do not erase barcode on 'no barcode present' checkbox

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

@@ -48,6 +48,34 @@
                 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 +89,7 @@
         
         <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 +98,7 @@
         </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/Net.kt

@@ -0,0 +1,633 @@
+package org.foxarmy.barcodescannerforemployees
+
+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 kotlin.concurrent.thread
+
+class Net {
+    var language = "en-US"
+    var server = "bsfe.foxarmy.org"
+    var token = ""
+
+    fun requestProductFromOnlineDB(barcode: String): String {
+        var response = ""
+        thread {
+            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().body!!.string()
+        }.join()
+
+        return if (response == "") {
+            "Not found 404"
+        } else {
+            response
+        }
+    }
+
+    fun registerAccount(username: String, password: String): Response {
+        lateinit var response: Response
+        thread {
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+                .add("username", username)
+                .add("password", password)
+                .build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/user/register")
+                .post(body)
+                .addHeader("content-type", "application/x-www-form-urlencoded")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun login(username: String, password: String): Response {
+        lateinit var response: Response
+        thread {
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+                .add("username", username)
+                .add("password", password)
+                .build()
+            val requestLogin = Request.Builder()
+                .url("https://$server/api/user/login")
+                .post(body)
+                .addHeader("content-type", "application/x-www-form-urlencoded")
+                .addHeader("accept-language", language)
+                .build()
+            response = client.newCall(requestLogin).execute()
+        }.join()
+
+        return response
+    }
+
+    fun uploadAbstractProduct(groupId: Int, abstractProduct: AbstractProduct, imageFile: File): Response {
+        lateinit var response: Response
+
+        thread {
+            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 $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun changeUsername(newUsername: String): Response {
+
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+            body.add("username", newUsername)
+
+            val requestBody = body.build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/user/changeUsername")
+                .post(requestBody)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun changePassword(newPassword: String): Response {
+
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+            body.add("password", newPassword)
+
+            val requestBody = body.build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/user/changePassword")
+                .post(requestBody)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun createGroup(name: String, password: String): Response {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+
+            val requestBody = body.build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/group/create/$name")
+                .post(requestBody)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+            response = client.newCall(request).execute()
+        }.join()
+
+
+        changeGroupPassword(name, password)
+
+        return response
+    }
+
+    fun joinGroup(id: Int, password: String): Response {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+                .add("password", password)
+                .build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/group/join/$id")
+                .post(body)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun changeGroupPassword(name: String, password: String): Response {
+        lateinit var response: Response
+
+        thread {
+
+            val groupId = getGroupId(name);
+
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+            body.add("password", password)
+
+            val requestBody = body.build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/group/password/$groupId")
+                .post(requestBody)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun getGroupId(name: String): String {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/group/byName/$name")
+                .get()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+            response = client.newCall(request).execute()
+        }.join()
+
+        val responseText = response.body!!.string()
+
+        return responseText
+    }
+
+    fun getGroupName(id: Int): String {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/group/byId/$id")
+                .get()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+            response = client.newCall(request).execute()
+        }.join()
+
+        val responseText = response.body!!.string()
+
+        return responseText
+    }
+
+    fun getUsersInGroup(groupId: Int): Response {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/group/getUsers/$groupId")
+                .get()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun getMyGroups(): Response {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/user/myGroups")
+                .get()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun getUsernameById(userId: Int): Response {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/user/byId/$userId")
+                .get()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun getGroupAdminId(groupId: Int): Response {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/group/adminId/$groupId")
+                .get()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun updateAbstractProduct(groupId: Int, abstractProduct: AbstractProduct, imageFile: File): Response {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val body = MultipartBody.Builder()
+                .setType("multipart/form-data".toMediaType())
+                .addFormDataPart("file", imageFile.name, imageFile.asRequestBody("image/png".toMediaTypeOrNull()))
+                .addFormDataPart("groupId", groupId.toString())
+                .addFormDataPart("localId", abstractProduct.id.toString())
+                .addFormDataPart("barcode", abstractProduct.barcode)
+                .addFormDataPart("name", abstractProduct.name)
+                .addFormDataPart("net_weight", abstractProduct.netWeight.toString())
+                .addFormDataPart("category", abstractProduct.category.toString())
+                .addFormDataPart("unit", abstractProduct.unit.toString())
+                .build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/abstractproduct/update")
+                .post(body)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun uploadCategory(groupId: Int, category: Category): Response {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+                .add("localId", category.id.toString())
+                .add("categoryName", category.name)
+                .add("groupId", groupId.toString())
+                .build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/category/create")
+                .post(body)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun updateCategory(groupId: Int, category: Category): Response {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+                .add("localId", category.id.toString())
+                .add("categoryName", category.name)
+                .add("groupId", groupId.toString())
+                .build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/category/update")
+                .post(body)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun uploadProduct(groupId: Int, product: Product): Response {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+                .add("localId", product.id.toString())
+                .add("groupId", groupId.toString())
+                .add("abstract_product_id", product.abstractProductId.toString())
+                .add("amount", product.amount.toString())
+                .add("date_of_production", product.dateOfProduction.toString())
+                .add("expiry_date", product.dateOfExpiry.toString())
+                .build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/product/create")
+                .post(body)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun updateProduct(groupId: Int, product: Product): Response {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val body = FormBody.Builder()
+                .add("localId", product.id.toString())
+                .add("groupId", groupId.toString())
+                .add("abstract_product_id", product.abstractProductId.toString())
+                .add("amount", product.amount.toString())
+                .add("date_of_production", product.dateOfProduction.toString())
+                .add("expiry_date", product.dateOfExpiry.toString())
+                .build()
+
+            val request = Request.Builder()
+                .url("https://$server/api/product/update")
+                .post(body)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun synchronize(groupId: Int): Response {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/user/synchronize/$groupId")
+                .get()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun getProduct(groupId: Int, localId: Int): Response {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/product/$groupId/$localId")
+                .get()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun getAbstractProduct(groupId: Int, localId: Int): Response {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/abstractproduct/$groupId/$localId")
+                .get()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun downloadImage(url: String, file: File) {
+        thread {
+            val client = OkHttpClient()
+            val request = Request.Builder()
+                .url(url)
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            client.newCall(request).execute().use { response ->
+                if (!response.isSuccessful) throw IOException("Unexpected code $response")
+
+                val fos = FileOutputStream(file)
+
+                response.body?.byteStream()?.use { inputStream ->
+                    fos.use {
+                        inputStream.copyTo(fos)
+                    }
+                }
+            }
+        }.join()
+    }
+
+    fun deleteCategory(groupId: Int, localId: Int): Response {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/category/$groupId/$localId")
+                .delete()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun deleteAbstractProduct(groupId: Int, localId: Int): Response {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/abstractproduct/$groupId/$localId")
+                .delete()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+
+    fun deleteProduct(groupId: Int, localId: Int): Response {
+        lateinit var response: Response
+
+        thread {
+            val client = OkHttpClient()
+
+            val request = Request.Builder()
+                .url("https://$server/api/product/$groupId/$localId")
+                .delete()
+                .addHeader("Authorization", "Bearer $token")
+                .addHeader("accept-language", language)
+                .build()
+
+            response = client.newCall(request).execute()
+        }.join()
+
+        return response
+    }
+}

