[WIP] Draft Nav3 migration (from Don)

app/build.gradle.kts

@@ -72,12 +72,14 @@ android {
 dependencies {
     implementation(projects.feature.interests)
     implementation(projects.feature.foryou)
-    implementation(projects.feature.bookmarks)
+    implementation(projects.feature.bookmarks.api)
+    implementation(projects.feature.bookmarks.impl)
     implementation(projects.feature.topic)
     implementation(projects.feature.search)
     implementation(projects.feature.settings)
 
     implementation(projects.core.common)
+    implementation(projects.core.navigation)
     implementation(projects.core.ui)
     implementation(projects.core.designsystem)
     implementation(projects.core.data)

app/src/androidTest/kotlin/com/google/samples/apps/nowinandroid/ui/NavigationTest.kt

@@ -47,7 +47,7 @@ import org.junit.Before
 import org.junit.Rule
 import org.junit.Test
 import javax.inject.Inject
-import com.google.samples.apps.nowinandroid.feature.bookmarks.R as BookmarksR
+import com.google.samples.apps.nowinandroid.feature.bookmarks.impl.R as BookmarksR
 import com.google.samples.apps.nowinandroid.feature.foryou.R as FeatureForyouR
 import com.google.samples.apps.nowinandroid.feature.search.R as FeatureSearchR
 import com.google.samples.apps.nowinandroid.feature.settings.R as SettingsR

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

@@ -19,12 +19,20 @@ package com.google.samples.apps.nowinandroid.navigation
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
 import androidx.navigation.compose.NavHost
-import com.google.samples.apps.nowinandroid.feature.bookmarks.navigation.bookmarksScreen
+import androidx.navigation.compose.composable
+import androidx.navigation.compose.navigation
+import androidx.navigation3.runtime.NavEntry
+import androidx.navigation3.runtime.entryProvider
+import androidx.navigation3.ui.NavDisplay
+import com.google.samples.apps.nowinandroid.feature.bookmarks.api.navigation.BookmarksRoute
+import com.google.samples.apps.nowinandroid.feature.bookmarks.impl.navigation.bookmarksScreen
 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.foryou.navigation.forYouSection
-import com.google.samples.apps.nowinandroid.feature.interests.navigation.navigateToInterests
+import com.google.samples.apps.nowinandroid.feature.interests.navigation.InterestsRoute
+import com.google.samples.apps.nowinandroid.feature.search.navigation.SearchRoute
 import com.google.samples.apps.nowinandroid.feature.search.navigation.searchScreen
-import com.google.samples.apps.nowinandroid.feature.topic.navigation.navigateToTopic
+import com.google.samples.apps.nowinandroid.feature.topic.navigation.TopicRoute
 import com.google.samples.apps.nowinandroid.feature.topic.navigation.topicScreen
 import com.google.samples.apps.nowinandroid.navigation.TopLevelDestination.INTERESTS
 import com.google.samples.apps.nowinandroid.ui.NiaAppState
@@ -44,29 +52,57 @@ fun NiaNavHost(
     modifier: Modifier = Modifier,
 ) {
     val navController = appState.navController
-    NavHost(
-        navController = navController,
-        startDestination = ForYouBaseRoute,
-        modifier = modifier,
-    ) {
-        forYouSection(
-            onTopicClick = navController::navigateToTopic,
+    val nav3Navigator = appState.nav3Navigator
+    NavDisplay(
+        backStack = nav3Navigator.backStack,
+        onBack = { nav3Navigator.goBack() },
+        entryProvider = entryProvider(
+            fallback = { key ->
+                println("$key not found, using fallback entry")
+                NavEntry(key = key) {
+                    NavHost(
+                        navController = navController,
+                        startDestination = ForYouBaseRoute,
+                        modifier = modifier,
+                    ) {
+                        navigation<ForYouBaseRoute>(startDestination = ForYouRoute) {
+                            composable<ForYouRoute> {}
+                            composable<TopicRoute> {}
+                        }
+                        composable<ForYouRoute> {}
+                        composable<BookmarksRoute> {}
+                        composable<SearchRoute> {}
+                        composable<InterestsRoute>{}
+                    }
+                }
+            },
         ) {
+            forYouSection(
+                onTopicClick = {
+                    nav3Navigator.goTo(route = TopicRoute(it))
+                },
+            )
+            bookmarksScreen(
+                onTopicClick = { it: String ->
+                    nav3Navigator.goTo(route = InterestsRoute(it))
+                },
+                onShowSnackbar = onShowSnackbar
+            )
             topicScreen(
                 showBackButton = true,
+                onBackClick = { nav3Navigator.goBack() },
+                onTopicClick = {
+                    nav3Navigator.goTo(route = TopicRoute(it))
+                },
+            )
+            searchScreen(
                 onBackClick = navController::popBackStack,
-                onTopicClick = navController::navigateToTopic,
+                onInterestsClick = { appState.navigateToTopLevelDestination(INTERESTS) },
+                onTopicClick = {
+                    nav3Navigator.goTo(route = InterestsRoute(it))
+                },
             )
-        }
-        bookmarksScreen(
-            onTopicClick = navController::navigateToInterests,
-            onShowSnackbar = onShowSnackbar,
-        )
-        searchScreen(
-            onBackClick = navController::popBackStack,
-            onInterestsClick = { appState.navigateToTopLevelDestination(INTERESTS) },
-            onTopicClick = navController::navigateToInterests,
-        )
-        interestsListDetailScreen()
-    }
+            interestsListDetailScreen()
+        },
+    )
 }

