Clean up deep link handling

Change-Id: I9d589cfe5c20a6b55708b99f5d79b10271af8ab4

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

@@ -44,7 +44,7 @@ fun NiaNavHost(
     val navController = appState.navController
     NavHost(
         navController = navController,
-        startDestination = ForYouRoute(),
+        startDestination = ForYouRoute,
         modifier = modifier,
     ) {
         forYouScreen(onTopicClick = navController::navigateToInterests)

core/notifications/src/main/kotlin/com/google/samples/apps/nowinandroid/core/notifications/SystemTrayNotifier.kt

@@ -43,8 +43,11 @@ private const val NEWS_NOTIFICATION_REQUEST_CODE = 0
 private const val NEWS_NOTIFICATION_SUMMARY_ID = 1
 private const val NEWS_NOTIFICATION_CHANNEL_ID = ""
 private const val NEWS_NOTIFICATION_GROUP = "NEWS_NOTIFICATIONS"
-const val DEEP_LINK_SCHEME_AND_HOST = "https://www.nowinandroid.apps.samples.google.com"
-const val FOR_YOU_PATH = "foryou"
+private const val DEEP_LINK_SCHEME_AND_HOST = "https://www.nowinandroid.apps.samples.google.com"
+private const val DEEP_LINK_FOR_YOU_PATH = "foryou"
+private const val DEEP_LINK_BASE_PATH = "$DEEP_LINK_SCHEME_AND_HOST/$DEEP_LINK_FOR_YOU_PATH"
+const val DEEP_LINK_NEWS_RESOURCE_ID_KEY = "linkedNewsResourceId"
+const val DEEP_LINK_URI_PATTERN = "$DEEP_LINK_BASE_PATH/{$DEEP_LINK_NEWS_RESOURCE_ID_KEY}"
 
 /**
  * Implementation of [Notifier] that displays notifications in the system tray.
@@ -161,4 +164,4 @@ private fun Context.newsPendingIntent(
     PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE,
 )
 
-private fun NewsResource.newsDeepLinkUri() = "$DEEP_LINK_SCHEME_AND_HOST/$FOR_YOU_PATH/$id".toUri()
+private fun NewsResource.newsDeepLinkUri() = "$DEEP_LINK_BASE_PATH/$id".toUri()

feature/foryou/src/main/kotlin/com/google/samples/apps/nowinandroid/feature/foryou/ForYouViewModel.kt

@@ -27,8 +27,8 @@ import com.google.samples.apps.nowinandroid.core.data.repository.UserDataReposit
 import com.google.samples.apps.nowinandroid.core.data.repository.UserNewsResourceRepository
 import com.google.samples.apps.nowinandroid.core.data.util.SyncManager
 import com.google.samples.apps.nowinandroid.core.domain.GetFollowableTopicsUseCase
+import com.google.samples.apps.nowinandroid.core.notifications.DEEP_LINK_NEWS_RESOURCE_ID_KEY
 import com.google.samples.apps.nowinandroid.core.ui.NewsFeedUiState
-import com.google.samples.apps.nowinandroid.feature.foryou.navigation.LINKED_NEWS_RESOURCE_ID
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.SharingStarted
@@ -55,7 +55,7 @@ class ForYouViewModel @Inject constructor(
         userDataRepository.userData.map { !it.shouldHideOnboarding }
 
     val deepLinkedNewsResource = savedStateHandle.getStateFlow<String?>(
-        key = LINKED_NEWS_RESOURCE_ID,
+        key = DEEP_LINK_NEWS_RESOURCE_ID_KEY,
         null,
     )
         .flatMapLatest { newsResourceId ->
@@ -129,7 +129,7 @@ class ForYouViewModel @Inject constructor(
 
     fun onDeepLinkOpened(newsResourceId: String) {
         if (newsResourceId == deepLinkedNewsResource.value?.id) {
-            savedStateHandle[LINKED_NEWS_RESOURCE_ID] = null
+            savedStateHandle[DEEP_LINK_NEWS_RESOURCE_ID_KEY] = null
         }
         analyticsHelper.logNewsDeepLinkOpen(newsResourceId = newsResourceId)
         viewModelScope.launch {
@@ -153,7 +153,7 @@ private fun AnalyticsHelper.logNewsDeepLinkOpen(newsResourceId: String) =
             type = "news_deep_link_opened",
             extras = listOf(
                 Param(
-                    key = LINKED_NEWS_RESOURCE_ID,
+                    key = DEEP_LINK_NEWS_RESOURCE_ID_KEY,
                     value = newsResourceId,
                 ),
             ),

feature/foryou/src/main/kotlin/com/google/samples/apps/nowinandroid/feature/foryou/navigation/ForYouNavigation.kt

@@ -21,23 +21,27 @@ import androidx.navigation.NavGraphBuilder
 import androidx.navigation.NavOptions
 import androidx.navigation.compose.composable
 import androidx.navigation.navDeepLink
-import com.google.samples.apps.nowinandroid.core.notifications.DEEP_LINK_SCHEME_AND_HOST
-import com.google.samples.apps.nowinandroid.core.notifications.FOR_YOU_PATH
+import com.google.samples.apps.nowinandroid.core.notifications.DEEP_LINK_URI_PATTERN
 import com.google.samples.apps.nowinandroid.feature.foryou.ForYouScreen
 import kotlinx.serialization.Serializable
 
-const val LINKED_NEWS_RESOURCE_ID = "linkedNewsResourceId"
+@Serializable data object ForYouRoute
 
-private const val DEEP_LINK_BASE_PATH = "$DEEP_LINK_SCHEME_AND_HOST/$FOR_YOU_PATH"
-
-@Serializable data class ForYouRoute(val linkedNewsResourceId: String? = null)
-
-fun NavController.navigateToForYou(navOptions: NavOptions) = navigate(route = ForYouRoute(), navOptions)
+fun NavController.navigateToForYou(navOptions: NavOptions) = navigate(route = ForYouRoute, navOptions)
 
 fun NavGraphBuilder.forYouScreen(onTopicClick: (String) -> Unit) {
     composable<ForYouRoute>(
         deepLinks = listOf(
-            navDeepLink<ForYouRoute>(basePath = DEEP_LINK_BASE_PATH),
+            navDeepLink {
+                /**
+                 * This destination has a deep link that enables a specific news resource to be
+                 * opened from a notification (@see SystemTrayNotifier for more). The news resource
+                 * ID is sent in the URI rather than being modelled in the route type because it's
+                 * transient data (stored in SavedStateHandle) that is cleared after the user has
+                 * opened the news resource.
+                 */
+                uriPattern = DEEP_LINK_URI_PATTERN
+            }
         ),
     ) {
         ForYouScreen(onTopicClick)