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

@@ -6,17 +6,26 @@ import android.content.ContextWrapper
 import android.graphics.Bitmap
 import android.graphics.BitmapFactory
 import android.graphics.Matrix
+import android.media.ExifInterface
 import android.net.Uri
 import android.os.Build
 import androidx.annotation.RequiresApi
 import androidx.core.content.FileProvider
 import com.google.firebase.components.BuildConfig
 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.*
 
+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)
 }
@@ -34,11 +43,18 @@ 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)
@@ -60,8 +76,6 @@ 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
@@ -95,3 +109,32 @@ fun getUnitNameById (context: Context, id: Int): String {
         else -> { "" }
     }
 }
+
+fun parseArray(input: String): IntArray {
+    return input.trim('[', ']').split(",").map { it.trim().toInt() }.toIntArray()
+}
+
+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()
+}

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

@@ -0,0 +1,48 @@
+package org.foxarmy.barcodescannerforemployees.activities
+
+import android.os.Bundle
+import android.widget.Toast
+import androidx.appcompat.app.AppCompatActivity
+import androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
+import org.foxarmy.barcodescannerforemployees.Net
+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 masterKeyAlias = MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC)
+
+        val sharedPreferences = EncryptedSharedPreferences.create(
+            "sensitive",
+            masterKeyAlias,
+            applicationContext,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        val net = Net()
+
+        net.server = sharedPreferences.getString("server", "bsfe.foxarmy.org")!!
+        net.language = sharedPreferences.getString("language", "")!!
+        net.token = sharedPreferences.getString("token", "")!!
+
+        binding.saveUsernameButton.setOnClickListener {
+            val response = net.changeUsername(binding.newUsernameTextEdit.text.toString())
+            Toast.makeText(this, response.body!!.string(), Toast.LENGTH_LONG).show()
+        }
+
+        binding.savePasswordButton.setOnClickListener {
+            val response = net.changePassword(binding.newPasswordTextEdit.text.toString())
+            Toast.makeText(this, response.body!!.string(), Toast.LENGTH_LONG).show()
+        }
+    }
+}

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

@@ -1,11 +1,14 @@
 package org.foxarmy.barcodescannerforemployees.activities
 
-import android.content.ContentValues
 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
@@ -14,12 +17,19 @@ import androidx.appcompat.app.AlertDialog
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.content.ContextCompat
 import androidx.core.widget.addTextChangedListener
+import androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
 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
@@ -47,11 +57,24 @@ class AddAbstractProductActivity : AppCompatActivity() {
 
     private var scanningBarcode = false
 
+    private lateinit var DAO: AbstractProductDAO
+    private lateinit var sharedPreferences: SharedPreferences
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
         setContentView(R.layout.fragment_add_abstract_product)
 
+        sharedPreferences = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            applicationContext,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        val dbHelper = DBStorageController(this, sharedPreferences.getString("currentGroup", "database")!!)
+        DAO = AbstractProductDAO(dbHelper)
 
         picturesPath = File(filesDir, "pictures")
         val thumbnailsDir = File(cacheDir, "thumbnails")
@@ -75,9 +98,7 @@ class AddAbstractProductActivity : AppCompatActivity() {
         fillupUnitsSpinner()
 
         noBarcodeCheckBox.setOnClickListener {
-            if (noBarcodeCheckBox.isChecked) {
-                barcodeText.setText("")
-            }
+            barcodeText.isEnabled = !noBarcodeCheckBox.isChecked
         }
 
         barcodeText.addTextChangedListener {
@@ -90,6 +111,7 @@ class AddAbstractProductActivity : AppCompatActivity() {
             "update" -> {
                 abstractProduct = extras.get("abstractProduct") as AbstractProduct?
             }
+
             "new_from_barcode" -> {
                 abstractProduct = extras.get("abstractProduct") as AbstractProduct?
                 barcode = abstractProduct!!.barcode
@@ -129,26 +151,35 @@ class AddAbstractProductActivity : AppCompatActivity() {
                 Toast.makeText(this, getString(R.string.product_net_weight_request), Toast.LENGTH_SHORT).show()
             }
 
