expiryDate" -> {
+                selection = "${ProductContract.ProductEntry.EXPIRY_DATE} = ?"
+                selectionArgs = arrayOf(filter)
+            }
+
+            "" -> {}
+        }
+
+        val cursor = db.query(ProductContract.ProductEntry.TABLE_NAME, projection, selection, selectionArgs, null, null, orderBy)
+
+        with(cursor) {
+            while (moveToNext()) {
+                val productId = getInt(getColumnIndexOrThrow(android.provider.BaseColumns._ID))
+                val abstractProductId =
+                    getInt(getColumnIndexOrThrow(ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID))
+                val amount = getInt(getColumnIndexOrThrow(ProductContract.ProductEntry.AMOUNT))
+                val dateOfProduction =
+                    getLong(getColumnIndexOrThrow(ProductContract.ProductEntry.DATE_OF_PRODUCTION))
+                val dateOfExpiry = getLong(getColumnIndexOrThrow(ProductContract.ProductEntry.EXPIRY_DATE))
+
+                val product = Product(productId, abstractProductId, amount, dateOfProduction, dateOfExpiry)
+
+                products.add(product)
+            }
+        }
+
+        products.sortWith(compareByDescending { it.freshness })
+
+        return products
+    }
+
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/dataclasses/AbstractProduct.kt

@@ -2,6 +2,8 @@ package org.foxarmy.barcodescannerforemployees.dataclasses
 
 import android.os.Parcel
 import android.os.Parcelable
+import org.foxarmy.barcodescannerforemployees.md5
+import org.json.JSONObject
 
 class AbstractProduct() : Parcelable {
     var id: Int = 0
@@ -32,6 +34,10 @@ class AbstractProduct() : Parcelable {
         unit = parcel.readInt()
     }
 
+    fun calculateHash(): String {
+        return "$id:$barcode:$name:${if (netWeight % 1 == 0.0) netWeight.toInt() else netWeight}:$imageHash:$category:$unit".md5()
+    }
+
     override fun writeToParcel(parcel: Parcel, flags: Int) {
         parcel.writeInt(id)
         parcel.writeString(barcode)
@@ -54,5 +60,17 @@ class AbstractProduct() : Parcelable {
         override fun newArray(size: Int): Array<AbstractProduct?> {
             return arrayOfNulls(size)
         }
+
+        fun createFromJSON(json: JSONObject): AbstractProduct {
+            return AbstractProduct(
+                json["local_id"].toString().toInt(),
+                json["barcode"].toString(),
+                json["name"].toString(),
+                json["net_weight"].toString().toDouble(),
+                json["image_filename"].toString(),
+                json["category"].toString().toInt(),
+                json["unit"].toString().toInt()
+            )
+        }
     }
 }

app/src/main/java/org/foxarmy/barcodescannerforemployees/dataclasses/Category.kt

@@ -2,6 +2,8 @@ package org.foxarmy.barcodescannerforemployees.dataclasses
 
 import android.os.Parcel
 import android.os.Parcelable
+import org.foxarmy.barcodescannerforemployees.md5
+import org.json.JSONObject
 
 class Category() : Parcelable {
     var id = 0
@@ -27,6 +29,10 @@ class Category() : Parcelable {
         return 0
     }
 
+    fun calculateHash(): String {
+        return "$id:$name".md5()
+    }
+
     companion object CREATOR : Parcelable.Creator<Category> {
         override fun createFromParcel(parcel: Parcel): Category {
             return Category(parcel)
@@ -35,5 +41,12 @@ class Category() : Parcelable {
         override fun newArray(size: Int): Array<Category?> {
             return arrayOfNulls(size)
         }
+
+        fun createFromJSON(json: JSONObject): Category {
+            return Category(
+                json["local_id"].toString().toInt(),
+                json["name"].toString()
+            )
+        }
     }
 }

app/src/main/java/org/foxarmy/barcodescannerforemployees/dataclasses/Product.kt

@@ -5,6 +5,9 @@ import android.os.Parcel
 import android.os.Parcelable
 import androidx.annotation.RequiresApi
 import org.foxarmy.barcodescannerforemployees.calculateProductFreshness
+import org.foxarmy.barcodescannerforemployees.convertToUnixEpochTimestamp
+import org.foxarmy.barcodescannerforemployees.md5
+import org.json.JSONObject
 
 class Product() : Parcelable {
     var id = 0
@@ -46,6 +49,10 @@ class Product() : Parcelable {
         return 0
     }
 
+    fun calculateHash(): String {
+        return "$id:$abstractProductId:$amount:$dateOfProduction:$dateOfExpiry".md5()
+    }
+
     companion object CREATOR : Parcelable.Creator<Product> {
         override fun createFromParcel(parcel: Parcel): Product {
             return Product(parcel)
@@ -54,5 +61,16 @@ class Product() : Parcelable {
         override fun newArray(size: Int): Array<Product?> {
             return arrayOfNulls(size)
         }
+
+        @RequiresApi(Build.VERSION_CODES.O)
+        fun createFromJSON(json: JSONObject): Product {
+            return Product(
+                json["local_id"].toString().toInt(),
+                json["abstract_product_id"].toString().toInt(),
+                json["amount"].toString().toInt(),
+                convertToUnixEpochTimestamp(json["date_of_production"].toString()),
+                convertToUnixEpochTimestamp(json["expiry_date"].toString())
+            )
+        }
     }
 }

app/src/main/java/org/foxarmy/barcodescannerforemployees/fragments/CategoriesFragment.kt

@@ -1,8 +1,8 @@
 package org.foxarmy.barcodescannerforemployees.fragments
 
 import android.content.Intent
+import android.content.SharedPreferences
 import android.os.Bundle
-import android.provider.BaseColumns
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
@@ -11,14 +11,34 @@ import android.widget.Toast
 import androidx.core.content.ContextCompat
 import androidx.core.view.children
 import androidx.fragment.app.Fragment
-import org.foxarmy.barcodescannerforemployees.CategoriesContract
-import org.foxarmy.barcodescannerforemployees.DBStorageController
+import org.foxarmy.barcodescannerforemployees.Net
 import org.foxarmy.barcodescannerforemployees.R
 import org.foxarmy.barcodescannerforemployees.activities.AddCategoryActivity
-import org.foxarmy.barcodescannerforemployees.dataclasses.Category
+import org.foxarmy.barcodescannerforemployees.database.CategoryDAO
+import org.foxarmy.barcodescannerforemployees.database.DBStorageController
+import org.foxarmy.barcodescannerforemployees.getPreferences
 import org.foxarmy.barcodescannerforemployees.views.CategoryView
+import kotlin.concurrent.thread
 
 class CategoriesFragment : Fragment() {
+
+    private lateinit var sharedPreferences: SharedPreferences
+    private lateinit var categoryDAO: CategoryDAO
+    private var updateInProgress = false
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        sharedPreferences = getPreferences(requireContext())
+
+        prepareDatabaseConnection()
+    }
+
+    private fun prepareDatabaseConnection() {
+        val dbHelper = DBStorageController(requireContext(), sharedPreferences.getString("currentGroup", "offline")!!)
+        categoryDAO = CategoryDAO(dbHelper)
+    }
+
     override fun onCreateView(
         inflater: LayoutInflater, container: ViewGroup?,
         savedInstanceState: Bundle?
@@ -33,59 +53,75 @@ class CategoriesFragment : Fragment() {
     }
 
     fun removeSelected() {
-        val layout = view?.findViewById<LinearLayout>(R.id.categoriesLayout)
+        thread {
+            val layout = view?.findViewById<LinearLayout>(R.id.categoriesLayout)
 
-        val db = DBStorageController(requireContext())
-        var deleted = false
-        for (view: CategoryView in layout?.children!!.iterator() as Iterator<CategoryView>) {
-            if (view.isCategorySelected) {
-                db.eraseCategory(db.writableDatabase, view.category.id, requireContext())
-                deleted = true
+            var deleted = false
+            for (view: CategoryView in layout?.children!!.iterator() as Iterator<CategoryView>) {
+                if (view.isCategorySelected) {
+                    val net = Net()
+                    net.token = sharedPreferences.getString("token", "")!!
+                    net.server = sharedPreferences.getString("server", "")!!
+                    net.language = sharedPreferences.getString("language", "en-US")!!
+                    val currentGroup = sharedPreferences.getString("currentGroup", "")!!.toInt()
+
+                    categoryDAO.eraseCategory(view.category.id, requireContext())
+                    net.deleteCategory(currentGroup, view.category.id, {response ->
+                        activity!!.runOnUiThread{
+                            Toast.makeText(context, response.body!!.string(), Toast.LENGTH_SHORT).show()
+                        }
+
+                    })
+                    deleted = true
+                }
             }
-        }
 
-        if (!deleted) {
-            Toast.makeText(requireContext(), getString(R.string.nothing_to_delete), Toast.LENGTH_SHORT).show()
+            if (!deleted) {
+                activity!!.runOnUiThread {
+                    Toast.makeText(requireContext(), getString(R.string.nothing_to_delete), Toast.LENGTH_SHORT).show()
+                }
+            }
+            updateContent()
         }
-        updateContent()
     }
 
     fun updateSelected() {
-        val layout = view?.findViewById<LinearLayout>(R.id.categoriesLayout)
-        for (view: CategoryView in layout?.children!!.iterator() as Iterator<CategoryView>) {
-            if (view.isCategorySelected) {
-                val addCategoryIntent = Intent(context, AddCategoryActivity::class.java)
-                val extras = Bundle()
-                extras.putParcelable("category", view.category)
-                addCategoryIntent.putExtras(extras)
-                ContextCompat.startActivity(context!!, addCategoryIntent, extras)
+        thread {
+            val layout = view?.findViewById<LinearLayout>(R.id.categoriesLayout)
+            for (view: CategoryView in layout?.children!!.iterator() as Iterator<CategoryView>) {
+                if (view.isCategorySelected) {
+                    val addCategoryIntent = Intent(context, AddCategoryActivity::class.java)
+                    val extras = Bundle()
+                    extras.putParcelable("category", view.category)
+                    addCategoryIntent.putExtras(extras)
+                    activity!!.runOnUiThread {
+                        ContextCompat.startActivity(context!!, addCategoryIntent, extras)
+                    }
+                }
             }
         }
     }
 
     fun updateContent() {
-        val layout = view?.findViewById<LinearLayout>(R.id.categoriesLayout)
-        layout?.removeAllViews()
-
-        val db = DBStorageController(requireContext()).readableDatabase
-
-        val projection = arrayOf(
-            BaseColumns._ID,
-            CategoriesContract.CategoryEntry.CATEGORY_NAME
-        )
-
-        val cursor = db.query(CategoriesContract.CategoryEntry.TABLE_NAME, projection, null, null, null, null, null)
-
-        with (cursor) {
-            while(moveToNext()) {
-                val categoryId = getInt(getColumnIndexOrThrow(BaseColumns._ID))
-                val categoryName = getString(getColumnIndexOrThrow(CategoriesContract.CategoryEntry.CATEGORY_NAME))
-
-                val category = Category(categoryId, categoryName)
-
-                val categoryView = CategoryView(requireActivity(), requireContext(), category)
-                layout?.addView(categoryView)
+        thread {
+            if (updateInProgress) return@thread
+            updateInProgress = true
+            prepareDatabaseConnection()
+            val layout = view?.findViewById<LinearLayout>(R.id.categoriesLayout)
+            activity!!.runOnUiThread {
+                layout?.removeAllViews()
             }
+
+            val categories = categoryDAO.getAllCategories()
+
+            for (category in categories) {
+                val categoryView = CategoryView(requireActivity(), requireContext(), category)
+                activity!!.runOnUiThread {
+                    layout?.addView(categoryView)
+                }
+            }
+
+            updateInProgress = false
         }
     }
 

app/src/main/java/org/foxarmy/barcodescannerforemployees/fragments/ShelfFragment.kt

