synchronizing

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

@@ -5,7 +5,11 @@ 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 {
@@ -383,4 +387,190 @@ class Net {
 
         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()
+    }
 }

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

@@ -12,11 +12,19 @@ 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)
 }
@@ -60,8 +68,6 @@ 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
@@ -98,4 +104,29 @@ fun getUnitNameById (context: Context, id: Int): String {
 
 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/AddAbstractProductActivity.kt

@@ -154,7 +154,7 @@ class AddAbstractProductActivity : AppCompatActivity() {
             net.server = sharedPreferences.getString("server", "")!!
             net.language = sharedPreferences.getString("language", "en-US")!!
 
-            val currentGroup = sharedPreferences.getString("currentGroup", "")!!
+            val currentGroup = sharedPreferences.getString("currentGroup", "offline")!!
 
             lateinit var response: Response
 
@@ -164,7 +164,7 @@ class AddAbstractProductActivity : AppCompatActivity() {
                 productName,
                 netWeight.toString().toDouble(),
                 pictureFile.nameWithoutExtension,
-                categorySpinner.selectedItemPosition,
+                categorySpinner.selectedItemPosition + 1,
                 unitTypeSpinner.selectedItemPosition
             )
             val pictureFile = File(File(filesDir, "pictures"), "${abstractProduct!!.imageHash}.png")
@@ -269,8 +269,9 @@ 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 = calculateMd5Hash(tempfile)
-            val imageHash = imageContent.toString(Charsets.UTF_8).md5()
+//            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)

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

@@ -8,6 +8,7 @@ import android.widget.EditText
 import android.widget.Toast
 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
@@ -31,7 +32,7 @@ class AddCategoryActivity : Activity() {
             EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
         )
 
-        val dbHelper = DBStorageController(this, sharedPreferences.getString("currentGroup", "database")!!)
+        val dbHelper = DBStorageController(this, sharedPreferences.getString("currentGroup", "offline")!!)
         DAO = CategoryDAO(dbHelper)
 
         val extras = intent.extras
@@ -41,6 +42,14 @@ class AddCategoryActivity : Activity() {
 
         categoryNameTextEdit.setText(category!!.name)
 
+        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()
@@ -48,9 +57,13 @@ class AddCategoryActivity : Activity() {
             }
 
             if (category.id == 0) { // Inserting new category
-                DAO.addCategory(Category(0, categoryNameTextEdit.text.toString()))
+                val newCategory = Category(0, categoryNameTextEdit.text.toString())
+                newCategory.id = DAO.addCategory(newCategory).toInt()
+                net.uploadCategory(currentGroup, newCategory)
             } else { // Updating existing category
+                category.name = categoryNameTextEdit.text.toString()
                 DAO.updateCategory(category)
+                net.updateCategory(currentGroup, category)
             }
 
             finish()

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

@@ -18,6 +18,8 @@ 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.Net
 import org.foxarmy.barcodescannerforemployees.R
 import org.foxarmy.barcodescannerforemployees.database.AbstractProductDAO
 import org.foxarmy.barcodescannerforemployees.database.DBStorageController
@@ -67,10 +69,11 @@ class AddProductActivity : AppCompatActivity() {
             EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
         )
 
-        val dbHelper = DBStorageController(this, sharedPreferences.getString("currentGroup", "database")!!)
+        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)
@@ -137,6 +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()
@@ -168,12 +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) {
                 productDAO.updateProduct(product!!)
+                if (currentGroup > 0) response = net.updateProduct(currentGroup, product!!)
             } else {
-                productDAO.insertNewProduct(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()

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

@@ -57,9 +57,11 @@ class LoginActivity : AppCompatActivity() {
 
 
                 val r = n.getMyGroups().body!!.string()
-                val myGroups = parseArray(r)
+                val myGroups = parseArray(r).map { a -> a.toString()}
+
+                sharedPreferences.edit().putStringSet("groups", myGroups.toSet()).apply()
+                sharedPreferences.edit().putString("currentGroup", myGroups[0]).apply()
 
-                sharedPreferences.edit().putStringSet("groups", myGroups.map { a -> a.toString()}.toSet())
                 val intent = Intent(this, MainActivity::class.java)
                 startActivity(intent)
                 finish()