-            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)
-            }
+            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", "offline")!!
+
+            lateinit var response: Response
+
+            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!!)
+                response = net.updateAbstractProduct(currentGroup.toInt(), abstractProduct!!, pictureFile)
+            } else if (action == "new" || action == "new_from_barcode") {
+                abstractProduct!!.id = DAO.addAbstractProduct(abstractProduct!!).toInt()
+                response = net.uploadAbstractProduct(currentGroup.toInt(), abstractProduct!!, pictureFile);
             }
+            Toast.makeText(this, response.body!!.string(), Toast.LENGTH_LONG).show()
 
             finish()
         }
@@ -165,15 +196,13 @@ class AddAbstractProductActivity : AppCompatActivity() {
 
     fun performRequest(barcode: String) {
         barcodeText.setText(this.barcode)
-        val requester = Requester("https://ean-online.ru", "match.php")
-        requester.request(this, barcode)
+        val net = Net();
+        val result = net.requestProductFromOnlineDB(barcode)
+        Log.d("QWERTYUIOP", "Result of request: $result")
+
         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 +211,8 @@ 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)
@@ -194,19 +221,17 @@ class AddAbstractProductActivity : AppCompatActivity() {
         }
 
         thread {
-            // Я сам в ахуях какой это костыль, пока хз как фиксить, потом придумаю :))
-            while (requester.response == "") {
-            }
-            if (requester.response == "Not found 404") {
+            if (result == "Not found 404") {
                 runOnUiThread {
                     Toast.makeText(this, getString(R.string.no_product_in_online_database), Toast.LENGTH_LONG)
                         .show()
+                    productNameText.setText("")
+                    netWeightText.setText("")
                 }
                 return@thread
             }
 
-            abstractProduct = Parser().parse(requester.response)
-            requester.response = ""
+            abstractProduct = Parser().parse(result)
             runOnUiThread {
                 productNameText.text = abstractProduct.name
                 netWeightText.text = abstractProduct.netWeight.toString()
@@ -224,40 +249,20 @@ 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 +272,35 @@ 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()
+            val imageHash = calculateMd5Hash(tempfile)
+//            val imageContent = tempfile.inputStream().readBytes()
+//            val imageHash = imageContent.toString(Charsets.UTF_8).md5()
 
             pictureFile = File(picturesPath, "$imageHash.png")
             Files.move(tempfile.toPath(), pictureFile.toPath(), StandardCopyOption.REPLACE_EXISTING)
             tempfile.delete()
+
+            val imageContent = pictureFile.inputStream().readBytes()
+            var img = BitmapFactory.decodeByteArray(imageContent, 0, imageContent.size)
+
+            val exif = ExifInterface(pictureFile.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(pictureFile)
+            )
+
             generateThumbnailForImage(this, imageHash)
 
             imageView.setImageURI(getImageUri(this, pictureFile))
@@ -303,7 +331,8 @@ 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.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 androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
+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
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
         setContentView(R.layout.activity_add_category)
 
+        sharedPreferences = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            applicationContext,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        val dbHelper = DBStorageController(this, sharedPreferences.getString("currentGroup", "offline")!!)
+        DAO = CategoryDAO(dbHelper)
+
         val extras = intent.extras
         val category = extras!!.get("category") as Category?
 
@@ -25,25 +42,28 @@ 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 = sharedPreferences.getString("currentGroup", "offline")!!.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
             }
 
             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()
+                net.uploadCategory(currentGroup, newCategory)
             } 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)
+                net.updateCategory(currentGroup, category)
             }
 
             finish()

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

@@ -2,6 +2,7 @@ package org.foxarmy.barcodescannerforemployees.activities
 
 import android.app.Activity
 import android.content.Intent
+import android.content.SharedPreferences
 import android.os.Build
 import android.os.Bundle
 import android.view.View
@@ -12,11 +13,17 @@ import androidx.appcompat.app.AlertDialog
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.content.ContextCompat
 import androidx.core.widget.addTextChangedListener
+import androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
 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 +52,28 @@ 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
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
         setContentView(R.layout.fragment_add_product)
 
+        sharedPreferences = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            applicationContext,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        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()
@@ -147,12 +177,22 @@ class AddProductActivity : AppCompatActivity() {
                 return@setOnClickListener
             }
 
+            val currentGroup: Int = if (sharedPreferences.getString("currentGroup", "")!! == "") 0 else sharedPreferences.getString("currentGroup", "")!!.toInt()
+
+            var response: Response? = null
+
             if (updatingExistentProduct) {
-                DBStorageController(this).updateProduct(DBStorageController(this).writableDatabase, product!!)
+                productDAO.updateProduct(product!!)
+                if (currentGroup > 0) response = net.updateProduct(currentGroup, product!!)
             } else {
-                DBStorageController(this).insertNewProduct(DBStorageController(this).writableDatabase, product!!)
+                product!!.id = productDAO.insertNewProduct(product!!).toInt()
+                if (currentGroup > 0) response = net.uploadProduct(currentGroup, product!!)
             }
 
+            if (response != null) {
+                Toast.makeText(this, response.body!!.string(), Toast.LENGTH_LONG).show()
+            }   
+
             finish()
         }
         update()
@@ -245,7 +285,7 @@ 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 +2,41 @@ 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 androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
 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 = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            applicationContext,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        val dbHelper = DBStorageController(this, sharedPreferences.getString("currentGroup", "database")!!)
+        productDAO = ProductDAO(dbHelper)
+
         fillUp()
     }
 
@@ -31,7 +49,7 @@ 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/GroupActivity.kt

