added ability to use application offline

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

@@ -104,6 +104,15 @@ class LoginActivity : AppCompatActivity() {
                 }
             }
         }
+
+        binding.offlineButton.setOnClickListener {
+            sharedPreferences.edit().putString("currentGroup", "offline").apply()
+            sharedPreferences.edit().putStringSet("groups", setOf("offline")).apply()
+
+            val intent = Intent(this, MainActivity::class.java)
+            startActivity(intent)
+            finish()
+        }
     }
 
     private fun fillUpLanguagesSpinner() {

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

@@ -6,6 +6,7 @@ import android.content.Intent
 import android.os.Bundle
 import android.view.Menu
 import android.view.MenuItem
+import android.widget.Toast
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.appcompat.app.ActionBarDrawerToggle
 import androidx.appcompat.app.AlertDialog
@@ -108,8 +109,8 @@ class MainActivity : AppCompatActivity(), NavigationView.OnNavigationItemSelecte
         }
         val net = Net()
         net.server = sharedPreferences.getString("server", "")!!
-
+        val currentGroup = sharedPreferences.getString("currentGroup", "offline")!!
-        if (!net.serverIsAvailable(this)) {
+        if ( currentGroup != "offline" && !net.serverIsAvailable(this)) {
             noInternetConnectionAvailableNotification(this)
         } else {
             synchronize()
@@ -393,16 +394,35 @@ class MainActivity : AppCompatActivity(), NavigationView.OnNavigationItemSelecte
         return true
     }
 
+    private fun isOffline(): Boolean {
+        val sharedPreferences = EncryptedSharedPreferences.create(
+            "sensitive",
+            MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),
+            applicationContext,
+            EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+            EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        )
+        return sharedPreferences.getString("currentGroup", "") == "offline"
+    }
+
     override fun onNavigationItemSelected(item: MenuItem): Boolean {
         lateinit var intent: Intent
         when (item.itemId) {
             R.id.nav_account -> {
+                if (isOffline()) {
+                    Toast.makeText(this, getString(R.string.online_only_feature), Toast.LENGTH_SHORT).show()
+                    return false
+                }
                 intent = Intent(this, AccountSettingsActivity::class.java)
                 settingsActivityLauncher.launch(intent)
                 return true
             }
 
             R.id.nav_groups -> {
+                if (isOffline()) {
+                    Toast.makeText(this, getString(R.string.online_only_feature), Toast.LENGTH_SHORT).show()
+                    return false
+                }
                 intent = Intent(this, MyGroupsActivity::class.java)
             }
 

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

@@ -24,11 +24,11 @@ class NavigatorActivity : Activity() {
 
         var intent = Intent(this, MainActivity::class.java)
 
-        if (!isInGroup()) {
+        if (!isInGroup() && !isOffline()) {
             intent = Intent(this, GroupActivity::class.java)
         }
 
-        if (!isAuthenticated()) {
+        if (!isAuthenticated() && !isOffline()) {
             intent = Intent(this, LoginActivity::class.java);
         }
 
@@ -36,6 +36,10 @@ class NavigatorActivity : Activity() {
         finish();
     }
 
+    private fun isOffline(): Boolean {
+        return sharedPreferences.getString("currentGroup", "")!! == "offline"
+    }
+
     private fun isAuthenticated(): Boolean {
         return sharedPreferences.getString("token", "") != ""
     }

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

@@ -37,17 +37,23 @@ class SettingsActivity : AppCompatActivity() {
         net.language = sharedPreferences.getString("language", "")!!
         net.server = sharedPreferences.getString("server", "")!!
 
+        binding = ActivitySettingsBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+
+        setUpImageCompressionSeekBar()
+
+
+        if (isOffline()) {
+            binding.currentGroupSetting.visibility = View.GONE
+        } else {
             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()
@@ -62,14 +68,16 @@ class SettingsActivity : AppCompatActivity() {
         }
     }
 
+    private fun isOffline(): Boolean {
+        return sharedPreferences.getString("currentGroup", "offline") == "offline"
+    }
+
     private fun setUpImageCompressionSeekBar() {
         val compressionFactor = sharedPreferences.getInt("imageCompression", 1)
         binding.imageCompressionFactorSeekBar.progress = compressionFactor - 1
     }
 
     private fun fillUpCurrentGroupSpinner() {
-
-
         if (currentGroup == "offline") {
             binding.currentGroupSetting.visibility = View.GONE
         }

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

@@ -117,6 +117,7 @@
     <string name="no_internet_connection">No internet connection available. Please, connect to a network.</string>
     <string name="ok">Ok</string>
     <string name="logout">Log out</string>
+    <string name="online_only_feature">This feature is online only</string>
     <string-array name="languages">
         <item>en-US</item>
         <item>ru-RU</item>

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

@@ -115,6 +115,7 @@
     <string name="no_internet_connection">No internet connection available. Please, connect to a network.</string>
     <string name="ok">Ok</string>
     <string name="logout">Log out</string>
+    <string name="online_only_feature">This feature is online only</string>
     <string-array name="languages">
         <item>en-US</item>
         <item>ru-RU</item>