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

@@ -1,6 +1,5 @@
 package org.foxarmy.barcodescannerforemployees.activities
 
-//import android.R
 import android.content.DialogInterface
 import android.content.Intent
 import android.os.Bundle
@@ -11,15 +10,28 @@ 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(), NavigationView.OnNavigationItemSelectedListener {
@@ -90,6 +102,234 @@ class MainActivity : AppCompatActivity(), NavigationView.OnNavigationItemSelecte
                 }
             }
         }
+        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 (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 (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 (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)
+                }
+            }
+        }
     }
 
     private fun setupViewPager(viewpager: ViewPager) {
@@ -117,9 +357,11 @@ class MainActivity : AppCompatActivity(), NavigationView.OnNavigationItemSelecte
             R.id.nav_account -> {
                 intent = Intent(this, AccountSettingsActivity::class.java)
             }
+
             R.id.nav_groups -> {
                 intent = Intent(this, MyGroupsActivity::class.java)
             }
+
             R.id.nav_settings -> {
                 //TODO: Settings
                 return false
@@ -169,6 +411,7 @@ class MainActivity : AppCompatActivity(), NavigationView.OnNavigationItemSelecte
 
                                 }.show()
                         }
+
                         "ShelfFragment" -> {
                             val shelfFragment = fragment as ShelfFragment
                             shelfFragment.removeSelected()

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

@@ -232,6 +232,7 @@ class AbstractProductDAO(private val dbHelper: DBStorageController) {
         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())
@@ -249,6 +250,7 @@ class AbstractProductDAO(private val dbHelper: DBStorageController) {
         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())
@@ -265,7 +267,11 @@ class AbstractProductDAO(private val dbHelper: DBStorageController) {
         )
     }
 
-    fun getSortedListOfAbstractProducts(selectedSort: Int, filterBy: String, filter: Array<String>): List<AbstractProduct> {
+    fun getSortedListOfAbstractProducts(
+        selectedSort: Int,
+        filterBy: String,
+        filter: Array<String>
+    ): List<AbstractProduct> {
 
         val db = dbHelper.readableDatabase
 
@@ -282,10 +288,11 @@ class AbstractProductDAO(private val dbHelper: DBStorageController) {
         )
 
         var orderBy: String = ""
-        when(selectedSort) {
+        when (selectedSort) {
             0 -> {
                 orderBy = "${AbstractProductContract.AbstractProductEntry.PRODUCT_NAME} ASC"
             }
+
             1 -> {
                 orderBy = "${AbstractProductContract.AbstractProductEntry.CATEGORY} ASC"
             }
@@ -299,6 +306,7 @@ class AbstractProductDAO(private val dbHelper: DBStorageController) {
                 selection = "${AbstractProductContract.AbstractProductEntry.CATEGORY} = ?"
                 selectionArgs = filter
             }
+
             "barcodeless" -> {
                 selection = "${AbstractProductContract.AbstractProductEntry.BARCODE} = '' "
                 selectionArgs = null
@@ -306,24 +314,35 @@ class AbstractProductDAO(private val dbHelper: DBStorageController) {
         }
 
 
-        val cursor = db.query(AbstractProductContract.AbstractProductEntry.TABLE_NAME, projection, selection, selectionArgs, null, null, orderBy)
+        val cursor = db.query(
+            AbstractProductContract.AbstractProductEntry.TABLE_NAME,
+            projection,
+            selection,
+            selectionArgs,
+            null,
+            null,
+            orderBy
+        )
 
-        with (cursor) {
+        with(cursor) {
-            while(moveToNext()) {
+            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 productName =
-                val netWeight = getDouble(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NET_WEIGHT))
+                    getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.PRODUCT_NAME))
-                val productImageHash = getString(getColumnIndexOrThrow(AbstractProductContract.AbstractProductEntry.IMAGE_FILENAME))
+                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)
+                val product =
+                    AbstractProduct(productId, barcode, productName, netWeight, productImageHash, category, unit)
 
                 abstractProducts.add(product)
             }
         }
-        return  abstractProducts
+        return abstractProducts
     }
-
 }

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

@@ -5,7 +5,7 @@ import android.content.Context
 import android.provider.BaseColumns
 import org.foxarmy.barcodescannerforemployees.dataclasses.Category
 