@@ -0,0 +1,81 @@
+package org.foxarmy.barcodescannerforemployees.activities
+
+import android.content.Intent
+import android.os.Bundle
+import android.widget.Toast
+import androidx.appcompat.app.AppCompatActivity
+import androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
+import org.foxarmy.barcodescannerforemployees.Net
+import org.foxarmy.barcodescannerforemployees.databinding.ActivityGroupBinding
+
+class GroupActivity : AppCompatActivity() {
+
+    private lateinit var binding: ActivityGroupBinding
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        binding = ActivityGroupBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+
+        val sharedPreferences = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            applicationContext,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        binding.createGroupButton.setOnClickListener {
+            val groupName = binding.groupNameTextEdit.text.toString()
+            val groupPassword = binding.groupPasswordTextEdit.text.toString()
+            // group is set to "successful"
+            val n = Net()
+            n.language = sharedPreferences.getString("language", "en-US")!!
+            n.server = sharedPreferences.getString("server", "")!!
+            n.token = sharedPreferences.getString("token", "")!!
+
+            val response = n.createGroup(groupName, groupPassword)
+            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()
+                val intent = Intent(this, MainActivity::class.java)
+                startActivity(intent)
+                finish()
+            } else {
+                Toast.makeText(this, responseText, Toast.LENGTH_LONG).show()
+            }
+        }
+
+        binding.joinGroupButton.setOnClickListener {
+            val groupName = binding.groupNameTextEdit.text.toString()
+            val groupPassword = binding.groupPasswordTextEdit.text.toString()
+
+            val n = Net()
+            n.language = sharedPreferences.getString("language", "en-US")!!
+            n.server = sharedPreferences.getString("server", "")!!
+            n.token = sharedPreferences.getString("token", "")!!
+
+            val groupId = n.getGroupId(groupName).toInt()
+            val response = n.joinGroup(groupId, groupPassword)
+            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()
+                val intent = Intent(this, MainActivity::class.java)
+                startActivity(intent)
+                finish()
+            } else {
+                Toast.makeText(this, responseText, Toast.LENGTH_LONG).show()
+            }
+        }
+    }
+}

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

@@ -0,0 +1,106 @@
+package org.foxarmy.barcodescannerforemployees.activities
+
+import android.content.Intent
+import android.os.Bundle
+import android.widget.ArrayAdapter
+import android.widget.Toast
+import androidx.appcompat.app.AppCompatActivity
+import androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
+import org.foxarmy.barcodescannerforemployees.Net
+import org.foxarmy.barcodescannerforemployees.R
+import org.foxarmy.barcodescannerforemployees.databinding.ActivityLoginBinding
+import org.foxarmy.barcodescannerforemployees.parseArray
+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)
+
+        fillUpLanguagesSpinner()
+
+        val sharedPreferences = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            applicationContext,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        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 n = Net()
+            n.language = sharedPreferences.getString("language", "en-US")!!
+            n.server = server
+
+            val response = n.login(username, password)
+            val responseText = response.body!!.string()
+            if (response.code != 200) {
+                Toast.makeText(this, responseText, Toast.LENGTH_SHORT).show()
+            } else {
+                val json = JSONObject(responseText)
+                sharedPreferences.edit().putString("token", json["token"].toString()).apply()
+                n.token = json["token"].toString()
+                sharedPreferences.edit().putInt("userId", json["id"].toString().toInt()).apply()
+                sharedPreferences.edit().putString("server", server).apply()
+
+
+                val r = n.getMyGroups().body!!.string()
+                val myGroups = parseArray(r).map { a -> a.toString()}
+
+                sharedPreferences.edit().putStringSet("groups", myGroups.toSet()).apply()
+                sharedPreferences.edit().putString("currentGroup", myGroups[0]).apply()
+
+                val intent = Intent(this, MainActivity::class.java)
+                startActivity(intent)
+                finish()
+            }
+        }
+
+        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 n = Net()
+            n.language = language
+            n.server = server
+            val response = n.registerAccount(username, password);
+            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()
+                val token = JSONObject(n.login(username, password).body!!.string())["token"].toString()
+                sharedPreferences.edit().putString("token", token).apply()
+
+                sharedPreferences.edit().putString("server", server).apply()
+                val intent = Intent(this, GroupActivity::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
+    }
+
+}

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

@@ -1,26 +1,47 @@
 package org.foxarmy.barcodescannerforemployees.activities
 
+import android.app.Activity
 import android.content.DialogInterface
 import android.content.Intent
 import android.os.Bundle
 import android.view.Menu
 import android.view.MenuItem
+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.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
 import androidx.viewpager.widget.ViewPager
+import com.google.android.material.navigation.NavigationView
+import org.foxarmy.barcodescannerforemployees.Net
 import org.foxarmy.barcodescannerforemployees.R
 import org.foxarmy.barcodescannerforemployees.ViewPagerAdapter
+import org.foxarmy.barcodescannerforemployees.convertToUnixEpochTimestamp
+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
+    var drawerLayout: DrawerLayout? = null
+    var actionBarDrawerToggle: ActionBarDrawerToggle? = null
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -32,6 +53,16 @@ class MainActivity : AppCompatActivity() {
         setupViewPager(binding.tabViewpager)
         binding.tabTablayout.setupWithViewPager(binding.tabViewpager)
 
