Refactor - using `StateInViewModelScope()` extension function inside ViewModels

This commit also includes refactoring for functions, making functions more clear by extracting them inside ViewModels.

app/src/main/java/com/google/samples/apps/nowinandroid/MainActivityViewModel.kt

@@ -22,12 +22,11 @@ import com.google.samples.apps.nowinandroid.MainActivityUiState.Loading
 import com.google.samples.apps.nowinandroid.MainActivityUiState.Success
 import com.google.samples.apps.nowinandroid.core.data.repository.UserDataRepository
 import com.google.samples.apps.nowinandroid.core.model.data.UserData
+import com.google.samples.apps.nowinandroid.core.ui.stateInViewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
 import javax.inject.Inject
-import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.map
-import kotlinx.coroutines.flow.stateIn
 
 @HiltViewModel
 class MainActivityViewModel @Inject constructor(
@@ -35,11 +34,7 @@ class MainActivityViewModel @Inject constructor(
 ) : ViewModel() {
     val uiState: StateFlow<MainActivityUiState> = userDataRepository.userDataStream.map {
         Success(it)
-    }.stateIn(
-        scope = viewModelScope,
-        initialValue = Loading,
-        started = SharingStarted.WhileSubscribed(5_000)
-    )
+    }.stateInViewModelScope(viewModelScope, initialValue = Loading)
 }
 
 sealed interface MainActivityUiState {

feature/author/src/main/java/com/google/samples/apps/nowinandroid/feature/author/AuthorViewModel.kt

@@ -27,17 +27,19 @@ import com.google.samples.apps.nowinandroid.core.domain.model.FollowableAuthor
 import com.google.samples.apps.nowinandroid.core.domain.model.SaveableNewsResource
 import com.google.samples.apps.nowinandroid.core.model.data.Author
 import com.google.samples.apps.nowinandroid.core.result.Result
+import com.google.samples.apps.nowinandroid.core.result.Result.Error
+import com.google.samples.apps.nowinandroid.core.result.Result.Loading
+import com.google.samples.apps.nowinandroid.core.result.Result.Success
 import com.google.samples.apps.nowinandroid.core.result.asResult
+import com.google.samples.apps.nowinandroid.core.ui.stateInViewModelScope
 import com.google.samples.apps.nowinandroid.feature.author.navigation.AuthorArgs
 import dagger.hilt.android.lifecycle.HiltViewModel
-import javax.inject.Inject
 import kotlinx.coroutines.flow.Flow
-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 javax.inject.Inject
 
 @HiltViewModel
 class AuthorViewModel @Inject constructor(
@@ -54,75 +56,67 @@ class AuthorViewModel @Inject constructor(
         authorId = authorArgs.authorId,
         userDataRepository = userDataRepository,
         authorsRepository = authorsRepository
-    )
-        .stateIn(
-            scope = viewModelScope,
-            started = SharingStarted.WhileSubscribed(5_000),
-            initialValue = AuthorUiState.Loading
-        )
+    ).stateInViewModelScope(viewModelScope, initialValue = AuthorUiState.Loading)
 
-    val newsUiState: StateFlow<NewsUiState> =
-        getSaveableNewsResourcesStream.newsUiStateStream(authorId = authorArgs.authorId)
-            .stateIn(
-                scope = viewModelScope,
-                started = SharingStarted.WhileSubscribed(5_000),
-                initialValue = NewsUiState.Loading
-            )
+    val newsUiState: StateFlow<NewsUiState> = getSaveableNewsResourcesStream
+        .newsUiStateStream(authorId = authorArgs.authorId)
+        .stateInViewModelScope(viewModelScope, initialValue = NewsUiState.Loading)
 
-    fun followAuthorToggle(followed: Boolean) {
-        viewModelScope.launch {
-            userDataRepository.toggleFollowedAuthorId(authorArgs.authorId, followed)
-        }
+    fun followAuthorToggle(followed: Boolean) = viewModelScope.launch {
+        userDataRepository.toggleFollowedAuthorId(authorArgs.authorId, followed)
     }
 
-    fun bookmarkNews(newsResourceId: String, bookmarked: Boolean) {
-        viewModelScope.launch {
-            userDataRepository.updateNewsResourceBookmark(newsResourceId, bookmarked)
-        }
+    fun bookmarkNews(newsResourceId: String, bookmarked: Boolean) = viewModelScope.launch {
+        userDataRepository.updateNewsResourceBookmark(newsResourceId, bookmarked)
     }
-}
 