@@ -1,9 +1,8 @@
 package org.foxarmy.barcodescannerforemployees.fragments
 
-import android.content.Context
 import android.content.Intent
+import android.content.SharedPreferences
 import android.os.Bundle
-import android.provider.BaseColumns
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
@@ -15,13 +14,13 @@ import androidx.core.content.ContextCompat
 import androidx.core.view.children
 import androidx.fragment.app.Fragment
 import androidx.gridlayout.widget.GridLayout
-import org.foxarmy.barcodescannerforemployees.AbstractProductContract
-import org.foxarmy.barcodescannerforemployees.DBStorageController
-import org.foxarmy.barcodescannerforemployees.ProductContract
+import org.foxarmy.barcodescannerforemployees.Net
 import org.foxarmy.barcodescannerforemployees.R
 import org.foxarmy.barcodescannerforemployees.activities.AddProductActivity
+import org.foxarmy.barcodescannerforemployees.database.DBStorageController
+import org.foxarmy.barcodescannerforemployees.database.ProductDAO
 import org.foxarmy.barcodescannerforemployees.databinding.FragmentShelfBinding
-import org.foxarmy.barcodescannerforemployees.dataclasses.Product
+import org.foxarmy.barcodescannerforemployees.getPreferences
 import org.foxarmy.barcodescannerforemployees.views.ProductView
 import kotlin.concurrent.thread
 
@@ -32,6 +31,17 @@ class ShelfFragment : Fragment() {
     private var filterBy = ""
     private var filter = ""
 
+    private lateinit var productDAO: ProductDAO
+    private lateinit var sharedPreferences: SharedPreferences
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        sharedPreferences = getPreferences(requireContext())
+
+        prepareDatabaseConnection()
+    }
+
     override fun onCreateView(
         inflater: LayoutInflater, container: ViewGroup?,
         savedInstanceState: Bundle?
@@ -61,6 +71,11 @@ class ShelfFragment : Fragment() {
         return binding.root
     }
 
+    private fun prepareDatabaseConnection() {
+        val dbHelper = DBStorageController(requireContext(), sharedPreferences.getString("currentGroup", "database")!!)
+        productDAO = ProductDAO(dbHelper)
+    }
+
     fun updateSelected() {
         val grv = view?.findViewById<GridLayout>(R.id.contentGridLayout)
 
@@ -102,93 +117,14 @@ class ShelfFragment : Fragment() {
         thread {
             if (updateInProgress) return@thread
             updateInProgress = true
+            prepareDatabaseConnection()
             val grv = view?.findViewById<GridLayout>(R.id.contentGridLayout)
+
             activity!!.runOnUiThread {
                 grv?.removeAllViews()
             }
 
-            val db = DBStorageController(requireContext()).readableDatabase
-            val projection = arrayOf(
-                BaseColumns._ID,
-                ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID,
-                ProductContract.ProductEntry.AMOUNT,
-                ProductContract.ProductEntry.DATE_OF_PRODUCTION,
-                ProductContract.ProductEntry.EXPIRY_DATE,
-            )
-
-            var orderBy: String = ""
-
-            when (binding.spinner.selectedItemPosition) {
-                0 -> {
-                    orderBy =
-                        "(SELECT ${AbstractProductContract.AbstractProductEntry.PRODUCT_NAME} FROM ${AbstractProductContract.AbstractProductEntry.TABLE_NAME} WHERE ${BaseColumns._ID} = ${ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID}) ASC"
-                }
-
-                1 -> {
-                    orderBy =
-                        "(SELECT ${AbstractProductContract.AbstractProductEntry.CATEGORY} FROM ${AbstractProductContract.AbstractProductEntry.TABLE_NAME} WHERE ${BaseColumns._ID} = ${ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID}) ASC"
-                }
-// Wow, I wrote this on first try but unfortunately SQLite can't do that :(
-// I'll leave it here as a memory.
-//                "Freshness" -> {
-//                    orderBy =
-//                        "(SELECT ( (julianday(${ProductContract.ProductEntry.EXPIRY_DATE}) - julianday('now', 'localtime')) / (julianday(${ProductContract.ProductEntry.EXPIRY_DATE}) - julianday(${ProductContract.ProductEntry.DATE_OF_PRODUCTION})) )) ASC"
-//                }
-
-                3 -> {
-                    orderBy = "${ProductContract.ProductEntry.DATE_OF_PRODUCTION} ASC"
-                }
-
-                4 -> {
-                    orderBy = "${ProductContract.ProductEntry.EXPIRY_DATE} ASC"
-                }
-            }
-
-            var selection: String? = null
-            var selectionArgs: Array<String>? = null
-
-            when (filterBy) {
-                "expiryDate" -> {
-                    selection = "${ProductContract.ProductEntry.EXPIRY_DATE} = ?"
-                    selectionArgs = arrayOf(filter)
-                }
-
-                "" -> {}
-            }
-
-
-            val cursor = db.query(ProductContract.ProductEntry.TABLE_NAME, projection, selection, selectionArgs, null, null, orderBy)
-
-            val products = mutableListOf<Product>()
-
-            with(cursor) {
-                while (moveToNext()) {
-                    val productId = getInt(getColumnIndexOrThrow(BaseColumns._ID))
-                    val abstractProductId =
-                        getInt(getColumnIndexOrThrow(ProductContract.ProductEntry.ABSTRACT_PRODUCT_ID))
-                    val amount = getInt(getColumnIndexOrThrow(ProductContract.ProductEntry.AMOUNT))
-                    val dateOfProduction =
-                        getLong(getColumnIndexOrThrow(ProductContract.ProductEntry.DATE_OF_PRODUCTION))
-                    val dateOfExpiry = getLong(getColumnIndexOrThrow(ProductContract.ProductEntry.EXPIRY_DATE))
-
-                    val product = Product(productId, abstractProductId, amount, dateOfProduction, dateOfExpiry)
-
-                    if (binding.spinner.selectedItemPosition == 2) { //freshness
-                        products.add(product)
-                    } else {
-                        val productView = ProductView(
-                            requireActivity(),
-                            requireContext(),
-                            product
-                        )
-                        activity!!.runOnUiThread {
-                            grv?.addView(productView)
-                        }
-                    }
-                }
-            }
-
-            products.sortWith(compareByDescending { it.freshness })
+            val products = productDAO.getSortedListOfProducts(binding.spinner.selectedItemPosition, filterBy, filter)
 
             for (product in products.iterator()) {
                 val productView = ProductView(
@@ -208,14 +144,25 @@ class ShelfFragment : Fragment() {
         thread {
             val grv = view?.findViewById<GridLayout>(R.id.contentGridLayout)
 
-            val db = DBStorageController(requireContext())
             var deleted = false
             for (view: ProductView in grv?.children!!.iterator() as Iterator<ProductView>) {
                 activity!!.runOnUiThread {
                     view.findViewById<ImageView>(R.id.productPicture).setImageURI(null)
                 }
                 if (view.isProductSelected) {
-                    db.eraseProduct(db.writableDatabase, view.product.id)
+                    val net = Net()
+                    net.token = sharedPreferences.getString("token", "")!!
+                    net.server = sharedPreferences.getString("server", "")!!
+                    net.language = sharedPreferences.getString("language", "en-US")!!
+                    val currentGroup = sharedPreferences.getString("currentGroup", "")!!.toInt()
+
+                    productDAO.eraseProduct(view.product.id)
+                    net.deleteProduct(currentGroup, view.product.id, {response ->
+                        activity!!.runOnUiThread{
+                            Toast.makeText(context, response.body!!.string(), Toast.LENGTH_SHORT).show()
+                        }
+                    })
+                    
                     deleted = true
                 }
             }

app/src/main/java/org/foxarmy/barcodescannerforemployees/fragments/StorageFragment.kt

@@ -1,23 +1,25 @@
 package org.foxarmy.barcodescannerforemployees.fragments
 
 import android.content.Intent
+import android.content.SharedPreferences
 import android.os.Bundle
-import android.provider.BaseColumns
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import android.widget.*
+import androidx.constraintlayout.widget.ConstraintLayout
 import androidx.core.content.ContextCompat
 import androidx.core.view.children
 import androidx.fragment.app.Fragment
-import org.foxarmy.barcodescannerforemployees.AbstractProductContract
-import org.foxarmy.barcodescannerforemployees.DBStorageController
+import org.foxarmy.barcodescannerforemployees.Net
 import org.foxarmy.barcodescannerforemployees.R
 import org.foxarmy.barcodescannerforemployees.activities.AddAbstractProductActivity
 import org.foxarmy.barcodescannerforemployees.activities.FindBarcodelessAbstractProduct
+import org.foxarmy.barcodescannerforemployees.database.AbstractProductDAO
+import org.foxarmy.barcodescannerforemployees.database.DBStorageController
 import org.foxarmy.barcodescannerforemployees.databinding.FragmentStorageBinding
-import org.foxarmy.barcodescannerforemployees.dataclasses.AbstractProduct
 import org.foxarmy.barcodescannerforemployees.generateThumbnailForImage
+import org.foxarmy.barcodescannerforemployees.getPreferences
 import org.foxarmy.barcodescannerforemployees.views.AbstractProductView
 import kotlin.concurrent.thread
 
@@ -26,12 +28,22 @@ class StorageFragment : Fragment() {
     private lateinit var binding: FragmentStorageBinding
     private var filterBy = ""
     private lateinit var filter: Array<String>
+
+    private lateinit var sharedPreferences: SharedPreferences
+    private lateinit var abstractProductDAO: AbstractProductDAO
+
+    private var updateInProcess = false
+
     override fun onCreateView(
         inflater: LayoutInflater, container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View {
         binding = FragmentStorageBinding.inflate(inflater)
 
+        sharedPreferences = getPreferences(requireContext())
+
+        prepareDatabaseConnection()
+
         fillUpSortBySpinner()
 
         binding.spinner.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
@@ -55,6 +67,11 @@ class StorageFragment : Fragment() {
         return binding.root
     }
 
+    private fun prepareDatabaseConnection() {
+        val dbHelper = DBStorageController(requireContext(), sharedPreferences.getString("currentGroup", "database")!!)
+        abstractProductDAO = AbstractProductDAO(dbHelper)
+    }
+
     override fun onResume() {
         super.onResume()
 
@@ -72,14 +89,26 @@ class StorageFragment : Fragment() {
         thread {
             val grv = binding.contentGridLayout
 
-            val db = DBStorageController(requireContext())
             var deleted = false
             for (view: AbstractProductView in grv.children.iterator() as Iterator<AbstractProductView>) {
                 activity!!.runOnUiThread {
                     view.findViewById<ImageView>(R.id.productPicture).setImageURI(null)
                 }
                 if (view.isProductSelected) {
-                    db.eraseAbstractProduct(db.writableDatabase, view.abstractProduct.id, requireContext())
+                    val net = Net()
+                    net.token = sharedPreferences.getString("token", "")!!
+                    net.server = sharedPreferences.getString("server", "")!!
+                    net.language = sharedPreferences.getString("language", "en-US")!!
+                    val currentGroup = sharedPreferences.getString("currentGroup", "")!!.toInt()
+
+                    abstractProductDAO.eraseAbstractProduct(view.abstractProduct.id, requireContext())
+                    net.deleteAbstractProduct(currentGroup, view.abstractProduct.id, {response ->
+                        activity!!.runOnUiThread{
+                            Toast.makeText(context, response.body!!.string(), Toast.LENGTH_SHORT).show()
+                        }
+                    })
+
+
                     deleted = true
                 }
             }
@@ -110,98 +139,65 @@ class StorageFragment : Fragment() {
 
     fun updateContent() {
         thread {
+            if (updateInProcess) return@thread
+            updateInProcess = true
+            prepareDatabaseConnection()
+
             val grv = binding.contentGridLayout
-            activity!!.runOnUiThread{
+
+            activity!!.runOnUiThread {
                 grv.removeAllViews()
             }
 
