Fix the top app bar logic for top level destinations

app/src/main/kotlin/com/google/samples/apps/nowinandroid/navigation/TopLevelDestination.kt

@@ -22,6 +22,7 @@ import com.google.samples.apps.nowinandroid.R
 import com.google.samples.apps.nowinandroid.core.designsystem.icon.NiaIcons
 import com.google.samples.apps.nowinandroid.feature.bookmarks.navigation.BookmarksRoute
 import com.google.samples.apps.nowinandroid.feature.foryou.navigation.ForYouBaseRoute
+import com.google.samples.apps.nowinandroid.feature.foryou.navigation.ForYouRoute
 import com.google.samples.apps.nowinandroid.feature.interests.navigation.InterestsRoute
 import kotlin.reflect.KClass
 import com.google.samples.apps.nowinandroid.feature.bookmarks.R as bookmarksR
@@ -29,9 +30,18 @@ import com.google.samples.apps.nowinandroid.feature.foryou.R as forYouR
 import com.google.samples.apps.nowinandroid.feature.search.R as searchR
 
 /**
- * Type for the top level destinations in the application. Each of these destinations
- * can contain one or more screens (based on the window size). Navigation from one screen to the
- * next within a single destination will be handled directly in composables.
+ * Type for the top level destinations in the application. Contains metadata about the destination
+ * that is used in the top app bar and common navigation UI.
+ *
+ * @param selectedIcon The icon to be displayed in the navigation UI when this destination is
+ * selected.
+ * @param unselectedIcon The icon to be displayed in the navigation UI when this destination is
+ * not selected.
+ * @param iconTextId Text that to be displayed in the navigation UI.
+ * @param titleTextId Text that is displayed on the top app bar.
+ * @param route The route to use when navigating to this destination.
+ * @param baseRoute The highest ancestor of this destination. Defaults to [route], meaning that
+ * there is a single destination in that section of the app (no nested destinations).
  */
 enum class TopLevelDestination(
     val selectedIcon: ImageVector,
@@ -39,13 +49,15 @@ enum class TopLevelDestination(
     @StringRes val iconTextId: Int,
     @StringRes val titleTextId: Int,
     val route: KClass<*>,
+    val baseRoute: KClass<*> = route,
 ) {
     FOR_YOU(
         selectedIcon = NiaIcons.Upcoming,
         unselectedIcon = NiaIcons.UpcomingBorder,
         iconTextId = forYouR.string.feature_foryou_title,
         titleTextId = R.string.app_name,
-        route = ForYouBaseRoute::class,
+        route = ForYouRoute::class,
+        baseRoute = ForYouBaseRoute::class,
     ),
     BOOKMARKS(
         selectedIcon = NiaIcons.Bookmarks,

app/src/main/kotlin/com/google/samples/apps/nowinandroid/ui/NiaApp.kt

@@ -152,7 +152,7 @@ internal fun NiaApp(
             appState.topLevelDestinations.forEach { destination ->
                 val hasUnread = unreadDestinations.contains(destination)
                 val selected = currentDestination
-                    .isRouteInHierarchy(destination.route)
+                    .isRouteInHierarchy(destination.baseRoute)
                 item(
                     selected = selected,
                     onClick = { appState.navigateToTopLevelDestination(destination) },

app/src/main/kotlin/com/google/samples/apps/nowinandroid/ui/NiaAppState.kt

@@ -90,7 +90,7 @@ class NiaAppState(
     val currentTopLevelDestination: TopLevelDestination?
         @Composable get() {
             return TopLevelDestination.entries.firstOrNull { topLevelDestination ->
-                currentDestination?.hasRoute(route = topLevelDestination.route) ?: false
+                currentDestination?.hasRoute(route = topLevelDestination.route) == true
             }
         }