Assisted inject approach

Change-Id: I5fba15921520bc83b13601fa82ae71457d875805

Author: alexvanyo

app/src/main/kotlin/com/google/samples/apps/nowinandroid/ui/interests2pane/InterestsListDetailScreen.kt

@@ -18,6 +18,7 @@ package com.google.samples.apps.nowinandroid.ui.interests2pane
 
 import androidx.activity.compose.BackHandler
 import androidx.annotation.Keep
+import androidx.compose.animation.AnimatedContent
 import androidx.compose.foundation.interaction.MutableInteractionSource
 import androidx.compose.foundation.layout.Box
 import androidx.compose.material3.LocalMinimumInteractiveComponentSize
@@ -50,13 +51,17 @@ import androidx.compose.ui.layout.layout
 import androidx.compose.ui.unit.dp
 import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import androidx.lifecycle.viewmodel.viewModelFactory
 import androidx.navigation.NavGraphBuilder
 import androidx.navigation.compose.NavHost
 import androidx.navigation.compose.composable
 import androidx.navigation.compose.rememberNavController
 import com.google.samples.apps.nowinandroid.feature.interests.InterestsRoute
 import com.google.samples.apps.nowinandroid.feature.interests.navigation.InterestsRoute
 import com.google.samples.apps.nowinandroid.feature.topic.TopicDetailPlaceholder
+import com.google.samples.apps.nowinandroid.feature.topic.TopicScreen
+import com.google.samples.apps.nowinandroid.feature.topic.TopicViewModel
+import com.google.samples.apps.nowinandroid.feature.topic.TopicViewModel_Factory
 import com.google.samples.apps.nowinandroid.feature.topic.navigation.TopicRoute
 import com.google.samples.apps.nowinandroid.feature.topic.navigation.navigateToTopic
 import com.google.samples.apps.nowinandroid.feature.topic.navigation.topicScreen
@@ -126,28 +131,10 @@ internal fun InterestsListDetailScreen(
         val route = selectedTopicId?.let { TopicRoute(id = it) } ?: TopicPlaceholderRoute
         mutableStateOf(route)
     }
-    var nestedNavKey by rememberSaveable(
-        stateSaver = Saver({ it.toString() }, UUID::fromString),
-    ) {
-        mutableStateOf(UUID.randomUUID())
-    }
-    val nestedNavController = key(nestedNavKey) {
-        rememberNavController()
-    }
 
     fun onTopicClickShowDetailPane(topicId: String) {
         onTopicClick(topicId)
-        if (listDetailNavigator.isDetailPaneVisible()) {
-            // If the detail pane was visible, then use the nestedNavController navigate call
-            // directly
-            nestedNavController.navigateToTopic(topicId) {
-                popUpTo<DetailPaneNavHostRoute>()
-            }
-        } else {
-            // Otherwise, recreate the NavHost entirely, and start at the new destination
-            nestedNavHostStartRoute = TopicRoute(id = topicId)
-            nestedNavKey = UUID.randomUUID()
-        }
+        nestedNavHostStartRoute = TopicRoute(id = topicId)
         coroutineScope.launch {
             listDetailNavigator.navigateTo(ListDetailPaneScaffoldRole.Detail)
         }
@@ -207,22 +194,25 @@ internal fun InterestsListDetailScreen(
                             }
                         },
                 ) {
-                    key(nestedNavKey) {
-                        NavHost(
-                            navController = nestedNavController,
-                            startDestination = nestedNavHostStartRoute,
-                            route = DetailPaneNavHostRoute::class,
-                        ) {
-                            topicScreen(
-                                showBackButton = !listDetailNavigator.isListPaneVisible(),
-                                onBackClick = {
-                                    coroutineScope.launch {
-                                        listDetailNavigator.navigateBack()
+                    AnimatedContent(nestedNavHostStartRoute) { route ->
+                        when (route) {
+                            is TopicRoute -> {
+                                TopicScreen(
+                                    showBackButton = !listDetailNavigator.isListPaneVisible(),
+                                    onBackClick = {
+                                        coroutineScope.launch {
+                                            listDetailNavigator.navigateBack()
+                                        }
+                                    },
+                                    onTopicClick = ::onTopicClickShowDetailPane,
+                                    viewModel = hiltViewModel<TopicViewModel, TopicViewModel.Factory>(
+                                        key = route.id,
+                                    ) { factory ->
+                                        factory.create(route.id)
                                     }
-                                },
-                                onTopicClick = ::onTopicClickShowDetailPane,
-                            )
-                            composable<TopicPlaceholderRoute> {
+                                )
+                            }
+                            is TopicPlaceholderRoute -> {
                                 TopicDetailPlaceholder()
                             }
                         }

feature/topic/src/main/kotlin/com/google/samples/apps/nowinandroid/feature/topic/TopicViewModel.kt

@@ -16,10 +16,8 @@
 
 package com.google.samples.apps.nowinandroid.feature.topic
 
-import androidx.lifecycle.SavedStateHandle
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
-import androidx.navigation.toRoute
 import com.google.samples.apps.nowinandroid.core.data.repository.NewsResourceQuery
 import com.google.samples.apps.nowinandroid.core.data.repository.TopicsRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.UserDataRepository
@@ -29,7 +27,9 @@ import com.google.samples.apps.nowinandroid.core.model.data.Topic
 import com.google.samples.apps.nowinandroid.core.model.data.UserNewsResource
 import com.google.samples.apps.nowinandroid.core.result.Result
 import com.google.samples.apps.nowinandroid.core.result.asResult
-import com.google.samples.apps.nowinandroid.feature.topic.navigation.TopicRoute
+import dagger.assisted.Assisted
+import dagger.assisted.AssistedFactory
+import dagger.assisted.AssistedInject
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.SharingStarted
@@ -38,18 +38,14 @@ import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
-import javax.inject.Inject
 
-@HiltViewModel
-class TopicViewModel @Inject constructor(
-    savedStateHandle: SavedStateHandle,
+@HiltViewModel(assistedFactory = TopicViewModel.Factory::class)
+class TopicViewModel @AssistedInject constructor(
     private val userDataRepository: UserDataRepository,
     topicsRepository: TopicsRepository,
     userNewsResourceRepository: UserNewsResourceRepository,
+    @Assisted val topicId: String,
 ) : ViewModel() {
-
-    val topicId = savedStateHandle.toRoute<TopicRoute>().id
-
     val topicUiState: StateFlow<TopicUiState> = topicUiState(
         topicId = topicId,
         userDataRepository = userDataRepository,
@@ -89,6 +85,13 @@ class TopicViewModel @Inject constructor(
             userDataRepository.setNewsResourceViewed(newsResourceId, viewed)
         }
     }
+
+    @AssistedFactory
+    interface Factory {
+        fun create(
+            topicId: String,
+        ): TopicViewModel
+    }
 }
 
 private fun topicUiState(