-            val db = DBStorageController(requireContext()).readableDatabase
-            val projection = arrayOf(
-                BaseColumns._ID,
-                AbstractProductContract.AbstractProductEntry.BARCODE,
-                AbstractProductContract.AbstractProductEntry.PRODUCT_NAME,
-                AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT,
-                AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME,
-                AbstractProductContract.AbstractProductEntry.CATEGORY,
-                AbstractProductContract.AbstractProductEntry.UNIT
-            )
+            val abstractProducts = abstractProductDAO.getSortedListOfAbstractProducts(binding.spinner.selectedItemPosition, filterBy, filter)
 
-            var orderBy: String = ""
-            when(binding.spinner.selectedItemPosition) {
-                0 -> {
-                    orderBy = "${AbstractProductContract.AbstractProductEntry.PRODUCT_NAME} ASC"
-                }
-                1 -> {
-                    orderBy = "${AbstractProductContract.AbstractProductEntry.CATEGORY} ASC"
-                }
-            }
+            for (abstractProduct in abstractProducts) {
+                generateThumbnailForImage(context!!, abstractProduct.imageHash)
 
-            var selection = ""
-            var selectionArgs: Array<String>? = null
+                val abstractProductView = AbstractProductView(
+                    requireActivity(),
+                    requireContext(),
+                    abstractProduct
+                )
 
-            when (filterBy) {
-                "category" -> {
-                    selection = "${AbstractProductContract.AbstractProductEntry.CATEGORY} = ?"
-                    selectionArgs = filter
-                }
-                "barcodeless" -> {
-                    selection = "${AbstractProductContract.AbstractProductEntry.BARCODE} = '' "
-                    selectionArgs = null
-                }
-            }
-
-
-            val cursor = db.query(AbstractProductContract.AbstractProductEntry.TABLE_NAME, projection, selection, selectionArgs, null, null, orderBy)
-
-            with (cursor) {
-                while(moveToNext()) {
-                    val productId = getInt(getColumnIndexOrThrow(BaseColumns._ID))
-                    val barcode = getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.BARCODE))
-                    val productName = getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NAME))
-                    val netWeight = getDouble(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT))
-                    val productImageHash = getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME))
-                    val category = getInt(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.CATEGORY))
-                    val unit = getInt(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.UNIT))
-
-                    val product = AbstractProduct(productId, barcode, productName, netWeight, productImageHash, category, unit)
-
-                    generateThumbnailForImage(context!!, productImageHash)
-
-                    val abstractProduct = AbstractProductView(
-                        requireActivity(),
-                        requireContext(),
-                        product
-                    )
-
-                    if (filterBy == "barcodeless") {
-                        abstractProduct.setOnClickListener {
-                            (activity as FindBarcodelessAbstractProduct).selected(abstractProduct.abstractProduct)
+                if (filterBy == "barcodeless") {
+                    abstractProductView.also {
+                        it.setOnClickListener {
+                            (activity as FindBarcodelessAbstractProduct).selected(abstractProductView.abstractProduct)
                         }
-                        abstractProduct.findViewById<TextView>(R.id.productNameView).setOnClickListener {
-                            (activity as FindBarcodelessAbstractProduct).selected(abstractProduct.abstractProduct)
-
+                        it.findViewById<TextView>(R.id.productNameView).setOnClickListener {
+                            (activity as FindBarcodelessAbstractProduct).selected(abstractProductView.abstractProduct)
+                        }
+                        it.findViewById<ConstraintLayout>(R.id.productLayout).setOnClickListener {
+                            (activity as FindBarcodelessAbstractProduct).selected(abstractProductView.abstractProduct)
+                        }
+                        it.findViewById<TextView>(R.id.categoryView).setOnClickListener {
+                            (activity as FindBarcodelessAbstractProduct).selected(abstractProductView.abstractProduct)
+                        }
+                        it.findViewById<TextView>(R.id.unitView).setOnClickListener {
+                            (activity as FindBarcodelessAbstractProduct).selected(abstractProductView.abstractProduct)
+                        }
+                        it.findViewById<TextView>(R.id.productNetWeightView).setOnClickListener {
+                            (activity as FindBarcodelessAbstractProduct).selected(abstractProductView.abstractProduct)
                         }
                     }
+                }
 
-                    activity!!.runOnUiThread{
-                        grv.addView(abstractProduct)
-                    }
+                activity!!.runOnUiThread{
+                    grv.addView(abstractProductView)
                 }
             }
-        }.join()
+            updateInProcess = false
+        }
     }
 
-    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
-        super.onViewCreated(view, savedInstanceState)
-
-        updateContent()
-    }
 
     fun filterByCategory(id: Int) {
         filterBy = "category"
         filter = arrayOf("$id")
         updateContent()
     }
+
     companion object {
 
         fun newInstance(filterBy: String, filter: Array<String>):StorageFragment = StorageFragment().apply {
@@ -209,7 +205,7 @@ class StorageFragment : Fragment() {
             val args = Bundle()
             args.putString("filterBy", filterBy)
             args.putStringArray("filter", filter)
-            fragment.setArguments(args)
+            fragment.arguments = args
 
             return fragment
         }

app/src/main/java/org/foxarmy/barcodescannerforemployees/views/AbstractProductView.kt

@@ -3,6 +3,7 @@ package org.foxarmy.barcodescannerforemployees.views
 import android.app.Activity
 import android.content.Context
 import android.content.Intent
+import android.content.SharedPreferences
 import android.os.Bundle
 import android.util.AttributeSet
 import android.view.LayoutInflater
@@ -15,10 +16,13 @@ import androidx.core.content.ContextCompat
 import androidx.core.content.ContextCompat.startActivity
 import org.foxarmy.barcodescannerforemployees.*
 import org.foxarmy.barcodescannerforemployees.activities.FullscreenActivity
+import org.foxarmy.barcodescannerforemployees.activities.MainActivity
+import org.foxarmy.barcodescannerforemployees.database.CategoryDAO
+import org.foxarmy.barcodescannerforemployees.database.DBStorageController
 import org.foxarmy.barcodescannerforemployees.dataclasses.AbstractProduct
 import java.io.File
 
-class AbstractProductView: LinearLayout {
+class AbstractProductView : LinearLayout {
     private var productLayout: ConstraintLayout? = null
     private var productPicture: ImageView? = null
     private var productNameField: TextView? = null
@@ -27,24 +31,36 @@ class AbstractProductView: LinearLayout {
     private var unitField: TextView? = null
     var abstractProduct: AbstractProduct = AbstractProduct()
     var isProductSelected = false
-    private lateinit var activity: Activity
+    private var activity: Activity
+
+    private var categoryDAO: CategoryDAO
+    private var sharedPreferences: SharedPreferences
 
     constructor(context: Context, a: AttributeSet) : super(context, a) {
         activity = getActivity(context)!!
-        val inflater:LayoutInflater = activity.layoutInflater
+        val inflater: LayoutInflater = activity.layoutInflater
         inflater.inflate(R.layout.abstract_product_view, this)
+
+        sharedPreferences = getPreferences(context)
+
+        val dbHelper = DBStorageController(context, sharedPreferences.getString("currentGroup", "database")!!)
+        categoryDAO = CategoryDAO(dbHelper)
     }
 
     constructor(activity: Activity, context: Context, abstractProduct: AbstractProduct) : super(context) {
         this.abstractProduct = abstractProduct
         this.activity = activity
-        val inflater:LayoutInflater = activity.layoutInflater
+        val inflater: LayoutInflater = activity.layoutInflater
         inflater.inflate(R.layout.abstract_product_view, this)
 
+        sharedPreferences = getPreferences(context)
+
+        val dbHelper = DBStorageController(context, sharedPreferences.getString("currentGroup", "database")!!)
+        categoryDAO = CategoryDAO(dbHelper)
         update()
     }
 
-    fun init () {
+    private fun init() {
         productLayout = findViewById(R.id.productLayout)
         productPicture = findViewById(R.id.productPicture)
         productNameField = findViewById(R.id.productNameView)
@@ -52,30 +68,8 @@ class AbstractProductView: LinearLayout {
         categoryField = findViewById(R.id.categoryView)
         unitField = findViewById(R.id.unitView)
 
-
-        productPicture!!.setOnClickListener {
-            val fullscreenIntent = Intent(activity, FullscreenActivity::class.java)
-            val extras = Bundle()
-            extras.putString("imagehash", abstractProduct.imageHash)
-            fullscreenIntent.putExtras(extras)
-            startActivity(context, fullscreenIntent, extras)
-        }
-
-        productLayout!!.setOnClickListener {
-
-        }
-
+        setUpClicks()
         unitField?.text = getUnitNameById(context, abstractProduct.unit)
-
-        productLayout!!.setOnLongClickListener {
-            isProductSelected = !isProductSelected
-            this.background = ContextCompat.getDrawable(context, if (isProductSelected) R.drawable.outline_selected else R.drawable.outline)
-            true
-        }
-
-        productNameField!!.setOnClickListener {
-            Toast.makeText(activity, productNameField!!.text, Toast.LENGTH_SHORT).show()
-        }
     }
 
     fun update() {
@@ -85,10 +79,126 @@ class AbstractProductView: LinearLayout {
         thumbnailsDir.mkdirs()
         val imageUri = getImageUri(activity, File(thumbnailsDir, "${abstractProduct.imageHash}.webp"))
         productPicture!!.setImageURI(imageUri)
-//        productPicture!!.rotation = 90f
 