-private fun authorUiStateStream(
-    authorId: String,
-    userDataRepository: UserDataRepository,
-    authorsRepository: AuthorsRepository,
-): Flow<AuthorUiState> {
-    // Observe the followed authors, as they could change over time.
-    val followedAuthorIdsStream: Flow<Set<String>> =
-        userDataRepository.userDataStream
-            .map { it.followedAuthors }
-
-    // Observe author information
-    val authorStream: Flow<Author> = authorsRepository.getAuthorStream(
-        id = authorId
-    )
-
-    return combine(
-        followedAuthorIdsStream,
-        authorStream,
-        ::Pair
-    )
-        .asResult()
-        .map { followedAuthorToAuthorResult ->
-            when (followedAuthorToAuthorResult) {
-                is Result.Success -> {
-                    val (followedAuthors, author) = followedAuthorToAuthorResult.data
-                    val followed = followedAuthors.contains(authorId)
-                    AuthorUiState.Success(
-                        followableAuthor = FollowableAuthor(
-                            author = author,
-                            isFollowed = followed
-                        )
-                    )
-                }
-                is Result.Loading -> {
-                    AuthorUiState.Loading
-                }
-                is Result.Error -> {
-                    AuthorUiState.Error
-                }
+    private fun authorUiStateStream(
+        authorId: String,
+        userDataRepository: UserDataRepository,
+        authorsRepository: AuthorsRepository,
+    ): Flow<AuthorUiState> {
+        // Observe the followed authors, as they could change over time.
+        val followedAuthorIdsStream: Flow<Set<String>> =
+            userDataRepository.userDataStream.map { it.followedAuthors }
+
+        // Observe author information
+        val authorStream: Flow<Author> = authorsRepository.getAuthorStream(
+            id = authorId
+        )
+
+        return combine(
+            followedAuthorIdsStream,
+            authorStream,
+            ::Pair
+        )
+            .asResult()
+            .map { followedAuthorToAuthorResult ->
+                handleToAuthorResult(followedAuthorToAuthorResult, authorId)
             }
-        }
+    }
+
+    private fun handleToAuthorResult(
+        followedAuthorToAuthorResult: Result<Pair<Set<String>, Author>>,
+        authorId: String
+    ) = when (followedAuthorToAuthorResult) {
+        is Success -> onSuccessResult(followedAuthorToAuthorResult, authorId)
+        is Loading -> AuthorUiState.Loading
+        is Error -> AuthorUiState.Error
+    }
+
+    private fun onSuccessResult(
+        followedAuthorToAuthorResult: Success<Pair<Set<String>, Author>>,
+        authorId: String
+    ): AuthorUiState.Success {
+        val (followedAuthors, author) = followedAuthorToAuthorResult.data
+        val followed = followedAuthors.contains(authorId)
+        return AuthorUiState.Success(
+            followableAuthor = FollowableAuthor(
+                author = author,
+                isFollowed = followed
+            )
+        )
+    }
 }
 
 private fun GetSaveableNewsResourcesStreamUseCase.newsUiStateStream(
@@ -134,9 +128,9 @@ private fun GetSaveableNewsResourcesStreamUseCase.newsUiStateStream(
     ).asResult()
         .map { newsResult ->
             when (newsResult) {
-                is Result.Success -> NewsUiState.Success(newsResult.data)
-                is Result.Loading -> NewsUiState.Loading
-                is Result.Error -> NewsUiState.Error
+                is Success -> NewsUiState.Success(newsResult.data)
+                is Loading -> NewsUiState.Loading
+                is Error -> NewsUiState.Error
             }
         }
 }

feature/bookmarks/src/main/java/com/google/samples/apps/nowinandroid/feature/bookmarks/BookmarksViewModel.kt

@@ -23,14 +23,13 @@ import com.google.samples.apps.nowinandroid.core.domain.GetSaveableNewsResources
 import com.google.samples.apps.nowinandroid.core.domain.model.SaveableNewsResource
 import com.google.samples.apps.nowinandroid.core.ui.NewsFeedUiState
 import com.google.samples.apps.nowinandroid.core.ui.NewsFeedUiState.Loading
+import com.google.samples.apps.nowinandroid.core.ui.stateInViewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
 import javax.inject.Inject
-import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.filterNot
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.onStart
-import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
 
 @HiltViewModel
@@ -44,15 +43,9 @@ class BookmarksViewModel @Inject constructor(
         .map { newsResources -> newsResources.filter(SaveableNewsResource::isSaved) } // Only show bookmarked news resources.
         .map<List<SaveableNewsResource>, NewsFeedUiState>(NewsFeedUiState::Success)
         .onStart { emit(Loading) }
-        .stateIn(
-            scope = viewModelScope,
-            started = SharingStarted.WhileSubscribed(5_000),
-            initialValue = Loading
-        )
+        .stateInViewModelScope(viewModelScope, initialValue = Loading)
 