+        drawerLayout = binding.drawerLayout
+        actionBarDrawerToggle = ActionBarDrawerToggle(this, drawerLayout, R.string.nav_open, R.string.nav_close)
+
+        drawerLayout!!.addDrawerListener(actionBarDrawerToggle!!)
+        actionBarDrawerToggle!!.syncState()
+        binding.navView.setNavigationItemSelectedListener(this)
+
+        // to make the Navigation drawer icon always appear on the action bar
+        supportActionBar!!.setDisplayHomeAsUpEnabled(true)
+
         binding.expiryCalendarFab.setOnClickListener { _ ->
             val expiryCalendarIntent = Intent(this, ExpiryCalendarActivity::class.java)
             val extras = Bundle()
@@ -69,6 +100,269 @@ class MainActivity : AppCompatActivity() {
                     extras.putParcelable("product", null)
                     addProductIntent.putExtras(extras)
                     ContextCompat.startActivity(this, addProductIntent, extras)
+
+                }
+            }
+        }
+        synchronize()
+    }
+
+    private fun synchronize() {
+
+        val sharedPreferences = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            applicationContext,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        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()
+
+        val data = JSONObject(net.synchronize(currentGroup).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()) {
+
+                    var updatedData: Category
+
+                    with(categoryInRemoteDB) {
+                        updatedData = Category(
+                            this["local_id"].toString().toInt(),
+                            this["name"].toString()
+                        )
+                    }
+
+                    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) {
+                var newProduct: Product
+
+                with(remoteProduct) {
+                    newProduct = Product(
+                        this["local_id"].toString().toInt(),
+                        this["abstract_product_id"].toString().toInt(),
+                        this["amount"].toString().toInt(),
+                        convertToUnixEpochTimestamp(this["date_of_production"].toString()),
+                        convertToUnixEpochTimestamp(this["expiry_date"].toString())
+                    )
+                }
+
+                productDAO.insertNewProduct(newProduct)
+            }
+
+            if (productInRemoteDB != null && productInLocalDB != null) {
+                if (productInRemoteDB["hash"] != productInLocalDB.calculateHash()) {
+
+                    var updatedData: Product
+
+                    with(productInRemoteDB) {
+                        updatedData = Product(
+                            this["local_id"].toString().toInt(),
+                            this["abstract_product_id"].toString().toInt(),
+                            this["amount"].toString().toInt(),
+                            convertToUnixEpochTimestamp(this["date_of_production"].toString()),
+                            convertToUnixEpochTimestamp(this["expiry_date"].toString())
+                        )
+                    }
+
+                    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)
+
+                var newAbstractProduct: AbstractProduct
+
+                with(remoteAbstractProduct) {
+                    newAbstractProduct = AbstractProduct(
+                        this["local_id"].toString().toInt(),
+                        this["barcode"].toString(),
+                        this["name"].toString(),
+                        this["net_weight"].toString().toDouble(),
+                        this["image_filename"].toString(),
+                        this["category"].toString().toInt(),
+                        this["unit"].toString().toInt()
+                    )
+                }
+
+                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)
+
+                    var updatedData: AbstractProduct
+
+                    with(abstractProductInRemoteDB) {
+                        updatedData = AbstractProduct(
+                            this["local_id"].toString().toInt(),
+                            this["barcode"].toString(),
+                            this["name"].toString(),
+                            this["net_weight"].toString().toDouble(),
+                            this["image_filename"].toString(),
+                            this["category"].toString().toInt(),
+                            this["unit"].toString().toInt()
+                        )
+                    }
+
+
+                    abstractProductDAO.updateAbstractProduct(updatedData)
                 }
             }
         }
@@ -81,84 +375,129 @@ 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
     }
 
     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)
-
-        return when (item.itemId) {
-
-
-            R.id.action_settings -> {
-                true
+    override fun onNavigationItemSelected(item: MenuItem): Boolean {
+        lateinit var intent: Intent
+        when (item.itemId) {
+            R.id.nav_account -> {
+                intent = Intent(this, AccountSettingsActivity::class.java)
+                settingsActivityLauncher.launch(intent)
+                return 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.nav_groups -> {
+                intent = Intent(this, MyGroupsActivity::class.java)
             }
 
-            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
+            R.id.nav_settings -> {
+                intent = Intent(this, SettingsActivity::class.java)
             }
-
-            else -> super.onOptionsItemSelected(item)
         }
+        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() {
+        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()
+    }
+
+    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) {

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

@@ -0,0 +1,76 @@
+package org.foxarmy.barcodescannerforemployees.activities
+
+import android.content.Context
+import android.os.Bundle
+import android.view.View
+import androidx.appcompat.app.AppCompatActivity
+import androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
+import org.foxarmy.barcodescannerforemployees.Net
+import org.foxarmy.barcodescannerforemployees.databinding.ActivityManageGroupBinding
+import org.foxarmy.barcodescannerforemployees.parseArray
+import org.foxarmy.barcodescannerforemployees.views.GroupMemberView
+
+class ManageGroupActivity : AppCompatActivity(){
+    private lateinit var binding: ActivityManageGroupBinding
+    private var isAdmin: Boolean = true
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        binding = ActivityManageGroupBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+
+        val groupId = intent.extras!!.getInt("groupId")
+
+        val masterKeyAlias = MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC)
+
+        val sharedPreferences = EncryptedSharedPreferences.create(
+            "sensitive",
+            masterKeyAlias,
+            applicationContext,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        val net = Net()
+
+        net.token = sharedPreferences.getString("token", "")!!
+        net.server = sharedPreferences.getString("server", "")!!
+        net.language = sharedPreferences.getString("language", "en-US")!!
+
+
+        val users = parseArray(net.getUsersInGroup(groupId).body!!.string())
+
+        for (user in users) {
+            val groupMemberView = GroupMemberView(this, this as Context, net.getUsernameById(user).body!!.string(), user)
+
+            binding.groupsContent.addView(groupMemberView)
+        }
+
+        isAdmin = amIAnAdminIn(groupId)
+
+        if (!isAdmin) {
+            binding.renameButton.visibility = View.GONE
+        }
+    }
+
+    fun amIAnAdminIn(groupId: Int): Boolean {
+        val sharedPreferences = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            applicationContext,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        val net = Net()
+
+        net.token = sharedPreferences.getString("token", "")!!
+        net.server = sharedPreferences.getString("server", "")!!
+        net.language = sharedPreferences.getString("language", "en-US")!!
+
+        val result = sharedPreferences.getInt("userId", 0) == net.getGroupAdminId(groupId).body!!.string().toInt()
+        return result
+    }
+}