         productNameField!!.text = abstractProduct.name
         netWeightField!!.text = abstractProduct.netWeight.toString()
-        categoryField!!.text = DBStorageController(context).getCategoryNameById(DBStorageController(context).readableDatabase, abstractProduct.category)
+        categoryField!!.text = categoryDAO.getCategoryNameById(abstractProduct.category)
+    }
+
+
+    private fun setUpClicks() {
+        productLayout!!.setOnLongClickListener { onAnyLongClick() }
+        productNameField!!.setOnLongClickListener { onNameLongClick() }
+        productPicture!!.setOnLongClickListener { onImageLongClick() }
+        netWeightField!!.setOnLongClickListener { onAnyLongClick() }
+        categoryField!!.setOnLongClickListener { onAnyLongClick() }
+        unitField!!.setOnLongClickListener { onAnyLongClick() }
+
+        productLayout!!.setOnClickListener { onAnyClick() }
+        netWeightField!!.setOnClickListener { onAnyClick() }
+        categoryField!!.setOnClickListener { onAnyClick() }
+        unitField!!.setOnClickListener { onAnyClick() }
+        productPicture!!.setOnClickListener { onImageLongClick() }
+        productNameField!!.setOnClickListener { onNameLongClick() }
+    }
+
+    private fun onAnyClick(): Boolean {
+        if (activity !is MainActivity) return false
+        val mainActivity = activity as MainActivity
+
+        if (mainActivity.selectionMode) {
+            isProductSelected = !isProductSelected
+
+            if (isProductSelected) {
+                mainActivity.addSelection()
+            } else {
+                mainActivity.removeSelection()
+            }
+            activity.runOnUiThread {
+                this.background = ContextCompat.getDrawable(
+                    context,
+                    if (isProductSelected) R.drawable.outline_selected else R.drawable.outline
+                )
+            }
+            return true
+        } else {
+            return false
+        }
+    }
+
+    private fun onAnyLongClick(): Boolean {
+        if (activity !is MainActivity) return false
+        val mainActivity = activity as MainActivity
+
+        if (mainActivity.selectionMode) {
+            isProductSelected = !isProductSelected
+
+            if (isProductSelected) {
+                mainActivity.addSelection()
+            } else {
+                mainActivity.removeSelection()
+            }
+            activity.runOnUiThread {
+                this.background = ContextCompat.getDrawable(
+                    context,
+                    if (isProductSelected) R.drawable.outline_selected else R.drawable.outline
+                )
+            }
+            return true
+        } else {
+            mainActivity.addSelection()
+
+            isProductSelected = !isProductSelected
+            activity.runOnUiThread {
+
+                this.background = ContextCompat.getDrawable(
+                    context,
+                    if (isProductSelected) R.drawable.outline_selected else R.drawable.outline
+                )
+            }
+            return true
+        }
+    }
+
+    private fun onImageLongClick(): Boolean {
+        if (activity !is MainActivity) {
+            val fullscreenIntent = Intent(activity, FullscreenActivity::class.java)
+            val extras = Bundle()
+            extras.putString("imagehash", abstractProduct.imageHash)
+            fullscreenIntent.putExtras(extras)
+            startActivity(context, fullscreenIntent, extras)
+            return true
+        }
+        val mainActivity = activity as MainActivity
+
+        if (mainActivity.selectionMode) {
+            return onAnyLongClick()
+        } else {
+            val fullscreenIntent = Intent(activity, FullscreenActivity::class.java)
+            val extras = Bundle()
+            extras.putString("imagehash", abstractProduct.imageHash)
+            fullscreenIntent.putExtras(extras)
+            startActivity(context, fullscreenIntent, extras)
+        }
+        return true
+    }
+
+    private fun onNameLongClick(): Boolean {
+        if (activity !is MainActivity) {
+            activity.runOnUiThread {
+                Toast.makeText(activity, productNameField!!.text, Toast.LENGTH_SHORT).show()
+            }
+            return true
+        }
+        val mainActivity = activity as MainActivity
+
+        if (mainActivity.selectionMode) {
+            return onAnyLongClick()
+        } else {
+            activity.runOnUiThread {
+                Toast.makeText(activity, productNameField!!.text, Toast.LENGTH_SHORT).show()
+            }
+        }
+        return true
     }
 }

app/src/main/java/org/foxarmy/barcodescannerforemployees/views/CategoryView.kt

@@ -2,42 +2,88 @@ package org.foxarmy.barcodescannerforemployees.views
 
 import android.app.Activity
 import android.content.Context
+import android.content.SharedPreferences
 import android.view.LayoutInflater
 import android.widget.LinearLayout
 import android.widget.TextView
 import androidx.core.content.ContextCompat
-import org.foxarmy.barcodescannerforemployees.DBStorageController
 import org.foxarmy.barcodescannerforemployees.R
 import org.foxarmy.barcodescannerforemployees.activities.MainActivity
+import org.foxarmy.barcodescannerforemployees.database.AbstractProductDAO
+import org.foxarmy.barcodescannerforemployees.database.DBStorageController
 import org.foxarmy.barcodescannerforemployees.dataclasses.Category
+import org.foxarmy.barcodescannerforemployees.getPreferences
 
 class CategoryView : LinearLayout {
     var category: Category
+
     val categoryName: TextView
     val amountOfProducts: TextView
     var isCategorySelected = false
 
+    private var abstractProductDAO: AbstractProductDAO
+    private var sharedPreferences: SharedPreferences
+
     constructor(activity: Activity, context: Context, category: Category) : super(context) {
         this.category = category
 
+        sharedPreferences = getPreferences(context)
+
+        val dbHelper = DBStorageController(context, sharedPreferences.getString("currentGroup", "database")!!)
+        abstractProductDAO = AbstractProductDAO(dbHelper)
+
         val inflater: LayoutInflater = activity.layoutInflater
         inflater.inflate(R.layout.category_view, this)
 
-        this.background = ContextCompat.getDrawable(context, if (isCategorySelected) R.drawable.outline_selected else R.drawable.outline)
+        updateStroke()
 
         categoryName = findViewById(R.id.categoryNameTextView)
         amountOfProducts = findViewById(R.id.amountOfProducts)
 
         categoryName.text = category.name
-        amountOfProducts.text = DBStorageController(context).getAmountOfAbstractProductsInCategory(DBStorageController(context).readableDatabase, category.id).toString()
+        amountOfProducts.text = abstractProductDAO.getAmountOfAbstractProductsInCategory(category.id).toString()
 
-        setOnLongClickListener {
-            isCategorySelected = !isCategorySelected
-            this.background = ContextCompat.getDrawable(context, if (isCategorySelected) R.drawable.outline_selected else R.drawable.outline)
-            true
+        setUpClicks()
+    }
+
+    private fun setUpClicks() {
+        categoryName.setOnClickListener { onCategoryClick() }
+        amountOfProducts.setOnClickListener { onCategoryClick() }
+
+        categoryName.setOnLongClickListener { onAnyLongClick() }
+        amountOfProducts.setOnLongClickListener { onAnyLongClick() }
+    }
+
+    private fun onCategoryClick(): Boolean {
+        if (context !is MainActivity) return false
+        val mainActivity = context as MainActivity
+
+        if (mainActivity.selectionMode) return onAnyLongClick()
+        else (context as MainActivity).filterAbstractProductsByCategory(category.id)
+
+        return true
+    }
+
+    private fun onAnyLongClick(): Boolean {
+        if (context !is MainActivity) return false
+        val mainActivity = context as MainActivity
+
+        isCategorySelected = !isCategorySelected
+        updateStroke()
+
+        if (mainActivity.selectionMode) {
+            if (isCategorySelected) mainActivity.addSelection()
+            else mainActivity.removeSelection()
+        } else {
+            mainActivity.addSelection()
         }
-        setOnClickListener {
-            (activity as MainActivity).filterAbstractProductsByCategory(category.id)
+        return true
+
+    }
+
+    private fun updateStroke() {
+        (context as Activity).runOnUiThread {
+            this.background = ContextCompat.getDrawable(context, if (isCategorySelected) R.drawable.outline_selected else R.drawable.outline)
         }
     }
 }

app/src/main/java/org/foxarmy/barcodescannerforemployees/views/ExpiryGroupView.kt

@@ -2,21 +2,32 @@ package org.foxarmy.barcodescannerforemployees.views
 
 import android.app.Activity
 import android.content.Context
+import android.content.SharedPreferences
 import android.view.LayoutInflater
 import android.widget.LinearLayout
 import android.widget.TextView
 import androidx.core.content.ContextCompat
-import org.foxarmy.barcodescannerforemployees.DBStorageController
 import org.foxarmy.barcodescannerforemployees.R
 import org.foxarmy.barcodescannerforemployees.activities.ExpiryCalendarActivity
+import org.foxarmy.barcodescannerforemployees.database.DBStorageController
+import org.foxarmy.barcodescannerforemployees.database.ProductDAO
+import org.foxarmy.barcodescannerforemployees.getPreferences
 import java.text.SimpleDateFormat
 
 class ExpiryGroupView : LinearLayout {
 
     private var representingDate: Long? = null
 
+    private var sharedPreferences: SharedPreferences
+    private var productDAO: ProductDAO
+
     constructor(activity: Activity, context: Context, representingDate: Long) : super(context) {
 
+        sharedPreferences = getPreferences(context)
+
+        val dbHelper = DBStorageController(context, sharedPreferences.getString("currentGroup", "database")!!)
+        productDAO = ProductDAO(dbHelper)
+
         val inflater: LayoutInflater = activity.layoutInflater
         inflater.inflate(R.layout.expiry_group_view, this)
 
@@ -24,14 +35,13 @@ class ExpiryGroupView : LinearLayout {
 
         this.background = ContextCompat.getDrawable(context,R.drawable.outline)
 
-        var amount = DBStorageController(context).findAmountOfProductsWithExpiryDate(DBStorageController(context).readableDatabase, representingDate)
+        val amount = productDAO.findAmountOfProductsWithExpiryDate(representingDate)
 
         findViewById<TextView>(R.id.representingDateTextView).text = SimpleDateFormat("dd.MM.yyyy").format(representingDate * 1000)
         findViewById<TextView>(R.id.amountTextView).text = amount.toString()
 
         setOnClickListener {
             (activity as ExpiryCalendarActivity).displayDate(representingDate)
-//            (activity as MainActivity).filterAbstractProductsByCategory(category.id)
         }
     }
 }

app/src/main/java/org/foxarmy/barcodescannerforemployees/views/GroupMemberView.kt

@@ -0,0 +1,25 @@
+package org.foxarmy.barcodescannerforemployees.views
+
+import android.app.Activity
+import android.content.Context
+import android.view.LayoutInflater
+import android.widget.LinearLayout
+import android.widget.TextView
+import org.foxarmy.barcodescannerforemployees.R
+
+class GroupMemberView : LinearLayout {
+
+    private var username: String
+    var userId: Int
+
+    constructor(activity: Activity, context: Context, username: String, userId: Int) : super(context) {
+
+        this.username = username
+        this.userId = userId
+
+        val inflater: LayoutInflater = activity.layoutInflater
+        inflater.inflate(R.layout.group_member_view, this)
+
+        findViewById<TextView>(R.id.userNameTextView).text = username
+    }
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/views/GroupView.kt

@@ -0,0 +1,37 @@
+package org.foxarmy.barcodescannerforemployees.views
+
+import android.app.Activity
+import android.content.Context
+import android.content.Intent
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.widget.LinearLayout
+import android.widget.TextView
+import androidx.core.content.ContextCompat
+import org.foxarmy.barcodescannerforemployees.R
+import org.foxarmy.barcodescannerforemployees.activities.ManageGroupActivity
+
+class GroupView : LinearLayout {
+    private var name: String
+    private var id: Int
+
+    constructor(activity: Activity, context: Context, name: String, id: Int) : super(context) {
+
+        this.name = name
+        this.id = id
+
+        val inflater: LayoutInflater = activity.layoutInflater
+        inflater.inflate(R.layout.group_view, this)
+
+        findViewById<TextView>(R.id.nameTextView).text = name
+
+        setOnClickListener {
+            val intent = Intent(activity, ManageGroupActivity::class.java)
+            val extras = Bundle()
+            extras.putInt("groupId", id)
+            intent.putExtras(extras)
+            ContextCompat.startActivity(context, intent, extras)
+        }
+    }
+
+}

app/src/main/java/org/foxarmy/barcodescannerforemployees/views/ProductView.kt

@@ -3,6 +3,7 @@ package org.foxarmy.barcodescannerforemployees.views
 import android.app.Activity
 import android.content.Context
 import android.content.Intent
+import android.content.SharedPreferences
 import android.graphics.Color
 import android.graphics.drawable.GradientDrawable
 import android.os.Build
@@ -12,6 +13,7 @@ import android.view.LayoutInflater
 import android.widget.ImageView
 import android.widget.LinearLayout
 import android.widget.TextView
+import android.widget.Toast
 import androidx.annotation.RequiresApi
 import androidx.constraintlayout.widget.ConstraintLayout
 import androidx.core.content.ContextCompat
@@ -22,6 +24,10 @@ import androidx.core.graphics.red
 import androidx.core.math.MathUtils.clamp
 import org.foxarmy.barcodescannerforemployees.*
 import org.foxarmy.barcodescannerforemployees.activities.FullscreenActivity
+import org.foxarmy.barcodescannerforemployees.activities.MainActivity
+import org.foxarmy.barcodescannerforemployees.database.AbstractProductDAO
+import org.foxarmy.barcodescannerforemployees.database.CategoryDAO
+import org.foxarmy.barcodescannerforemployees.database.DBStorageController
 import org.foxarmy.barcodescannerforemployees.dataclasses.AbstractProduct
 import org.foxarmy.barcodescannerforemployees.dataclasses.Product
 import java.io.File
@@ -30,11 +36,12 @@ import java.text.SimpleDateFormat
 import java.util.*
 import kotlin.concurrent.thread
 
