feat: add online status handling to navigation and UI components

app/src/main/java/hu/bbara/purefin/ui/screen/AppBottomBar.kt

@@ -13,9 +13,11 @@ import androidx.compose.runtime.Composable
 @Composable
 fun AppBottomBar(
     selectedTab: Int,
+    isOnline: Boolean,
     onTabSelected: (Int) -> Unit
 ) {
     NavigationBar {
+        if (isOnline) {
             NavigationBarItem(
                 selected = selectedTab == 0,
                 onClick = { onTabSelected(0) },
@@ -28,8 +30,9 @@ fun AppBottomBar(
                 icon = { Icon(Icons.Outlined.Collections, contentDescription = "Libraries") },
                 label = { Text("Libraries") }
             )
+        }
         NavigationBarItem(
-            selected = selectedTab == 2,
+            selected = !isOnline || selectedTab == 2,
             onClick = { onTabSelected(2) },
             icon = { Icon(Icons.Outlined.Download, contentDescription = "Downloads") },
             label = { Text("Downloads") }

app/src/main/java/hu/bbara/purefin/ui/screen/AppScreen.kt

@@ -44,6 +44,7 @@ fun AppScreen(
     val continueWatching by viewModel.continueWatching.collectAsState()
     val nextUp by viewModel.nextUp.collectAsState()
     val isRefreshing by viewModel.isRefreshing.collectAsState()
+    val isOnline by viewModel.isOnline.collectAsState()
     val isCheckingForUpdates by updateViewModel.isCheckingForUpdates.collectAsState()
     val availableUpdate by updateViewModel.availableUpdate.collectAsState()
     val navigationManager = LocalNavigationManager.current
@@ -54,6 +55,13 @@ fun AppScreen(
     val currentRoute = backStack.lastOrNull() ?: AppTabRoute.Home
     val selectedTab = currentRoute.toTabIndex()
 
+    LaunchedEffect(isOnline, currentRoute, backStack) {
+        if (!isOnline && currentRoute != AppTabRoute.Downloads) {
+            backStack.clear()
+            backStack.add(AppTabRoute.Downloads)
+        }
+    }
+
     LifecycleResumeEffect(Unit) {
         viewModel.onResumed()
         onPauseOrDispose { }
@@ -69,9 +77,9 @@ fun AppScreen(
         }
     }
 
-    val onTabSelected = remember(backStack) {
+    val onTabSelected = remember(backStack, isOnline) {
         { selectedIndex: Int ->
-            val route = selectedIndex.toAppTabRoute()
+            val route = if (isOnline) selectedIndex.toAppTabRoute() else AppTabRoute.Downloads
             if (backStack.lastOrNull() != route) {
                 backStack.add(route)
             }
@@ -104,6 +112,7 @@ fun AppScreen(
                 onSearchClick = viewModel::openSearch,
                 snackbarHostState = snackbarHostState,
                 selectedTab = selectedTab,
+                isOnline = isOnline,
                 onTabSelected = onTabSelected,
                 modifier = Modifier.fillMaxSize()
             )
@@ -114,6 +123,7 @@ fun AppScreen(
                 onLibrarySelected = { item -> viewModel.onLibrarySelected(item.id, item.name) },
                 onSearchClick = viewModel::openSearch,
                 selectedTab = selectedTab,
+                isOnline = isOnline,
                 onTabSelected = onTabSelected,
                 modifier = Modifier.fillMaxSize()
             )
@@ -121,6 +131,7 @@ fun AppScreen(
         entry<AppTabRoute.Downloads>(metadata = appTabMetadata(AppTabRoute.Downloads)) {
             DownloadsScreen(
                 selectedTab = selectedTab,
+                isOnline = isOnline,
                 onTabSelected = onTabSelected,
                 modifier = Modifier.fillMaxSize()
             )

app/src/main/java/hu/bbara/purefin/ui/screen/download/DownloadsScreen.kt

@@ -12,6 +12,7 @@ import hu.bbara.purefin.ui.screen.AppBottomBar
 @Composable
 fun DownloadsScreen(
     selectedTab: Int,
+    isOnline: Boolean,
     onTabSelected: (Int) -> Unit,
     modifier: Modifier = Modifier
 ) {
@@ -22,6 +23,7 @@ fun DownloadsScreen(
         bottomBar = {
             AppBottomBar(
                 selectedTab = selectedTab,
+                isOnline = isOnline,
                 onTabSelected = onTabSelected
             )
         }

app/src/main/java/hu/bbara/purefin/ui/screen/home/HomeScreen.kt

@@ -35,6 +35,7 @@ fun HomeScreen(
     onSearchClick: () -> Unit,
     snackbarHostState: SnackbarHostState,
     selectedTab: Int,
+    isOnline: Boolean,
     onTabSelected: (Int) -> Unit,
     modifier: Modifier = Modifier
 ) {
@@ -57,6 +58,7 @@ fun HomeScreen(
         bottomBar = {
             AppBottomBar(
                 selectedTab = selectedTab,
+                isOnline = isOnline,
                 onTabSelected = onTabSelected
             )
         }

app/src/main/java/hu/bbara/purefin/ui/screen/libraries/LibrariesScreen.kt

@@ -17,6 +17,7 @@ fun LibrariesScreen(
     onLibrarySelected: (LibraryUiModel) -> Unit,
     onSearchClick: () -> Unit,
     selectedTab: Int,
+    isOnline: Boolean,
     onTabSelected: (Int) -> Unit,
     modifier: Modifier = Modifier
 ) {
@@ -32,6 +33,7 @@ fun LibrariesScreen(
         bottomBar = {
             AppBottomBar(
                 selectedTab = selectedTab,
+                isOnline = isOnline,
                 onTabSelected = onTabSelected
             )
         }

core/src/main/java/hu/bbara/purefin/core/feature/browse/home/AppViewModel.kt

@@ -5,6 +5,7 @@ import androidx.lifecycle.viewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
 import hu.bbara.purefin.core.data.HomeRepository
 import hu.bbara.purefin.core.data.LocalMediaRepository
+import hu.bbara.purefin.core.data.NetworkMonitor
 import hu.bbara.purefin.core.data.UserSessionRepository
 import hu.bbara.purefin.core.download.MediaDownloadController
 import hu.bbara.purefin.core.jellyfin.JellyfinMediaMetadataUpdater
@@ -40,11 +41,19 @@ class AppViewModel @Inject constructor(
     private val jellyfinMediaMetadataUpdater: JellyfinMediaMetadataUpdater,
     private val navigationManager: NavigationManager,
     private val mediaDownloadManager: MediaDownloadController,
+    networkMonitor: NetworkMonitor,
 ) : ViewModel() {
 
     private val _isRefreshing = MutableStateFlow(false)
     val isRefreshing: StateFlow<Boolean> = _isRefreshing.asStateFlow()
 
+    val isOnline: StateFlow<Boolean> = networkMonitor.isOnline
+        .stateIn(
+            viewModelScope,
+            SharingStarted.Eagerly,
+            false
+        )
+
     val serverUrl: StateFlow<String> = userSessionRepository.serverUrl
         .stateIn(
             viewModelScope,