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 androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
+import org.foxarmy.barcodescannerforemployees.Net
+import org.foxarmy.barcodescannerforemployees.R
+import org.foxarmy.barcodescannerforemployees.databinding.ActivityMyGroupsBinding
+import org.foxarmy.barcodescannerforemployees.parseArray
+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 = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            applicationContext,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        val net = Net()
+
+        net.token = sharedPreferences.getString("token", "")!!
+        net.server = sharedPreferences.getString("server", "")!!
+        net.language = sharedPreferences.getString("language", "en-US")!!
+
+        val groups = parseArray(net.getMyGroups().body!!.string())
+
+        val container = findViewById<LinearLayout>(R.id.groupsLayout)
+
+        for (group in groups) {
+            val groupView = GroupView(this, this as Context, net.getGroupName(group), group)
+
+
+            container.addView(groupView)
+        }
+
+        binding.newGroup.setOnClickListener {
+            val intent = Intent(this, GroupActivity::class.java)
+            startActivity(intent)
+        }
+    }
+}

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

@@ -0,0 +1,47 @@
+package org.foxarmy.barcodescannerforemployees.activities
+
+import android.app.Activity
+import android.content.Intent
+import android.content.SharedPreferences
+import android.os.Bundle
+import androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
+
+class NavigatorActivity : Activity() {
+
+    private lateinit var sharedPreferences: SharedPreferences
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        sharedPreferences = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            applicationContext,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        var intent = Intent(this, MainActivity::class.java)
+
+        if (!isInGroup()) {
+            intent = Intent(this, GroupActivity::class.java)
+        }
+
+        if (!isAuthenticated()) {
+            intent = Intent(this, LoginActivity::class.java);
+        }
+
+
+        startActivity(intent);
+        finish();
+    }
+
+    private fun isAuthenticated(): Boolean {
+        return sharedPreferences.getString("token", "") != ""
+    }
+
+    private fun isInGroup(): Boolean {
+        return sharedPreferences.getStringSet("groups", emptySet())!!.isNotEmpty()
+    }
+}

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

@@ -0,0 +1,83 @@
+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 androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
+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>
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        sharedPreferences = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            applicationContext,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        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", "")!!
+
+        groupsNames = mutableListOf()
+
+        for (myGroup in myGroups) {
+            groupsNames.add(net.getGroupName(myGroup.toInt()))
+        }
+
+        binding = ActivitySettingsBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+
+        setUpImageCompressionSeekBar()
+        fillUpCurrentGroupSpinner()
+
+        binding.saveButton.setOnClickListener {
+            sharedPreferences.edit().putString("currentGroup", net.getGroupId(binding.currentGroupSpinner.selectedItem.toString())).apply()
+            sharedPreferences.edit().putInt("imageCompression", binding.imageCompressionFactorSeekBar.progress + 1).apply()
+            setResult(Activity.RESULT_OK)
+            finish()
+        }
+
+        binding.cancelButton.setOnClickListener {
+            setResult(Activity.RESULT_CANCELED)
+            finish()
+        }
+    }
+
+    private fun setUpImageCompressionSeekBar() {
+        val compressionFactor = sharedPreferences.getInt("imageCompression", 1)
+        binding.imageCompressionFactorSeekBar.progress = compressionFactor - 1
+    }
+
+    private fun fillUpCurrentGroupSpinner() {
+
+
+        if (currentGroup == "offline") {
+            binding.currentGroupSetting.visibility = View.GONE
+        }
+
+        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
+        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(android.provider.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} = ?"
+                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 +2,7 @@ package org.foxarmy.barcodescannerforemployees.dataclasses
 
 import android.os.Parcel
 import android.os.Parcelable
+import org.foxarmy.barcodescannerforemployees.md5
 
 class AbstractProduct() : Parcelable {
     var id: Int = 0
@@ -32,6 +33,10 @@ 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)

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

@@ -2,6 +2,7 @@ package org.foxarmy.barcodescannerforemployees.dataclasses
 
 import android.os.Parcel
 import android.os.Parcelable
+import org.foxarmy.barcodescannerforemployees.md5
 
 class Category() : Parcelable {
     var id = 0
@@ -27,6 +28,10 @@ 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)

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

@@ -5,6 +5,7 @@ import android.os.Parcel
 import android.os.Parcelable
 import androidx.annotation.RequiresApi
 import org.foxarmy.barcodescannerforemployees.calculateProductFreshness
+import org.foxarmy.barcodescannerforemployees.md5
 
 class Product() : Parcelable {
     var id = 0
@@ -46,6 +47,10 @@ 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)