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

@@ -20,12 +20,12 @@ import androidx.annotation.StringRes
 import androidx.compose.ui.graphics.vector.ImageVector
 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.bookmarks.api.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
+import com.google.samples.apps.nowinandroid.feature.bookmarks.impl.R as bookmarksR
 import com.google.samples.apps.nowinandroid.feature.foryou.R as forYouR
 import com.google.samples.apps.nowinandroid.feature.search.R as searchR
 

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

@@ -136,6 +136,9 @@ internal fun NiaApp(
 ) {
     val unreadDestinations by appState.topLevelDestinationsWithUnreadResources
         .collectAsStateWithLifecycle()
+
+    // TODO: This is only used to determine whether the bottom nav item is selected
+    // this can be improved by just getting
     val currentDestination = appState.currentDestination
 
     if (showSettingsDialog) {
@@ -144,6 +147,10 @@ internal fun NiaApp(
         )
     }
 
+    // TODO: figure out how have the existing navigation bar support both old and new routes
+    //  essentially we need a migration path from what's below to the common UI recipe
+    //  this probably comes down to how the back stack is modelled.
+
     NiaNavigationSuiteScaffold(
         navigationSuiteItems = {
             appState.topLevelDestinations.forEach { destination ->
@@ -167,9 +174,9 @@ internal fun NiaApp(
                     },
                     label = { Text(stringResource(destination.iconTextId)) },
                     modifier =
-                    Modifier
-                        .testTag("NiaNavItem")
-                        .then(if (hasUnread) Modifier.notificationDot() else Modifier),
+                        Modifier
+                            .testTag("NiaNavItem")
+                            .then(if (hasUnread) Modifier.notificationDot() else Modifier),
                 )
             }
         },

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

@@ -19,35 +19,44 @@ package com.google.samples.apps.nowinandroid.ui
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.Stable
 import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.mutableStateListOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
 import androidx.navigation.NavController
 import androidx.navigation.NavDestination
 import androidx.navigation.NavDestination.Companion.hasRoute
+import androidx.navigation.NavGraph
 import androidx.navigation.NavGraph.Companion.findStartDestination
 import androidx.navigation.NavHostController
+import androidx.navigation.NavOptions
 import androidx.navigation.compose.rememberNavController
 import androidx.navigation.navOptions
+import androidx.navigation.toRoute
 import androidx.tracing.trace
 import com.google.samples.apps.nowinandroid.core.data.repository.UserNewsResourceRepository
 import com.google.samples.apps.nowinandroid.core.data.util.NetworkMonitor
 import com.google.samples.apps.nowinandroid.core.data.util.TimeZoneMonitor
 import com.google.samples.apps.nowinandroid.core.ui.TrackDisposableJank
-import com.google.samples.apps.nowinandroid.feature.bookmarks.navigation.navigateToBookmarks
-import com.google.samples.apps.nowinandroid.feature.foryou.navigation.navigateToForYou
-import com.google.samples.apps.nowinandroid.feature.interests.navigation.navigateToInterests
+import com.google.samples.apps.nowinandroid.feature.bookmarks.api.navigation.BookmarksRoute
+import com.google.samples.apps.nowinandroid.feature.foryou.navigation.ForYouRoute
+import com.google.samples.apps.nowinandroid.feature.interests.navigation.InterestsRoute
+import com.google.samples.apps.nowinandroid.feature.search.navigation.SearchRoute
 import com.google.samples.apps.nowinandroid.feature.search.navigation.navigateToSearch
+import com.google.samples.apps.nowinandroid.feature.topic.navigation.TopicRoute
 import com.google.samples.apps.nowinandroid.navigation.TopLevelDestination
 import com.google.samples.apps.nowinandroid.navigation.TopLevelDestination.BOOKMARKS
 import com.google.samples.apps.nowinandroid.navigation.TopLevelDestination.FOR_YOU
 import com.google.samples.apps.nowinandroid.navigation.TopLevelDestination.INTERESTS
 import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.stateIn
+import kotlinx.coroutines.launch
 import kotlinx.datetime.TimeZone
 
