fix back navigation on preview screen in different cases

app/src/main/java/com/isidroid/c23/MainActivity.kt

@@ -29,6 +29,7 @@ import com.isidroid.c23.ui.navigation.routeHome
 import com.isidroid.c23.ui.theme.AppTheme
 import com.isidroid.core.ext.navigateSingleTopTo
 import com.isidroid.core.ext.printCurrentDestination
+import com.isidroid.core.ext.printNavigationStack
 import com.isidroid.utils.extractUris
 import dagger.hilt.android.AndroidEntryPoint
 
@@ -64,7 +65,7 @@ fun ComposeApp() {
             navController.navigateSingleTopTo(routeHome(uris = uris.joinToString()))
     }
 
-    LaunchedEffect(Unit) { navController.printCurrentDestination() }
+    LaunchedEffect(Unit) { navController.printNavigationStack() }
 
     val surfaceModifier = with(Modifier) {
         if (!isEdgeToEdge)

app/src/main/java/com/isidroid/c23/ui/_component/BackCloseComponent.kt

+package com.isidroid.c23.ui._component
+
+import android.widget.Toast
+import androidx.activity.ComponentActivity
+import androidx.activity.compose.BackHandler
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.platform.LocalContext
+import androidx.navigation.NavController
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
+
+@Composable
+internal fun BackCloseComponent(navController: NavController) {
+    var showExitApp by remember { mutableStateOf(false) }
+    val activity = LocalContext.current as? ComponentActivity
+    val scope = rememberCoroutineScope()
+
+    LaunchedEffect(showExitApp) {
+        if (showExitApp)
+            scope.launch(Dispatchers.Default) {
+                delay(2000)
+                showExitApp = false
+            }
+    }
+
+    BackHandler {
+        when {
+            navController.previousBackStackEntry != null -> navController.popBackStack()
+            showExitApp -> activity?.finish()
+            else -> {
+                showExitApp = true
+                Toast.makeText(activity, "Tap back again to close the app", Toast.LENGTH_LONG).show()
+            }
+        }
+    }
+}
\ No newline at end of file

app/src/main/java/com/isidroid/c23/ui/navigation/destinations/ContentScreenDestination.kt

@@ -3,18 +3,20 @@ package com.isidroid.c23.ui.navigation.destinations
 import androidx.compose.runtime.Composable
 import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.navigation.NavHostController
+import com.isidroid.c23.ui._component.BackCloseComponent
 import com.isidroid.c23.ui.navigation.routeMap
 import com.isidroid.c23.ui.navigation.routePrintJobs
 import com.isidroid.c23.ui.navigation.routeRenderPreview
 import com.isidroid.c23.ui.screen.content.ContentContract
 import com.isidroid.c23.ui.screen.content.ContentScreen
 import com.isidroid.c23.ui.screen.content.ContentViewModel
-import com.isidroid.core.ext.navigateSingleTopTo
 
 @Composable
 fun ContentScreenDestination(navController: NavHostController) {
     val viewModel: ContentViewModel = hiltViewModel()
 
+    BackCloseComponent(navController)
+
     ContentScreen(
         state = viewModel.viewState,
         effectFlow = viewModel.effect,
@@ -22,7 +24,7 @@ fun ContentScreenDestination(navController: NavHostController) {
         onNavigationRequested = { effect ->
             when (effect) {
                 is ContentContract.Effect.Navigation.ToRenderPreview -> navController.navigate(routeRenderPreview(uris = effect.uris))
-                is ContentContract.Effect.Navigation.ToMap -> navController.navigateSingleTopTo(routeMap(effect.lat?.toString(), effect.lng?.toString(), effect.spotId))
+                is ContentContract.Effect.Navigation.ToMap -> navController.navigate(routeMap(effect.lat?.toString(), effect.lng?.toString(), effect.spotId))
                 ContentContract.Effect.Navigation.ToBack -> navController.popBackStack()
                 ContentContract.Effect.Navigation.ToPrintJobList -> navController.navigate(routePrintJobs())
             }

app/src/main/java/com/isidroid/c23/ui/navigation/destinations/RenderScreenDestination.kt

@@ -3,12 +3,14 @@ package com.isidroid.c23.ui.navigation.destinations
 import androidx.compose.runtime.Composable
 import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.navigation.NavController
+import com.isidroid.c23.ui._component.BackCloseComponent
 import com.isidroid.c23.ui.navigation.routeMap
 import com.isidroid.c23.ui.navigation.routeSelectContent
 import com.isidroid.c23.ui.screen.render_preview.RenderContract
 import com.isidroid.c23.ui.screen.render_preview.RenderPreviewScreen
 import com.isidroid.c23.ui.screen.render_preview.RenderViewModel
 import com.isidroid.core.ext.navigateSingleTopTo
+import timber.log.Timber
 
 @Composable
 fun RenderScreenDestination(navController: NavController) {
@@ -21,7 +23,13 @@ fun RenderScreenDestination(navController: NavController) {
         onEventSent = { event -> viewModel.setEvent(event) },
         onNavigationRequested = { effect ->
             when (effect) {
-                RenderContract.Effect.Navigation.ToBack -> navController.popBackStack()
+                RenderContract.Effect.Navigation.ToBack -> {
+                    if (navController.previousBackStackEntry != null)
+                        navController.popBackStack()
+                    else
+                        navController.navigateSingleTopTo(routeSelectContent())
+                }
+
                 RenderContract.Effect.Navigation.ToMap -> navController.navigate(routeMap())
                 RenderContract.Effect.Navigation.ToSelectContent -> navController.navigateSingleTopTo(routeSelectContent())
             }

app/src/main/java/com/isidroid/c23/ui/screen/content/ContentScreen.kt

@@ -71,10 +71,6 @@ fun ContentScreen(
         onEventSent(ContentContract.Event.CopyRenderedFilesToPublicFolder(it))
     }
 
-    BackHandler {
-        onEventSent(ContentContract.Event.GoBack)
-    }
-
     LaunchedEffect(state.value.galleryHash) { if (state.value.galleryHash != null) launcher.launch("image/*") }
     LaunchedEffect(state.value.documentHash) { if (state.value.documentHash != null) launcher.launch("application/pdf") }
     LaunchedEffect(state.value.wordHash) { if (state.value.wordHash != null) launcher.launch("application/msword") }

core/core/src/main/java/com/isidroid/core/ext/ExtNavigation.kt

 package com.isidroid.core.ext
 
+import android.annotation.SuppressLint
+import androidx.core.net.toUri
 import androidx.navigation.NavController
 import androidx.navigation.NavGraph.Companion.findStartDestination
 import androidx.navigation.NavHostController
@@ -71,4 +73,10 @@ suspend fun NavHostController?.printCurrentDestination(
     }.collect()
 }
 
-
+@SuppressLint("RestrictedApi")
+suspend fun NavHostController.printNavigationStack(tag: String = "navigation_graph") {
+    currentBackStack.collect { list ->
+        val backstack = list.mapNotNull { navBackStackEntry -> navBackStackEntry.destination.route?.toUri()?.path }.joinToString()
+        Timber.tag(tag).i(backstack)
+    }
+}
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