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 +11,39 @@ 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 androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
+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.views.CategoryView
 
 class CategoriesFragment : Fragment() {
+
+    private lateinit var sharedPreferences: SharedPreferences
+    private lateinit var categoryDAO: CategoryDAO
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        sharedPreferences = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            requireContext(),
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        prepareDatabaseConnection()
+    }
+
+    private fun prepareDatabaseConnection() {
+        val dbHelper = DBStorageController(requireContext(), sharedPreferences.getString("currentGroup", "database")!!)
+        categoryDAO = CategoryDAO(dbHelper)
+    }
+
     override fun onCreateView(
         inflater: LayoutInflater, container: ViewGroup?,
         savedInstanceState: Bundle?
@@ -35,11 +60,21 @@ class CategoriesFragment : Fragment() {
     fun removeSelected() {
         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())
+                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())
+                val response = net.deleteCategory(currentGroup, view.category.id)
+                activity!!.runOnUiThread{
+                    Toast.makeText(context, response.body!!.string(), Toast.LENGTH_SHORT).show()
+                }
+
                 deleted = true
             }
         }
@@ -64,28 +99,15 @@ class CategoriesFragment : Fragment() {
     }
 
     fun updateContent() {
+        prepareDatabaseConnection()
         val layout = view?.findViewById<LinearLayout>(R.id.categoriesLayout)
         layout?.removeAllViews()
 
-        val db = DBStorageController(requireContext()).readableDatabase
+        val categories = categoryDAO.getAllCategories()
 
-        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)
-            }
+        for (category in categories) {
+            val categoryView = CategoryView(requireActivity(), requireContext(), category)
+            layout?.addView(categoryView)
         }
     }
 

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 +14,14 @@ 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 androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
+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.views.ProductView
 import kotlin.concurrent.thread
 
@@ -32,6 +32,24 @@ 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 = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            requireContext(),
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        prepareDatabaseConnection()
+
+    }
+
     override fun onCreateView(
         inflater: LayoutInflater, container: ViewGroup?,
         savedInstanceState: Bundle?
@@ -61,6 +79,11 @@ 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)
 
@@ -99,6 +122,7 @@ class ShelfFragment : Fragment() {
     }
 
     fun updateContent() {
+        prepareDatabaseConnection()
         thread {
             if (updateInProgress) return@thread
             updateInProgress = true
@@ -107,88 +131,7 @@ class ShelfFragment : Fragment() {
                 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(
@@ -201,6 +144,7 @@ class ShelfFragment : Fragment() {
                 }
             }
             updateInProgress = false
+
         }
     }
 
@@ -208,14 +152,24 @@ 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)
+                    val response = net.deleteProduct(currentGroup, view.product.id)
+                    activity!!.runOnUiThread{
+                        Toast.makeText(context, response.body!!.string(), Toast.LENGTH_SHORT).show()
+                    }
+
                     deleted = true
                 }
             }

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

@@ -1,8 +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
@@ -10,13 +10,15 @@ import android.widget.*
 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 androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
+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.views.AbstractProductView
 import kotlin.concurrent.thread
@@ -26,10 +28,25 @@ 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
+
+
     override fun onCreateView(
         inflater: LayoutInflater, container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View {
+        sharedPreferences = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            requireContext(),
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        prepareDatabaseConnection()
+
         binding = FragmentStorageBinding.inflate(inflater)
 
         fillUpSortBySpinner()
@@ -55,6 +72,11 @@ 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 +94,24 @@ 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())
+                    val response = net.deleteAbstractProduct(currentGroup, view.abstractProduct.id)
+                    activity!!.runOnUiThread{
+                        Toast.makeText(context, response.body!!.string(), Toast.LENGTH_SHORT).show()
+                    }
+
                     deleted = true
                 }
             }
@@ -109,84 +141,36 @@ class StorageFragment : Fragment() {
     }
 
     fun updateContent() {
+        prepareDatabaseConnection()
         thread {
             val grv = binding.contentGridLayout
             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)
-                        }
-                        abstractProduct.findViewById<TextView>(R.id.productNameView).setOnClickListener {
-                            (activity as FindBarcodelessAbstractProduct).selected(abstractProduct.abstractProduct)
-
-                        }
+                if (filterBy == "barcodeless") {
+                    abstractProductView.setOnClickListener {
+                        (activity as FindBarcodelessAbstractProduct).selected(abstractProductView.abstractProduct)
                     }
-
-                    activity!!.runOnUiThread{
-                        grv.addView(abstractProduct)
+                    abstractProductView.findViewById<TextView>(R.id.productNameView).setOnClickListener {
+                        (activity as FindBarcodelessAbstractProduct).selected(abstractProductView.abstractProduct)
                     }
                 }
+
+                activity!!.runOnUiThread{
+                    grv.addView(abstractProductView)
+                }
             }
         }.join()
     }
@@ -202,6 +186,7 @@ class StorageFragment : Fragment() {
         filter = arrayOf("$id")
         updateContent()
     }
+
     companion object {
 
         fun newInstance(filterBy: String, filter: Array<String>):StorageFragment = StorageFragment().apply {

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
@@ -13,9 +14,16 @@ import android.widget.Toast
 import androidx.constraintlayout.widget.ConstraintLayout
 import androidx.core.content.ContextCompat
 import androidx.core.content.ContextCompat.startActivity
-import org.foxarmy.barcodescannerforemployees.*
+import androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
+import org.foxarmy.barcodescannerforemployees.R
 import org.foxarmy.barcodescannerforemployees.activities.FullscreenActivity
+import org.foxarmy.barcodescannerforemployees.database.CategoryDAO
+import org.foxarmy.barcodescannerforemployees.database.DBStorageController
 import org.foxarmy.barcodescannerforemployees.dataclasses.AbstractProduct
+import org.foxarmy.barcodescannerforemployees.getActivity
+import org.foxarmy.barcodescannerforemployees.getImageUri
+import org.foxarmy.barcodescannerforemployees.getUnitNameById
 import java.io.File
 
 class AbstractProductView: LinearLayout {
@@ -27,12 +35,26 @@ 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
         inflater.inflate(R.layout.abstract_product_view, this)
+
+        sharedPreferences = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            context,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        val dbHelper = DBStorageController(context, sharedPreferences.getString("currentGroup", "database")!!)
+        categoryDAO = CategoryDAO(dbHelper)
     }
 
     constructor(activity: Activity, context: Context, abstractProduct: AbstractProduct) : super(context) {
@@ -41,6 +63,16 @@ class AbstractProductView: LinearLayout {
         val inflater:LayoutInflater = activity.layoutInflater
         inflater.inflate(R.layout.abstract_product_view, this)
 