 @Composable
@@ -59,6 +68,11 @@ fun rememberNiaAppState(
     navController: NavHostController = rememberNavController(),
 ): NiaAppState {
     NavigationTrackingSideEffect(navController)
+
+    val nav3Navigator = remember(navController) {
+        Nav3NavigatorSimple(navController)
+    }
+
     return remember(
         navController,
         coroutineScope,
@@ -68,6 +82,7 @@ fun rememberNiaAppState(
     ) {
         NiaAppState(
             navController = navController,
+            nav3Navigator = nav3Navigator,
             coroutineScope = coroutineScope,
             networkMonitor = networkMonitor,
             userNewsResourceRepository = userNewsResourceRepository,
@@ -79,6 +94,7 @@ fun rememberNiaAppState(
 @Stable
 class NiaAppState(
     val navController: NavHostController,
+    val nav3Navigator: Nav3NavigatorSimple,
     coroutineScope: CoroutineScope,
     networkMonitor: NetworkMonitor,
     userNewsResourceRepository: UserNewsResourceRepository,
@@ -169,9 +185,11 @@ class NiaAppState(
             }
 
             when (topLevelDestination) {
-                FOR_YOU -> navController.navigateToForYou(topLevelNavOptions)
-                BOOKMARKS -> navController.navigateToBookmarks(topLevelNavOptions)
-                INTERESTS -> navController.navigateToInterests(null, topLevelNavOptions)
+                FOR_YOU -> nav3Navigator.goTo(route = ForYouRoute, topLevelNavOptions)
+                BOOKMARKS -> nav3Navigator.goTo(route = BookmarksRoute, topLevelNavOptions)
+                INTERESTS -> {
+                    nav3Navigator.goTo(route = InterestsRoute(null), topLevelNavOptions)
+                }
             }
         }
     }
@@ -196,3 +214,107 @@ private fun NavigationTrackingSideEffect(navController: NavHostController) {
         }
     }
 }
+
+class Nav3NavigatorSimple(val navController: NavHostController){
+
+    val coroutineScope = CoroutineScope(Job() + Dispatchers.Main)
+
+    // We need a single element to avoid "backStack cannot be empty" error b/430023647
+    val backStack = mutableStateListOf<Any>(Unit)
+
+    // Expose the current top level route for consumers
+    lateinit var topLevelKey : String
+
+    // key = top level route string, value = route instance
+    private var topLevelStacks : LinkedHashMap<String, MutableList<Any>> = linkedMapOf()
+
+    init {
+        coroutineScope.launch {
+            navController.currentBackStack.collect { nav2BackStack ->
+
+                topLevelStacks.clear()
+
+                val rootNode : NavGraph = navController.graph
+                println("Root node start destination: ${rootNode.startDestinationRoute}")
+
+                nav2BackStack.forEach { entry ->
+
+                    println("\n==ENTRY==")
+                    println("Entry: $entry")
+                    println("Destination: ${entry.destination}")
+                    println("Destination navigatorName: ${entry.destination.navigatorName}")
+                    println("Route: ${entry.destination.route}")
+                    println("Parent destination: ${entry.destination.parent}")
+
+                    val destination = entry.destination
+
+                    // We only care about navigable destinations
+                    if (destination.navigatorName == "composable"){
+
+                        val parentDestination = destination.parent
+                        var stackName = destination.route!!
+
+                        // Convert the entry into a route instance
+                        val routeInstance =
+                            if (destination.hasRoute<BookmarksRoute>()) {
+                                entry.toRoute<BookmarksRoute>()
+                            } else if (destination.hasRoute<TopicRoute>()) {
+                                entry.toRoute<TopicRoute>()
+                            } else if (destination.hasRoute<SearchRoute>()) {
+                                entry.toRoute<SearchRoute>()
+                            } else if (destination.hasRoute<InterestsRoute>()) {
+                                entry.toRoute<InterestsRoute>()
+                            } else if (destination.hasRoute<ForYouRoute>()) {
+                                entry.toRoute<ForYouRoute>()
+                            } else {
+                                // Non migrated top level route
+                                println("Non migrated destination: $destination")
+                                entry
+                            }
+
+                        // For nested stacks, use the parent destination's start destination route
+                        // as the stack name.
+                        if (parentDestination != rootNode){
+                            stackName = parentDestination?.startDestinationRoute!!
+                        }
+                        add(stackName, routeInstance)
+                    }
+                }
+                updateBackStack()
+            }
+        }
+    }
+
+    private fun add(stackName: String, route: Any){
+        if (topLevelStacks[stackName] == null){
+            topLevelStacks.put(stackName, mutableListOf(route))
+        } else {
+            topLevelStacks[stackName]?.add(route)
+        }
+        topLevelKey = stackName
+        updateBackStack()
+    }
+
+    private fun updateBackStack() {
+        backStack.apply {
+            clear()
+            addAll(topLevelStacks.flatMap { it.value })
+        }
+        println("Back stack: $backStack")
+    }
+
+    fun goBack(){
+        val removedKey = topLevelStacks[topLevelKey]?.removeLastOrNull()
+        // If the removed key was a top level key, remove the associated top level stack
+        topLevelStacks.remove(removedKey)
+        topLevelKey = topLevelStacks.keys.last()
+        updateBackStack()
+        navController.popBackStack()
+    }
+
+    fun goTo(route: Any, navOptions: NavOptions? = null){
+        add(topLevelKey, route)
+        navController.navigate(route = route, navOptions = navOptions)
+    }
+}
+