-class ProductView: LinearLayout {
+class ProductView : LinearLayout {
     var product: Product = Product()
     var isProductSelected = false
-    private lateinit var activity: Activity
+    private var activity: Activity
 
+    private lateinit var productLayout: ConstraintLayout
     private lateinit var productImageView: ImageView
     private lateinit var productNameTextView: TextView
     private lateinit var productNetWeightTextView: TextView
@@ -47,8 +54,19 @@ class ProductView: LinearLayout {
     private var strokeColor: Int = 0x000000
     private lateinit var outline: GradientDrawable
 
+    private var categoryDAO: CategoryDAO
+    private var abstractProductDAO: AbstractProductDAO
+    private var sharedPreferences: SharedPreferences
+
     constructor(context: Context, a: AttributeSet) : super(context, a) {
         activity = getActivity(context)!!
+
+        sharedPreferences = getPreferences(context)
+
+        val dbHelper = DBStorageController(context, sharedPreferences.getString("currentGroup", "offline")!!)
+        abstractProductDAO = AbstractProductDAO(dbHelper)
+        categoryDAO = CategoryDAO(dbHelper)
+
         val inflater: LayoutInflater = activity.layoutInflater
         inflater.inflate(R.layout.product_view, this)
     }
@@ -60,6 +78,13 @@ class ProductView: LinearLayout {
         val inflater: LayoutInflater = activity.layoutInflater
         inflater.inflate(R.layout.product_view, this)
 
+        sharedPreferences = getPreferences(context)
+
+        val dbHelper = DBStorageController(context, sharedPreferences.getString("currentGroup", "offline")!!)
+        abstractProductDAO = AbstractProductDAO(dbHelper)
+        categoryDAO = CategoryDAO(dbHelper)
+
+        productLayout = findViewById(R.id.productLayout)
         productImageView = findViewById(R.id.productPicture)
         productNameTextView = findViewById(R.id.productNameView)
         productNetWeightTextView = findViewById(R.id.productNetWeightView)
@@ -68,72 +93,152 @@ class ProductView: LinearLayout {
         productLifeSpan = findViewById(R.id.dateSpan)
         productFreshnessTextView = findViewById(R.id.freshnessPercentTextView)
 
-        findViewById<ConstraintLayout>(R.id.productLayout).setOnLongClickListener {
-            isProductSelected = !isProductSelected
-            updateStroke()
-            true
-        }
-
-        productImageView.setOnClickListener {
-            val fullscreenIntent = Intent(activity, FullscreenActivity::class.java)
-            val extras = Bundle()
-            val abstractProduct = DBStorageController(context).findAbstractProductById(DBStorageController(context).readableDatabase, product.abstractProductId)
-            extras.putString("imagehash", abstractProduct!!.imageHash)
-            fullscreenIntent.putExtras(extras)
-            startActivity(context, fullscreenIntent, extras)
-        }
+        setUpClicks()
 
         update()
     }
 
     @RequiresApi(Build.VERSION_CODES.O)
-    fun update () {
-        val linkedAbstractProduct: AbstractProduct? = DBStorageController(activity).findAbstractProductById(DBStorageController(activity).readableDatabase, product.abstractProductId)
+    private fun setUpClicks() {
+        productLayout.setOnLongClickListener { onAnyLongClick() }
+        productImageView.setOnLongClickListener { onImageLongClick() }
+        productNameTextView.setOnLongClickListener { onNameLongClick() }
+        productNetWeightTextView.setOnLongClickListener { onAnyLongClick() }
+        productAmountTextView.setOnLongClickListener { onAnyLongClick() }
+        productCategoryView.setOnLongClickListener { onAnyLongClick() }
+        productLifeSpan.setOnLongClickListener { onAnyLongClick() }
+        productFreshnessTextView.setOnLongClickListener { onAnyLongClick() }
 
-        if(linkedAbstractProduct == null) {
-            return
+        productLayout.setOnClickListener { onAnyClick() }
+        productImageView.setOnClickListener { onImageLongClick() }
+        productNameTextView.setOnClickListener { onNameLongClick() }
+        productNetWeightTextView.setOnClickListener { onAnyClick() }
+        productAmountTextView.setOnClickListener { onAnyClick() }
+        productCategoryView.setOnClickListener { onAnyClick() }
+        productLifeSpan.setOnClickListener { onAnyClick() }
+        productFreshnessTextView.setOnClickListener { onAnyClick() }
+    }
+
+    @RequiresApi(Build.VERSION_CODES.O)
+    private fun onAnyClick(): Boolean {
+        if (activity !is MainActivity) return false
+        val mainActivity = activity as MainActivity
+
+        if (mainActivity.selectionMode) {
+            isProductSelected = !isProductSelected
+
+            if (isProductSelected) mainActivity.addSelection()
+            else mainActivity.removeSelection()
+
+            updateStroke()
+
+            return true
+        } else {
+            return false
         }
+    }
+
+    @RequiresApi(Build.VERSION_CODES.O)
+    private fun onAnyLongClick(): Boolean {
+        if (activity !is MainActivity) return false
+        val mainActivity = activity as MainActivity
+
+        isProductSelected = !isProductSelected
+        updateStroke()
+
+        if (mainActivity.selectionMode) {
+            if (isProductSelected) mainActivity.addSelection()
+            else mainActivity.removeSelection()
+        } else {
+            mainActivity.addSelection()
+        }
+        return true
+
+    }
+
+    private fun onNameLongClick(): Boolean {
+        if (activity !is MainActivity) {
+            Toast.makeText(activity, productNameTextView.text, Toast.LENGTH_SHORT).show()
+            return true
+        }
+        val mainActivity = activity as MainActivity
+
+        if (mainActivity.selectionMode) return onAnyLongClick()
+        else Toast.makeText(activity, productNameTextView.text, Toast.LENGTH_SHORT).show()
+        return true
+    }
+
+    private fun onImageLongClick(): Boolean {
+        val abstractProduct = abstractProductDAO.findAbstractProductById(product.abstractProductId)
+
+        if (activity !is MainActivity) {
+            val fullscreenIntent = Intent(activity, FullscreenActivity::class.java)
+            val extras = Bundle()
+            extras.putString("imagehash", abstractProduct!!.imageHash)
+            fullscreenIntent.putExtras(extras)
+            startActivity(context, fullscreenIntent, extras)
+            return true
+        }
+        val mainActivity = activity as MainActivity
+
+        if (mainActivity.selectionMode) {
+            return onAnyLongClick()
+        } else {
+            val fullscreenIntent = Intent(activity, FullscreenActivity::class.java)
+            val extras = Bundle()
+            extras.putString("imagehash", abstractProduct!!.imageHash)
+            fullscreenIntent.putExtras(extras)
+            startActivity(context, fullscreenIntent, extras)
+        }
+        return true
+    }
+
+    @RequiresApi(Build.VERSION_CODES.O)
+    fun update() {
+        val linkedAbstractProduct: AbstractProduct =
+            abstractProductDAO.findAbstractProductById(product.abstractProductId) ?: return
 
         val thumbnailsDir = File(activity.cacheDir, "thumbnails")
         thumbnailsDir.mkdirs()
         val pictureFile = File(thumbnailsDir, "${linkedAbstractProduct.imageHash}.webp")
         val imageUri = getImageUri(activity, pictureFile)
         productImageView.setImageURI(imageUri)
-//        productImageView.rotation = 90f
 
         productNameTextView.text = linkedAbstractProduct.name
         productNetWeightTextView.text = linkedAbstractProduct.netWeight.toString()
         productAmountTextView.text = product.amount.toString()
-        productCategoryView.text = DBStorageController(activity).getCategoryNameById(DBStorageController(activity).readableDatabase, linkedAbstractProduct.category)
-        productLifeSpan.text = "${SimpleDateFormat("dd.MM.yyyy").format(Date(product.dateOfProduction*1000))}-${SimpleDateFormat("dd.MM.yyyy").format(Date(product.dateOfExpiry*1000))}"
+        productCategoryView.text = categoryDAO.getCategoryNameById(linkedAbstractProduct.category)
+        productLifeSpan.text = "${SimpleDateFormat("dd.MM.yyyy").format(Date(product.dateOfProduction * 1000))}-${
+            SimpleDateFormat("dd.MM.yyyy").format(Date(product.dateOfExpiry * 1000))
+        }"
         productFreshnessTextView.text =
-        if (product.freshness == Double.NEGATIVE_INFINITY || product.freshness == Double.POSITIVE_INFINITY || product.freshness < 0) {
-            context.getString(R.string.expired)
-        } else {
-            "${DecimalFormat("#.#").format(product.freshness*100)}%"
-        }
+            if (product.freshness == Double.NEGATIVE_INFINITY || product.freshness == Double.POSITIVE_INFINITY || product.freshness < 0) {
+                context.getString(R.string.expired)
+            } else {
+                "${DecimalFormat("#.#").format(product.freshness * 100)}%"
+            }
 
         updateStroke()
     }
 
     @RequiresApi(Build.VERSION_CODES.O)
     fun updateStroke() {
-         if (isProductSelected) {
-             this.background = ContextCompat.getDrawable(context, R.drawable.outline_selected)
-        } else {
-             if (product.id != 0) {
-                 thread {
-                     this.outline = GradientDrawable()
-                     backgroundColor = evaluateColor()
-                     strokeColor = darkenColor(backgroundColor, 0.25) // (backgroundColor and 0xfefefe ) shr 1
-                     this.outline.setColor(backgroundColor)
-                     this.outline.setStroke(4, strokeColor)
-                     this.outline.alpha = 84
-                     this.background = outline
-                 }
-             } else {
-                 this.background = ContextCompat.getDrawable(context, R.drawable.outline)
-             }
+        activity.runOnUiThread {
+            if (isProductSelected) {
+                this.background = ContextCompat.getDrawable(context, R.drawable.outline_selected)
+            } else {
+                if (product.id != 0) {
+                        this.outline = GradientDrawable()
+                        backgroundColor = evaluateColor()
+                        strokeColor = darkenColor(backgroundColor, 0.25) // (backgroundColor and 0xfefefe ) shr 1
+                        this.outline.setColor(backgroundColor)
+                        this.outline.setStroke(4, strokeColor)
+                        this.outline.alpha = 84
+                        this.background = outline
+                } else {
+                    this.background = ContextCompat.getDrawable(context, R.drawable.outline)
+                }
+            }
         }
     }
 