+        sharedPreferences = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            context,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        val dbHelper = DBStorageController(context, sharedPreferences.getString("currentGroup", "database")!!)
+        categoryDAO = CategoryDAO(dbHelper)
         update()
     }
 
@@ -89,6 +121,6 @@ class AbstractProductView: LinearLayout {
 
         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)
     }
 }

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

@@ -2,13 +2,17 @@ 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 androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
 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
 
 class CategoryView : LinearLayout {
@@ -17,9 +21,23 @@ class CategoryView : LinearLayout {
     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 = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            context,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        val dbHelper = DBStorageController(context, sharedPreferences.getString("currentGroup", "database")!!)
+        abstractProductDAO = AbstractProductDAO(dbHelper)
+
         val inflater: LayoutInflater = activity.layoutInflater
         inflater.inflate(R.layout.category_view, this)
 
@@ -29,7 +47,7 @@ class CategoryView : LinearLayout {
         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

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

@@ -2,21 +2,39 @@ 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 androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
 import org.foxarmy.barcodescannerforemployees.R
 import org.foxarmy.barcodescannerforemployees.activities.ExpiryCalendarActivity
+import org.foxarmy.barcodescannerforemployees.database.DBStorageController
+import org.foxarmy.barcodescannerforemployees.database.ProductDAO
 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 = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            context,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        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 +42,13 @@ 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
+    private 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
@@ -20,10 +21,18 @@ import androidx.core.graphics.blue
 import androidx.core.graphics.green
 import androidx.core.graphics.red
 import androidx.core.math.MathUtils.clamp
-import org.foxarmy.barcodescannerforemployees.*
+import androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKeys
+import org.foxarmy.barcodescannerforemployees.R
 import org.foxarmy.barcodescannerforemployees.activities.FullscreenActivity
+import org.foxarmy.barcodescannerforemployees.calculateProductFreshness
+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 org.foxarmy.barcodescannerforemployees.getActivity
+import org.foxarmy.barcodescannerforemployees.getImageUri
 import java.io.File
 import java.text.DecimalFormat
 import java.text.SimpleDateFormat
@@ -33,7 +42,7 @@ import kotlin.concurrent.thread
 class ProductView: LinearLayout {
     var product: Product = Product()
     var isProductSelected = false
-    private lateinit var activity: Activity
+    private var activity: Activity
 
     private lateinit var productImageView: ImageView
     private lateinit var productNameTextView: TextView
@@ -47,8 +56,25 @@ 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 = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            context,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        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 +86,18 @@ class ProductView: LinearLayout {
         val inflater: LayoutInflater = activity.layoutInflater
         inflater.inflate(R.layout.product_view, this)
 
+        sharedPreferences = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            context,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+
+        val dbHelper = DBStorageController(context, sharedPreferences.getString("currentGroup", "offline")!!)
+        abstractProductDAO = AbstractProductDAO(dbHelper)
+        categoryDAO = CategoryDAO(dbHelper)
+
         productImageView = findViewById(R.id.productPicture)
         productNameTextView = findViewById(R.id.productNameView)
         productNetWeightTextView = findViewById(R.id.productNetWeightView)
@@ -77,7 +115,7 @@ class ProductView: LinearLayout {
         productImageView.setOnClickListener {
             val fullscreenIntent = Intent(activity, FullscreenActivity::class.java)
             val extras = Bundle()
-            val abstractProduct = DBStorageController(context).findAbstractProductById(DBStorageController(context).readableDatabase, product.abstractProductId)
+            val abstractProduct = abstractProductDAO.findAbstractProductById(product.abstractProductId)
             extras.putString("imagehash", abstractProduct!!.imageHash)
             fullscreenIntent.putExtras(extras)
             startActivity(context, fullscreenIntent, extras)
@@ -88,11 +126,7 @@ class ProductView: LinearLayout {
 
     @RequiresApi(Build.VERSION_CODES.O)
     fun update () {
-        val linkedAbstractProduct: AbstractProduct? = DBStorageController(activity).findAbstractProductById(DBStorageController(activity).readableDatabase, product.abstractProductId)
-
-        if(linkedAbstractProduct == null) {
-            return
-        }
+        val linkedAbstractProduct: AbstractProduct = abstractProductDAO.findAbstractProductById(product.abstractProductId) ?: return
 
         val thumbnailsDir = File(activity.cacheDir, "thumbnails")
         thumbnailsDir.mkdirs()
@@ -104,7 +138,7 @@ class ProductView: LinearLayout {
         productNameTextView.text = linkedAbstractProduct.name
         productNetWeightTextView.text = linkedAbstractProduct.netWeight.toString()
         productAmountTextView.text = product.amount.toString()
-        productCategoryView.text = DBStorageController(activity).getCategoryNameById(DBStorageController(activity).readableDatabase, linkedAbstractProduct.category)
+        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) {

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/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_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 +1,74 @@
 <?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="777dp"
+                    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"/>
+            <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/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 +1,15 @@
+<?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"/>
+</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/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 +87,35 @@
         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-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 +87,33 @@
     <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-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" }