-class CategoryDAO (private val dbHelper: DBStorageController) {
+class CategoryDAO(private val dbHelper: DBStorageController) {
     fun eraseCategory(id: Int, context: Context) {
 
         val abstractProductDAO = AbstractProductDAO(dbHelper)
@@ -56,6 +56,7 @@ class CategoryDAO (private val dbHelper: DBStorageController) {
         val categories = mutableListOf<Category>()
 
         val projection = arrayOf(
+            BaseColumns._ID,
             CategoriesContract.CategoryEntry.CATEGORY_NAME
         )
 
@@ -72,7 +73,7 @@ class CategoryDAO (private val dbHelper: DBStorageController) {
         with(cursor) {
             while (moveToNext()) {
                 val category = Category(
-                    getInt(getColumnIndexOrThrow(android.provider.BaseColumns._ID)),
+                    getInt(getColumnIndexOrThrow(BaseColumns._ID)),
                     getString(getColumnIndexOrThrow(CategoriesContract.CategoryEntry.CATEGORY_NAME))
                 )
                 categories.add(category)
@@ -82,15 +83,18 @@ class CategoryDAO (private val dbHelper: DBStorageController) {
         return categories
     }
 
-    fun addCategory(category: Category) {
+    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)
         }
 
-        db.insert(CategoriesContract.CategoryEntry.TABLE_NAME, null, values)
+        val id = db.insert(CategoriesContract.CategoryEntry.TABLE_NAME, null, values)
+
+        return id
     }
 
     fun updateCategory(category: Category) {
@@ -100,6 +104,11 @@ class CategoryDAO (private val dbHelper: DBStorageController) {
         val values = ContentValues().apply {
             put(CategoriesContract.CategoryEntry.CATEGORY_NAME, category.name)
         }
-        db.update(CategoriesContract.CategoryEntry.TABLE_NAME, values, "${BaseColumns._ID} = ?", arrayOf(category.id.toString()))
+        db.update(
+            CategoriesContract.CategoryEntry.TABLE_NAME,
+            values,
+            "${BaseColumns._ID} = ?",
+            arrayOf(category.id.toString())
+        )
     }
 }

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

@@ -13,18 +13,20 @@ class ProductDAO (private val dbHelper: DBStorageController) {
         db.delete(ProductContract.ProductEntry.TABLE_NAME, BaseColumns._ID + "=" + id, null)
     }
 
-    fun insertNewProduct(product: Product) {
+    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)
         }
 
-        db.insert(ProductContract.ProductEntry.TABLE_NAME, null, values)
+        val id = db.insert(ProductContract.ProductEntry.TABLE_NAME, null, values)
+        return id
     }
 
     fun findAmountOfProductsWithExpiryDate(date: Long): Int {
@@ -82,6 +84,7 @@ class ProductDAO (private val dbHelper: DBStorageController) {
         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)
@@ -157,9 +160,7 @@ class ProductDAO (private val dbHelper: DBStorageController) {
 
                 val product = Product(productId, abstractProductId, amount, dateOfProduction, dateOfExpiry)
 
-                if (selectedSort == 2) { //freshness
+                products.add(product)
-                    products.add(product)
-                }
             }
         }
 

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/views/AbstractProductView.kt

@@ -37,13 +37,24 @@ class AbstractProductView: LinearLayout {
     var isProductSelected = false
     private var activity: Activity
 
-    private lateinit var categoryDAO: CategoryDAO
+    private var categoryDAO: CategoryDAO
-    private lateinit var sharedPreferences: SharedPreferences
+    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) {

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

@@ -42,7 +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
@@ -56,9 +56,9 @@ class ProductView: LinearLayout {
     private var strokeColor: Int = 0x000000
     private lateinit var outline: GradientDrawable
 
-    private lateinit var categoryDAO: CategoryDAO
+    private var categoryDAO: CategoryDAO
-    private lateinit var abstractProductDAO: AbstractProductDAO
+    private var abstractProductDAO: AbstractProductDAO
-    private lateinit var sharedPreferences: SharedPreferences
+    private var sharedPreferences: SharedPreferences
 
     constructor(context: Context, a: AttributeSet) : super(context, a) {
         activity = getActivity(context)!!
@@ -71,7 +71,7 @@ class ProductView: LinearLayout {
             EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
         )
 
-        val dbHelper = DBStorageController(context, sharedPreferences.getString("currentGroup", "database")!!)
+        val dbHelper = DBStorageController(context, sharedPreferences.getString("currentGroup", "offline")!!)
         abstractProductDAO = AbstractProductDAO(dbHelper)
         categoryDAO = CategoryDAO(dbHelper)
 
@@ -86,6 +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)