@@ -144,13 +249,15 @@ class ProductView: LinearLayout {
     }
 
     fun calculateFreshnessGradient(percentage: Double): Int {
-        val startColor = ContextCompat.getColor(context, if (percentage > 0.5) R.color.full_freshness else R.color.half_freshness)
-        val endColor = ContextCompat.getColor(context, if (percentage > 0.5) R.color.half_freshness else R.color.expired_freshness)
+        val startColor =
+            ContextCompat.getColor(context, if (percentage > 0.5) R.color.full_freshness else R.color.half_freshness)
+        val endColor =
+            ContextCompat.getColor(context, if (percentage > 0.5) R.color.half_freshness else R.color.expired_freshness)
 
         val gradientPosition = 1 - if (percentage > 0.5) (percentage - 0.5) * 2 else percentage * 2
 
-        val red = clamp((startColor.red + gradientPosition * (endColor.red - startColor.red )).toInt(), 0, 255)
-        val green = clamp((startColor.green  + gradientPosition * (endColor.green - startColor.green)).toInt(), 0, 255)
+        val red = clamp((startColor.red + gradientPosition * (endColor.red - startColor.red)).toInt(), 0, 255)
+        val green = clamp((startColor.green + gradientPosition * (endColor.green - startColor.green)).toInt(), 0, 255)
         val blue = clamp((startColor.blue + gradientPosition * (endColor.blue - startColor.blue)).toInt(), 0, 255)
 
         var redHex = Integer.toHexString(red)
@@ -160,7 +267,7 @@ class ProductView: LinearLayout {
         if (greenHex.length == 1) greenHex = "0$greenHex"
 
         var blueHex = Integer.toHexString(blue)
-        if (blueHex.length == 1 ) blueHex = "0$blueHex"
+        if (blueHex.length == 1) blueHex = "0$blueHex"
 
 
         val colorString = "#$redHex$greenHex$blueHex"
@@ -168,7 +275,7 @@ class ProductView: LinearLayout {
     }
 
     @RequiresApi(Build.VERSION_CODES.O)
-    fun darkenColor(color: Int, darkPercent: Double) : Int {
+    fun darkenColor(color: Int, darkPercent: Double): Int {
         val c = Color.valueOf(color)
 
         val red = c.red() * (1 - darkPercent)

app/src/main/res/drawable/seekbar_tick.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape xmlns:android="http://schemas.android.com/apk/res/android"
+       android:shape="oval">
+    <size android:width="4dp" android:height="4dp" />
+    <solid android:color="#FFFFFF" />
+</shape>

app/src/main/res/layout/abstract_product_view.xml

@@ -8,7 +8,7 @@
     <androidx.constraintlayout.widget.ConstraintLayout
             android:layout_width="match_parent"
             android:layout_height="match_parent" android:id="@+id/productLayout" android:outlineProvider="bounds"
-            android:background="#00FFFEFE" android:clickable="true">
+            android:background="#00FFFEFE" android:clickable="true" android:translationZ="0sp">
         <ImageView
                 android:layout_width="match_parent"
                 android:layout_height="200dp" app:srcCompat="@android:drawable/ic_menu_gallery"

app/src/main/res/layout/activity_account_settings.xml

@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+                                                   xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
+                                                   android:layout_height="match_parent">
+
+    <EditText
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:inputType="textPassword"
+            android:ems="10"
+            android:id="@+id/newPasswordTextEdit"
+            app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintHorizontal_bias="0.497" android:hint="@string/new_password"
+            app:layout_constraintTop_toBottomOf="@+id/saveUsernameButton" android:layout_marginTop="64dp"/>
+    <EditText
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:inputType="text"
+            android:ems="10"
+            android:id="@+id/newUsernameTextEdit"
+            app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent"
+            android:hint="@string/new_name" app:layout_constraintTop_toTopOf="parent" android:layout_marginTop="48dp"/>
+    <Button
+            android:text="@string/saveButton"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content" android:id="@+id/saveUsernameButton"
+            app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@+id/newUsernameTextEdit" android:layout_marginTop="16dp"/>
+    <Button
+            android:text="@string/saveButton"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content" android:id="@+id/savePasswordButton"
+            app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent"
+            android:layout_marginTop="16dp" app:layout_constraintTop_toBottomOf="@+id/newPasswordTextEdit"/>
+</androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/layout/activity_find_barcodeless_abstract_product.xml

@@ -1,10 +1,15 @@
 <?xml version="1.0" encoding="utf-8"?>
-<androidx.core.widget.NestedScrollView
+<androidx.constraintlayout.widget.ConstraintLayout
         xmlns:android="http://schemas.android.com/apk/res/android"
-        xmlns:tools="http://schemas.android.com/tools"
-        android:layout_width="match_parent"
-        android:layout_height="match_parent"
-        tools:context=".fragments.ShelfFragment"
-        android:id="@+id/content">
+        xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools"
+        android:layout_width="match_parent" android:layout_height="match_parent">
 
-</androidx.core.widget.NestedScrollView>
+    <androidx.core.widget.NestedScrollView
+            android:layout_height="0dp"
+            tools:context=".fragments.ShelfFragment"
+            android:id="@+id/content" android:layout_width="0dp" app:layout_constraintTop_toTopOf="parent"
+            app:layout_constraintStart_toStartOf="parent" app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent">
+
+    </androidx.core.widget.NestedScrollView>
+</androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/layout/activity_group.xml

@@ -0,0 +1,38 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+                                                   xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
+                                                   android:layout_height="match_parent">
+    <EditText
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:inputType="text"
+            android:ems="10"
+            android:id="@+id/groupNameTextEdit"
+            app:layout_constraintStart_toStartOf="parent" app:layout_constraintEnd_toEndOf="parent"
+            android:hint="@string/group_name" app:layout_constraintTop_toTopOf="parent"
+            android:layout_marginTop="210dp"/>
+    <EditText
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:inputType="textPassword"
+            android:ems="10"
+            android:id="@+id/groupPasswordTextEdit"
+            android:layout_marginTop="27dp"
+            app:layout_constraintTop_toBottomOf="@+id/groupNameTextEdit" android:hint="@string/group_password"
+            app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent"/>
+    <Button
+            android:text="@string/create_group"
+            android:layout_width="91dp"
+            android:layout_height="wrap_content" android:id="@+id/createGroupButton"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@+id/groupPasswordTextEdit"
+            android:layout_marginTop="24dp" app:layout_constraintEnd_toStartOf="@+id/joinGroupButton"
+            android:layout_marginEnd="12dp"/>
+    <Button
+            android:text="@string/join_group"
+            android:layout_width="91dp"
+            android:layout_height="wrap_content" android:id="@+id/joinGroupButton"
+            app:layout_constraintEnd_toEndOf="parent" app:layout_constraintTop_toBottomOf="@+id/groupPasswordTextEdit"
+            android:layout_marginTop="24dp" android:layout_marginStart="12dp"
+            app:layout_constraintStart_toEndOf="@+id/createGroupButton"/>
+</androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/layout/activity_login.xml

@@ -0,0 +1,62 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+                                                   xmlns:app="http://schemas.android.com/apk/res-auto"
+                                                   xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
+                                                   android:layout_height="match_parent">
+
+    <Button
+            android:text="@string/register"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content" android:id="@+id/registerButton"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintEnd_toStartOf="@+id/loginButton" app:layout_constraintHorizontal_bias="0.15"
+            app:layout_constraintBottom_toTopOf="@+id/offlineButton" android:layout_marginBottom="64dp"/>
+    <Button
+            android:text="@string/login"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content" android:id="@+id/loginButton"
+            app:layout_constraintStart_toEndOf="@+id/registerButton" app:layout_constraintEnd_toEndOf="parent"
+            android:layout_marginStart="2dp"
+            app:layout_constraintHorizontal_bias="0.1" app:layout_constraintBottom_toTopOf="@+id/offlineButton"
+            android:layout_marginBottom="64dp"/>
+    <Button
+            android:text="@string/offline"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content" android:id="@+id/offlineButton"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintEnd_toEndOf="parent" app:layout_constraintBottom_toBottomOf="parent"
+            android:layout_marginBottom="250dp"/>
+    <EditText
+            android:layout_width="wrap_content"
+            android:layout_height="50dp"
+            android:inputType="text"
+            android:ems="10"
+            android:id="@+id/usernameTextEdit"
+            app:layout_constraintStart_toStartOf="parent" app:layout_constraintEnd_toEndOf="parent"
+            android:hint="@string/username" app:layout_constraintBottom_toTopOf="@+id/passwordTextEdit"
+            android:layout_marginBottom="16dp"/>
+    <EditText
+            android:layout_width="wrap_content"
+            android:layout_height="50dp"
+            android:inputType="textPassword"
+            android:ems="10"
+            android:id="@+id/passwordTextEdit"
+            android:hint="@string/password" app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintBottom_toTopOf="@+id/languageSpinner" android:layout_marginBottom="24dp"/>
+    <EditText
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:inputType="text"
+            android:ems="10"
+            android:id="@+id/serverTextEdit"
+            app:layout_constraintStart_toStartOf="parent" app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintBottom_toTopOf="@+id/usernameTextEdit" android:layout_marginBottom="16dp"
+            android:hint="@string/server" android:text="bsfe.foxarmy.org"/>
+    <Spinner
+            android:layout_width="409dp"
+            android:layout_height="32dp" android:id="@+id/languageSpinner"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintBottom_toTopOf="@+id/registerButton" android:layout_marginBottom="24dp"/>
+</androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/layout/activity_main.xml

@@ -1,61 +1,75 @@
 <?xml version="1.0" encoding="utf-8"?>
-<androidx.coordinatorlayout.widget.CoordinatorLayout
+<androidx.drawerlayout.widget.DrawerLayout
         xmlns:android="http://schemas.android.com/apk/res/android"
         xmlns:app="http://schemas.android.com/apk/res-auto"
         xmlns:tools="http://schemas.android.com/tools"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
-        android:fitsSystemWindows="true"
-        tools:context=".activities.MainActivity">
+        tools:context=".activities.MainActivity"
+        android:fitsSystemWindows="true" android:id="@+id/drawer_layout">
 
-    <androidx.constraintlayout.widget.ConstraintLayout
+    <FrameLayout
             android:layout_width="match_parent"
-            android:layout_height="match_parent" android:id="@+id/storageLayout">
+            android:layout_height="match_parent">
 
-    </androidx.constraintlayout.widget.ConstraintLayout>
-    <com.google.android.material.appbar.AppBarLayout
-            android:layout_height="wrap_content"
-            android:layout_width="match_parent"
-            android:fitsSystemWindows="true"
-    >
-
-        <com.google.android.material.appbar.MaterialToolbar
-                android:id="@+id/toolbar"
+        <androidx.constraintlayout.widget.ConstraintLayout
                 android:layout_width="match_parent"
-                android:layout_height="?attr/actionBarSize"/>
+                android:layout_height="match_parent" android:id="@+id/storageLayout">
 
-        <com.google.android.material.tabs.TabLayout
-                android:id="@+id/tab_tablayout"
-                android:layout_width="match_parent"
-                android:layout_height="wrap_content"
-                app:tabIndicatorColor="#FFF"
-                app:tabIndicatorHeight="3dp"
-                app:tabMode="fixed" />
+            <com.google.android.material.appbar.AppBarLayout
+                    android:layout_height="wrap_content"
+                    android:layout_width="match_parent"
+                    android:fitsSystemWindows="true"
+                    android:id="@+id/appBarLayout">
 
-    </com.google.android.material.appbar.AppBarLayout>
+                <com.google.android.material.appbar.MaterialToolbar
+                        android:id="@+id/toolbar"
+                        android:layout_width="match_parent"
+                        android:layout_height="?attr/actionBarSize"/>
 
