Option to enable exit confirmation

app/src/main/java/org/koitharu/kotatsu/core/prefs/AppSettings.kt

@@ -130,6 +130,9 @@ class AppSettings(context: Context) {
 		get() = prefs.getBoolean(KEY_PROTECT_APP_BIOMETRIC, true)
 		set(value) = prefs.edit { putBoolean(KEY_PROTECT_APP_BIOMETRIC, value) }
 
+	val isExitConfirmationEnabled: Boolean
+		get() = prefs.getBoolean(KEY_EXIT_CONFIRM, false)
+
 	var sourcesOrder: List<String>
 		get() = prefs.getString(KEY_SOURCES_ORDER, null)
 			?.split('|')
@@ -306,6 +309,7 @@ class AppSettings(context: Context) {
 		const val KEY_DOWNLOADS_SLOWDOWN = "downloads_slowdown"
 		const val KEY_ALL_FAVOURITES_VISIBLE = "all_favourites_visible"
 		const val KEY_DOH = "doh"
+		const val KEY_EXIT_CONFIRM = "exit_confirm"
 
 		// About
 		const val KEY_APP_UPDATE = "app_update"

app/src/main/java/org/koitharu/kotatsu/main/ui/ExitCallback.kt

@@ -0,0 +1,54 @@
+package org.koitharu.kotatsu.main.ui
+
+import android.view.View
+import androidx.activity.ComponentActivity
+import androidx.activity.OnBackPressedCallback
+import androidx.lifecycle.lifecycleScope
+import com.google.android.material.snackbar.Snackbar
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.flowOn
+import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.onEach
+import kotlinx.coroutines.launch
+import org.koin.android.ext.android.get
+import org.koitharu.kotatsu.R
+import org.koitharu.kotatsu.core.prefs.AppSettings
+import org.koitharu.kotatsu.core.prefs.observeAsFlow
+
+class ExitCallback(
+	private val activity: ComponentActivity,
+	private val snackbarHost: View,
+) : OnBackPressedCallback(false) {
+
+	private var job: Job? = null
+
+	init {
+		observeSettings()
+	}
+
+	override fun handleOnBackPressed() {
+		job?.cancel()
+		job = activity.lifecycleScope.launch {
+			resetExitConfirmation()
+		}
+	}
+
+	private suspend fun resetExitConfirmation() {
+		isEnabled = false
+		val snackbar = Snackbar.make(snackbarHost, R.string.confirm_exit, Snackbar.LENGTH_INDEFINITE)
+		snackbar.show()
+		delay(2000)
+		snackbar.dismiss()
+		isEnabled = true
+	}
+
+	private fun observeSettings() {
+		activity.get<AppSettings>()
+			.observeAsFlow(AppSettings.KEY_EXIT_CONFIRM) { isExitConfirmationEnabled }
+			.flowOn(Dispatchers.Default)
+			.onEach { isEnabled = it }
+			.launchIn(activity.lifecycleScope)
+	}
+}

app/src/main/java/org/koitharu/kotatsu/main/ui/MainActivity.kt

@@ -4,7 +4,6 @@ import android.os.Bundle
 import android.view.MenuItem
 import android.view.View
 import android.view.ViewGroup.MarginLayoutParams
-import android.widget.Toast
 import androidx.activity.result.ActivityResultCallback
 import androidx.annotation.IdRes
 import androidx.appcompat.view.ActionMode
@@ -21,8 +20,6 @@ import com.google.android.material.appbar.AppBarLayout.LayoutParams.*
 import com.google.android.material.navigation.NavigationBarView
 import com.google.android.material.snackbar.Snackbar
 import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.delay
-import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 import org.koin.android.ext.android.get
 import org.koin.androidx.viewmodel.ext.android.viewModel
@@ -63,8 +60,6 @@ class MainActivity :
 	View.OnFocusChangeListener,
 	SearchSuggestionListener, NavigationBarView.OnItemSelectedListener {
 
-	private var isConfirmingExit: Boolean = false
-
 	private val viewModel by viewModel<MainViewModel>()
 	private val searchSuggestionViewModel by viewModel<SearchSuggestionViewModel>()
 	private val voiceInputLauncher = registerForActivityResult(VoiceInputContract(), VoiceInputCallback())
@@ -99,6 +94,7 @@ class MainActivity :
 		binding.navRail?.headerView?.setOnClickListener(this)
 		binding.searchView.isVoiceSearchEnabled = voiceInputLauncher.resolve(this, null) != null
 
+		onBackPressedDispatcher.addCallback(ExitCallback(this, binding.container))
 		supportFragmentManager.findFragmentByTag(TAG_PRIMARY)?.let {
 			if (it is LibraryFragment) binding.fab?.show() else binding.fab?.hide()
 		} ?: onNavigationItemSelected(navBar.selectedItemId)
@@ -136,7 +132,6 @@ class MainActivity :
 				setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE)
 				runOnCommit { onSearchClosed() }
 			}
-			shouldHandleExitConfirmation() -> lifecycleScope.launch { resetExitConfirmation() }
 			else -> super.onBackPressed()
 		}
 	}
@@ -153,19 +148,6 @@ class MainActivity :
 		return super.onOptionsItemSelected(item)
 	}
 
-	private suspend fun resetExitConfirmation() {
-		isConfirmingExit = true
-		val toast = Toast.makeText(this, R.string.confirm_exit, Toast.LENGTH_LONG)
-		toast.show()
-		delay(2000)
-		toast.cancel()
-		isConfirmingExit = false
-	}
-
-	private fun shouldHandleExitConfirmation(): Boolean {
-		return !isConfirmingExit
-	}
-
 	override fun onClick(v: View) {
 		when (v.id) {
 			R.id.fab -> viewModel.openLastReader()

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

@@ -337,5 +337,7 @@
 	<string name="changelog">Changelog</string>
 	<string name="explore">Explore</string>
 	<string name="tools">Tools</string>
-	<string name="confirm_exit">Press back again to exit</string>
+	<string name="confirm_exit">Press "Back" again to exit</string>
+	<string name="exit_confirmation_summary">Press "Back" twice to exit the app</string>
+	<string name="exit_confirmation">Exit confirmation</string>
 </resources>

app/src/main/res/xml/pref_appearance.xml

@@ -43,11 +43,17 @@
 		android:valueTo="150"
 		app:defaultValue="100" />
 
+	<SwitchPreferenceCompat
+		android:defaultValue="false"
+		android:key="exit_confirm"
+		android:summary="@string/exit_confirmation_summary"
+		android:title="@string/exit_confirmation"
+		app:allowDividerAbove="true" />
+
 	<SwitchPreferenceCompat
 		android:key="protect_app"
 		android:persistent="false"
 		android:summary="@string/protect_application_summary"
-		android:title="@string/protect_application"
-		app:allowDividerAbove="true" />
+		android:title="@string/protect_application" />
 
 </PreferenceScreen>