-<!--    <include layout="@layout/content_storage"/>-->
-    <androidx.viewpager.widget.ViewPager
-            android:id="@+id/tab_viewpager"
-            android:layout_width="match_parent"
+                <com.google.android.material.tabs.TabLayout
+                        android:id="@+id/tab_tablayout"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        app:tabIndicatorColor="#FFF"
+                        app:tabIndicatorHeight="3dp"
+                        app:tabMode="fixed"/>
+
+            </com.google.android.material.appbar.AppBarLayout>
+            <androidx.viewpager.widget.ViewPager
+                    android:id="@+id/tab_viewpager"
+                    android:layout_width="0dp"
+                    android:layout_height="0dp"
+                    app:layout_behavior="@string/appbar_scrolling_view_behavior" android:layout_gravity="bottom"
+                    android:layout_marginTop="2dp"
+                    app:layout_constraintTop_toBottomOf="@+id/appBarLayout"
+                    app:layout_constraintStart_toStartOf="parent" android:layout_marginStart="6dp"
+                    app:layout_constraintEnd_toEndOf="parent" android:layout_marginEnd="6dp"
+                    app:layout_constraintBottom_toBottomOf="parent"/>
+            <com.google.android.material.floatingactionbutton.FloatingActionButton
+                    android:id="@+id/new_element_fab"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_gravity="bottom|end"
+                    app:srcCompat="@android:drawable/ic_input_add"
+                    app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent"
+                    android:layout_marginEnd="16dp" android:layout_marginBottom="16dp"/>
+            <com.google.android.material.floatingactionbutton.FloatingActionButton
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:clickable="true" app:srcCompat="@android:drawable/ic_menu_my_calendar"
+                    android:id="@+id/expiryCalendarFab" android:layout_gravity="bottom|end"
+                    app:layout_constraintBottom_toTopOf="@+id/new_element_fab" android:layout_marginBottom="16dp"
+                    app:layout_constraintEnd_toEndOf="parent" android:layout_marginEnd="16dp"/>
+        </androidx.constraintlayout.widget.ConstraintLayout>
+    </FrameLayout>
+
+    <!--    <include layout="@layout/content_storage"/>-->
+
+    <com.google.android.material.navigation.NavigationView
+            android:layout_width="wrap_content"
             android:layout_height="match_parent"
-            android:layout_marginTop="5dp"
-            app:layout_behavior="@string/appbar_scrolling_view_behavior" />
+            android:layout_gravity="start"
+            app:menu="@menu/drawer_menu" android:id="@+id/nav_view"/>
 
-    <com.google.android.material.floatingactionbutton.FloatingActionButton
-            android:id="@+id/new_element_fab"
-            android:layout_width="wrap_content"
-            android:layout_height="wrap_content"
-            android:layout_gravity="bottom|end"
-            android:layout_marginEnd="@dimen/fab_margin"
-            android:layout_marginBottom="16dp"
-            app:srcCompat="@android:drawable/ic_input_add"/>
-    <com.google.android.material.floatingactionbutton.FloatingActionButton
-            android:layout_width="wrap_content"
-            android:layout_height="wrap_content"
-            android:clickable="true" app:srcCompat="@android:drawable/ic_menu_my_calendar"
-            android:id="@+id/expiryCalendarFab" android:layout_gravity="bottom|end"
-            tools:layout_editor_absoluteY="742dp" tools:layout_editor_absoluteX="337dp"
-            android:layout_marginBottom="84dp" android:layout_marginRight="16dp"/>
-
-</androidx.coordinatorlayout.widget.CoordinatorLayout>
+</androidx.drawerlayout.widget.DrawerLayout>

app/src/main/res/layout/activity_manage_group.xml

@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+                                                   xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
+                                                   android:layout_height="match_parent">
+
+    <Button
+            android:text="@string/leave_group"
+            android:layout_width="91dp"
+            android:layout_height="wrap_content" android:id="@+id/leaveButton"
+            app:layout_constraintStart_toStartOf="parent" android:layout_marginStart="12dp"
+            app:layout_constraintTop_toTopOf="parent" android:layout_marginTop="48dp"
+            app:layout_constraintEnd_toStartOf="@+id/renameButton" android:layout_marginEnd="12dp"/>
+    <Button
+            android:text="@string/rename_group"
+            android:layout_width="91dp"
+            android:layout_height="wrap_content" android:id="@+id/renameButton"
+            app:layout_constraintTop_toTopOf="parent"
+            android:layout_marginTop="48dp"
+            app:layout_constraintStart_toEndOf="@+id/leaveButton" app:layout_constraintEnd_toStartOf="@+id/button3"
+            android:visibility="visible"/>
+    <Button
+            android:text="Button"
+            android:layout_width="91dp"
+            android:layout_height="wrap_content" android:id="@+id/button3"
+            app:layout_constraintTop_toTopOf="parent"
+            android:layout_marginTop="48dp"
+            app:layout_constraintEnd_toEndOf="parent" android:layout_marginEnd="12dp"
+            app:layout_constraintStart_toEndOf="@+id/renameButton" android:visibility="gone"
+            android:layout_marginStart="12dp"/>
+    <ScrollView
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content" app:layout_constraintTop_toBottomOf="@+id/leaveButton"
+            android:layout_marginTop="48dp" android:id="@+id/membersScrollView">
+        <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content"
+                      android:orientation="vertical" android:id="@+id/groupsContent"/>
+    </ScrollView>
+</androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/layout/activity_my_groups.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+                                                   xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
+                                                   android:layout_height="match_parent">
+
+    <Button
+            android:text="@string/join_or_create_group"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content" android:id="@+id/newGroup"
+            app:layout_constraintStart_toStartOf="parent" app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintTop_toTopOf="parent" android:layout_marginTop="24dp"/>
+    <ScrollView
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content" android:id="@+id/groupsContent"
+            app:layout_constraintTop_toBottomOf="@+id/newGroup" android:layout_marginTop="16dp">
+        <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content"
+                      android:orientation="vertical" android:id="@+id/groupsLayout"/>
+    </ScrollView>
+</androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/layout/activity_settings.xml

@@ -0,0 +1,58 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+                                                   xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
+                                                   android:layout_height="match_parent">
+
+    <LinearLayout
+            android:orientation="horizontal"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content" app:layout_constraintTop_toTopOf="parent"
+            app:layout_constraintStart_toStartOf="parent" android:id="@+id/imageCompressionSetting"
+            android:layout_marginTop="16dp">
+        <TextView
+                android:text="@string/image_compress_factor"
+                android:layout_width="187dp"
+                android:layout_height="30dp" android:id="@+id/imageCompressionFactorTextView" android:textSize="20sp"
+                android:textAlignment="center"
+        />
+        <SeekBar
+                style="@style/Widget.AppCompat.SeekBar.Discrete"
+                android:layout_width="219dp"
+                android:layout_height="wrap_content"
+                android:max="15"
+                android:progress="0"
+                android:id="@+id/imageCompressionFactorSeekBar"
+                android:tickMark="@drawable/seekbar_tick"
+                android:tickMarkTint="@color/seekbar_tick_color"
+                android:layout_marginTop="6dp" android:indeterminateOnly="false" android:splitTrack="true"/>
+
+    </LinearLayout>
+    <LinearLayout
+            android:orientation="horizontal"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content" android:id="@+id/currentGroupSetting"
+            app:layout_constraintTop_toBottomOf="@+id/imageCompressionSetting">
+        <TextView
+                android:text="@string/current_group"
+                android:layout_width="81dp"
+                android:layout_height="wrap_content" android:id="@+id/currentGroupTextView" android:layout_weight="1"
+                android:textSize="20sp" android:textAlignment="center"/>
+        <Spinner
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content" android:id="@+id/currentGroupSpinner" android:layout_weight="1"
+                android:layout_marginTop="-1dp"/>
+    </LinearLayout>
+    <Button
+            android:text="@string/saveButton"
+            android:layout_width="88dp"
+            android:layout_height="wrap_content" android:id="@+id/saveButton"
+            app:layout_constraintTop_toBottomOf="@+id/currentGroupSetting"
+            app:layout_constraintStart_toStartOf="parent" app:layout_constraintEnd_toStartOf="@+id/cancelButton"
+            android:layout_marginTop="32dp"/>
+    <Button
+            android:text="@string/cancel"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content" android:id="@+id/cancelButton"
+            app:layout_constraintTop_toBottomOf="@+id/currentGroupSetting" app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toEndOf="@+id/saveButton" android:layout_marginTop="32dp"/>
+</androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/layout/content_storage.xml

@@ -1,20 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<androidx.constraintlayout.widget.ConstraintLayout
-        xmlns:android="http://schemas.android.com/apk/res/android"
-        xmlns:app="http://schemas.android.com/apk/res-auto"
-        android:layout_width="match_parent"
-        android:layout_height="match_parent"
-        app:layout_behavior="@string/appbar_scrolling_view_behavior" android:id="@+id/storageLayout">
-
-    <fragment
-            android:id="@+id/nav_host_fragment_content_storage"
-            android:name="androidx.navigation.fragment.NavHostFragment"
-            android:layout_width="0dp"
-            android:layout_height="0dp"
-            app:layout_constraintStart_toStartOf="parent"
-            app:layout_constraintEnd_toEndOf="parent"
-            app:layout_constraintTop_toTopOf="parent"
-            app:layout_constraintBottom_toBottomOf="parent"
-            app:defaultNavHost="true"
-            app:navGraph="@navigation/nav_graph_main"/>
-</androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/layout/fragment_add_abstract_product.xml

@@ -62,7 +62,7 @@
                 android:ems="10"
                 android:id="@+id/barcodeTextEdit" app:layout_constraintTop_toBottomOf="@+id/imageView"
                 app:layout_constraintStart_toStartOf="parent"
-                android:layout_marginTop="8dp" android:hint="Barcode" android:textColorHint="#737373"
+                android:layout_marginTop="8dp" android:hint="@string/barcode" android:textColorHint="#737373"
                 android:layout_marginStart="5dp"/>
         <CheckBox
                 android:text="@string/no_barcode"

app/src/main/res/layout/fragment_shelf.xml

@@ -2,7 +2,7 @@
 <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
              xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent"
              android:layout_height="match_parent"
-             android:background="#141218">
+>
 
     <androidx.constraintlayout.widget.ConstraintLayout
             android:layout_width="match_parent"
@@ -26,7 +26,8 @@
                 android:layout_width="match_parent"
                 android:layout_height="match_parent" app:layout_constraintTop_toBottomOf="@+id/spinner"
                 android:layout_marginTop="32dp" app:layout_constraintStart_toStartOf="parent"
-                app:layout_constraintEnd_toEndOf="parent" android:id="@+id/scrollView">
+                app:layout_constraintEnd_toEndOf="parent" android:id="@+id/scrollView"
+                app:layout_constraintBottom_toBottomOf="parent">
             <androidx.gridlayout.widget.GridLayout
                     android:layout_width="match_parent"
                     android:layout_height="wrap_content" android:id="@+id/contentGridLayout" app:columnCount="2"

app/src/main/res/layout/fragment_storage.xml

@@ -1,13 +1,9 @@
 <?xml version="1.0" encoding="utf-8"?>
-<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
-             xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools"
-             android:layout_width="match_parent"
-             android:layout_height="match_parent"
-             android:id="@+id/fragment_storage"
-             tools:context=".fragments.StorageFragment">
-    <androidx.constraintlayout.widget.ConstraintLayout
-            android:layout_width="match_parent"
-            android:layout_height="match_parent">
+
+<androidx.constraintlayout.widget.ConstraintLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto">
 
         <TextView
                 android:text="@string/sort_by"
@@ -16,7 +12,7 @@
                 app:layout_constraintStart_toStartOf="parent"
                 app:layout_constraintTop_toTopOf="parent"
                 android:textAlignment="center"
-                app:layout_constraintBottom_toBottomOf="@+id/scrollView2"/>
+                app:layout_constraintBottom_toTopOf="@+id/scrollView2"/>
         <Spinner
                 android:layout_width="0dp"
                 android:layout_height="32dp" android:id="@+id/spinner"
@@ -34,15 +30,16 @@
                 android:layout_marginEnd="10dp" app:layout_constraintTop_toTopOf="parent"/>
         <ScrollView
                 android:layout_width="match_parent"
-                android:layout_height="wrap_content"
+                android:layout_height="0dp"
                 android:id="@+id/scrollView2"
-                app:layout_constraintTop_toBottomOf="@+id/dropFiltersButton">
+                app:layout_constraintTop_toBottomOf="@+id/dropFiltersButton"
+                android:layout_marginTop="4dp" app:layout_constraintStart_toStartOf="parent"
+                app:layout_constraintEnd_toEndOf="parent">
             <androidx.gridlayout.widget.GridLayout
                     android:layout_width="match_parent"
-                    android:layout_height="wrap_content" android:id="@+id/contentGridLayout" app:columnCount="2"
+                    android:layout_height="match_parent" android:id="@+id/contentGridLayout" app:columnCount="2"
                     app:rowCount="100" android:nestedScrollingEnabled="true">
 
             </androidx.gridlayout.widget.GridLayout>
         </ScrollView>
     </androidx.constraintlayout.widget.ConstraintLayout>
-</FrameLayout>

app/src/main/res/layout/group_member_view.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+              android:orientation="horizontal"
+              android:layout_width="match_parent"
+              android:layout_height="match_parent">
+
+    <TextView
+            android:text="User"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content" android:id="@+id/userNameTextView" android:layout_weight="1"
+            android:textSize="30sp"/>
+</LinearLayout>

app/src/main/res/layout/group_view.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+              android:orientation="vertical"
+              android:layout_width="match_parent"
+              android:layout_height="match_parent">
+
+    <TextView
+            android:text="Group"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content" android:id="@+id/nameTextView" android:textSize="30sp"/>
+</LinearLayout>

app/src/main/res/menu/drawer_menu.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+      xmlns:tools="http://schemas.android.com/tools">
+
+    <item
+            android:id="@+id/nav_account"
+            android:title="@string/my_account" />
+
+    <item
+            android:id="@+id/nav_groups"
+            android:title="@string/my_groups" />
+    <item
+            android:id="@+id/nav_settings"
+            android:title="@string/settings"/>
+    <item android:title="@string/logout" android:id="@+id/nav_logout"/>
+</menu>

app/src/main/res/menu/menu_main.xml

@@ -3,7 +3,7 @@
       xmlns:tools="http://schemas.android.com/tools"
       tools:context="org.foxarmy.barcodescannerforemployees.activities.MainActivity">
     <item android:id="@+id/action_settings"
-          android:title="@string/action_settings"
+          android:title="@string/settings"
           android:orderInCategory="100"
           app:showAsAction="never"/>
     <item android:id="@+id/action_delete" android:title="@string/delete_menu"/>

app/src/main/res/menu/user_pop_menu.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <item android:title="@string/kick" android:id="@+id/kick"/>
+    <item android:title="@string/transfer_ownership" android:id="@+id/transfer_ownership"/>
+</menu>

app/src/main/res/values-ru/strings.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
     <string name="app_name">СканнерШтрихкодовДляРаботников</string>
-    <string name="action_settings">Настройки</string>
+    <string name="settings">Настройки</string>
     <string name="first_fragment_label">Добавить продукт</string>
     <string name="second_fragment_label">Продукты</string>
     <string name="scan_label">Сканировать</string>
@@ -87,6 +87,47 @@
         ошибка сканирования или введите данные вручную
     </string>
     <string name="abstract_product_request">Пожалуйста, отсканируйте штрихкод, чтобы добавить продукт</string>
-    <string name="no_barcode">No barcode present</string>
-    <string name="no_barcode_button">No barcode</string>
+    <string name="no_barcode">Нет штрихкода</string>
+    <string name="no_barcode_button">Без штрихкода</string>
+    <string name="register">Зарегистрироваться</string>
+    <string name="login">Войти</string>
+    <string name="offline">Оффлайн</string>
+    <string name="username">Имя пользователя</string>
+    <string name="password">Пароль</string>
+    <string name="username_already_exists">Имя пользователя занято</string>
+    <string name="wrong_password">Неправильный пароль</string>
+    <string name="server">Сервер</string>
+    <string name="my_account">Мой аккаунт</string>
+    <string name="my_groups">Мои группы</string>
+    <string name="nav_open">Открыть навигатор</string>
+    <string name="nav_close">Закрыть навигатор</string>
+    <string name="new_name">Новое имя</string>
+    <string name="new_password">Новый пароль</string>
+    <string name="group_name">Имя группы</string>
+    <string name="group_password">Пароль группы</string>
+    <string name="create_group">Создать группу</string>
+    <string name="join_group">Присоединиться к группе</string>
+    <string name="leave">Выйти</string>
+    <string name="leave_group">Покинуть группу</string>
+    <string name="rename_group">Переименовать группу</string>
+    <string name="join_or_create_group">Присоединиться или создать группу</string>
+    <string name="image_compress_factor">Степень сжатия изображения</string>
+    <string name="current_group">Текущая группа</string>
+    <string name="cancel">Отмена</string>
+    <string name="no_internet_connection">Не могу установить соединение с сервером. Возможно, вы отключены от сети?</string>
+    <string name="ok">Ок</string>
+    <string name="logout">Выйти</string>
+    <string name="online_only_feature">Эта возможность доступна только с онлайн аккаунтом</string>
+    <string name="username_changed">Имя пользователя изменено. Пожалуйста, перезайдите</string>
+    <string name="password_changed">Пароль изменён. Пожалуйста, перезайдите</string>
+    <string name="new_group_name">Введите новое имя группы</string>
+    <string name="kick">Выгнать</string>
+    <string name="transfer_ownership">Передать владение группой</string>
+    <string name="transfer_ownership_confirmation">Вы увереных, что хотите передать владение группой этому пользователю?</string>
+    <string name="loading_please_wait">Загрузка, пожалуйста ждите</string>
+    <string name="loading">Загрузка</string>
+    <string-array name="languages">
+        <item>en-US</item>
+        <item>ru-RU</item>
+    </string-array>
 </resources>

app/src/main/res/values/colors.xml

@@ -14,4 +14,5 @@
     <color name="full_freshness">#5AFF30</color>
     <color name="half_freshness">#FFF200</color>
     <color name="expired_freshness">#ff0000</color>
+    <color name="seekbar_tick_color">#FFFFFF</color>
 </resources>

app/src/main/res/values/strings.xml

@@ -1,6 +1,6 @@
 <resources>
     <string name="app_name">BarcodeScannerForEmployees</string>
-    <string name="action_settings">Settings</string>
+    <string name="settings">Settings</string>
     <string name="first_fragment_label">Add new product</string>
     <string name="second_fragment_label">Products</string>
     <string name="netWeight">Net weight</string>
@@ -87,4 +87,45 @@
     <string name="abstract_product_request">Please, scan a barcode in order to add product</string>
     <string name="no_barcode">No barcode present</string>
     <string name="no_barcode_button">No barcode</string>
+    <string name="register">Register</string>
+    <string name="login">Login</string>
+    <string name="offline">Offline</string>
+    <string name="username">Username</string>
+    <string name="password">Password</string>
+    <string name="username_already_exists">Such account already exists</string>
+    <string name="wrong_password">Wrong password</string>
+    <string name="server">Server</string>
+    <string name="my_account">My account</string>
+    <string name="my_groups">My groups</string>
+    <string name="nav_open">navigation open</string>
+    <string name="nav_close">Navigation close</string>
+    <string name="new_name">New name</string>
+    <string name="new_password">New password</string>
+    <string name="group_name">Group name</string>
+    <string name="group_password">Group password</string>
+    <string name="create_group">Create group</string>
+    <string name="join_group">Join group</string>
+    <string name="leave">Leave</string>
+    <string name="leave_group">Leave group</string>
+    <string name="rename_group">Rename group</string>
+    <string name="join_or_create_group">Join or create a group</string>
+    <string name="image_compress_factor">Image compression factor</string>
+    <string name="current_group">Current group</string>
+    <string name="cancel">Cancel</string>
+    <string name="no_internet_connection">Cannot reach the server. Maybe, you lost internet connection?</string>
+    <string name="ok">OK</string>
+    <string name="logout">Log out</string>
+    <string name="online_only_feature">This feature is online only</string>
+    <string name="username_changed">Your username has been changed. Please, relogin</string>
+    <string name="password_changed">You password was changed. Please, relogin</string>
+    <string name="new_group_name">Enter new group name</string>
+    <string name="kick">Kick</string>
+    <string name="transfer_ownership">Transfer ownership</string>
+    <string name="transfer_ownership_confirmation">Are you sure you want to transfer ownership on current group to that user?</string>
+    <string name="loading_please_wait">Loading, please wait</string>
+    <string name="loading">Loading</string>
+    <string-array name="languages">
+        <item>en-US</item>
+        <item>ru-RU</item>
+    </string-array>
 </resources>

gradle/libs.versions.toml

@@ -17,15 +17,19 @@ gridlayout = "1.0.0"
 activity = "1.9.2"
 legacySupportV4 = "1.0.0"
 fragment = "1.8.4"
+okhttp = "4.10.0"
 playServicesCodeScanner = "16.1.0"
+securityCrypto = "1.0.0"
 volley = "1.2.1"
 zxingAndroidEmbedded = "4.3.0"
+material3Android = "1.3.0"
 
 [libraries]
 androidx-camera-camera2 = { module = "androidx.camera:camera-camera2", version.ref = "cameraView" }
 androidx-camera-lifecycle = { module = "androidx.camera:camera-lifecycle", version.ref = "cameraView" }
 androidx-camera-view = { module = "androidx.camera:camera-view", version.ref = "cameraView" }
 androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
+androidx-security-crypto = { module = "androidx.security:security-crypto", version.ref = "securityCrypto" }
 barcode-scanning = { module = "com.google.mlkit:barcode-scanning", version.ref = "barcodeScanning" }
 junit = { group = "junit", name = "junit", version.ref = "junit" }
 androidx-junit = { group = "androidx.test.ext", name = "junit", version.ref = "junitVersion" }
@@ -40,9 +44,11 @@ androidx-gridlayout = { group = "androidx.gridlayout", name = "gridlayout", vers
 androidx-activity = { group = "androidx.activity", name = "activity", version.ref = "activity" }
 androidx-legacy-support-v4 = { group = "androidx.legacy", name = "legacy-support-v4", version.ref = "legacySupportV4" }
 androidx-fragment = { group = "androidx.fragment", name = "fragment", version.ref = "fragment" }
+okhttp = { module = "com.squareup.okhttp3:okhttp", version.ref = "okhttp" }
 play-services-code-scanner = { module = "com.google.android.gms:play-services-code-scanner", version.ref = "playServicesCodeScanner" }
 volley = { module = "com.android.volley:volley", version.ref = "volley" }
 zxing-android-embedded = { module = "com.journeyapps:zxing-android-embedded", version.ref = "zxingAndroidEmbedded" }
+androidx-material3-android = { group = "androidx.compose.material3", name = "material3-android", version.ref = "material3Android" }
 
 [plugins]
 android-application = { id = "com.android.application", version.ref = "agp" }