-    fun removeFromSavedResources(newsResourceId: String) {
-        viewModelScope.launch {
-            userDataRepository.updateNewsResourceBookmark(newsResourceId, false)
-        }
+    fun removeFromSavedResources(newsResourceId: String) = viewModelScope.launch {
+        userDataRepository.updateNewsResourceBookmark(newsResourceId, false)
     }
 }

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

@@ -25,17 +25,16 @@ import com.google.samples.apps.nowinandroid.core.domain.GetSaveableNewsResources
 import com.google.samples.apps.nowinandroid.core.domain.GetSortedFollowableAuthorsStreamUseCase
 import com.google.samples.apps.nowinandroid.core.domain.model.SaveableNewsResource
 import com.google.samples.apps.nowinandroid.core.ui.NewsFeedUiState
+import com.google.samples.apps.nowinandroid.core.ui.stateInViewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
 import javax.inject.Inject
 import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.flowOf
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.onStart
-import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
 
 @HiltViewModel
@@ -50,12 +49,9 @@ class ForYouViewModel @Inject constructor(
     private val shouldShowOnboarding: Flow<Boolean> =
         userDataRepository.userDataStream.map { !it.shouldHideOnboarding }
 
-    val isSyncing = syncStatusMonitor.isSyncing
-        .stateIn(
-            scope = viewModelScope,
-            started = SharingStarted.WhileSubscribed(5_000),
-            initialValue = false
-        )
+    val isSyncing = syncStatusMonitor
+        .isSyncing
+        .stateInViewModelScope(viewModelScope, initialValue = false)
 
     val feedState: StateFlow<NewsFeedUiState> =
         userDataRepository.userDataStream
@@ -79,11 +75,7 @@ class ForYouViewModel @Inject constructor(
             // As the selected topics and topic state changes, this will cancel the old feed
             // monitoring and start the new one.
             .flatMapLatest { it }
-            .stateIn(
-                scope = viewModelScope,
-                started = SharingStarted.WhileSubscribed(5_000),
-                initialValue = NewsFeedUiState.Loading
-            )
+            .stateInViewModelScope(viewModelScope, initialValue = NewsFeedUiState.Loading)
 
     val onboardingUiState: StateFlow<OnboardingUiState> =
         combine(
@@ -99,23 +91,14 @@ class ForYouViewModel @Inject constructor(
             } else {
                 OnboardingUiState.NotShown
             }
-        }
-            .stateIn(
-                scope = viewModelScope,
-                started = SharingStarted.WhileSubscribed(5_000),
-                initialValue = OnboardingUiState.Loading
-            )
+        }.stateInViewModelScope(viewModelScope, initialValue = OnboardingUiState.Loading)
 
-    fun updateTopicSelection(topicId: String, isChecked: Boolean) {
-        viewModelScope.launch {
-            userDataRepository.toggleFollowedTopicId(topicId, isChecked)
-        }
+    fun updateTopicSelection(topicId: String, isChecked: Boolean) = viewModelScope.launch {
+        userDataRepository.toggleFollowedTopicId(topicId, isChecked)
     }
 
-    fun updateAuthorSelection(authorId: String, isChecked: Boolean) {
-        viewModelScope.launch {
-            userDataRepository.toggleFollowedAuthorId(authorId, isChecked)
-        }
+    fun updateAuthorSelection(authorId: String, isChecked: Boolean) = viewModelScope.launch {
+        userDataRepository.toggleFollowedAuthorId(authorId, isChecked)
     }
 
     fun updateNewsResourceSaved(newsResourceId: String, isChecked: Boolean) {
@@ -124,10 +107,8 @@ class ForYouViewModel @Inject constructor(
         }
     }
 
-    fun dismissOnboarding() {
-        viewModelScope.launch {
-            userDataRepository.setShouldHideOnboarding(true)
-        }
+    fun dismissOnboarding() = viewModelScope.launch {
+        userDataRepository.setShouldHideOnboarding(true)
     }
 }
 

feature/interests/src/main/java/com/google/samples/apps/nowinandroid/feature/interests/InterestsViewModel.kt

@@ -24,14 +24,13 @@ import com.google.samples.apps.nowinandroid.core.domain.GetSortedFollowableAutho
 import com.google.samples.apps.nowinandroid.core.domain.TopicSortField
 import com.google.samples.apps.nowinandroid.core.domain.model.FollowableAuthor
 import com.google.samples.apps.nowinandroid.core.domain.model.FollowableTopic
+import com.google.samples.apps.nowinandroid.core.ui.stateInViewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
 import javax.inject.Inject
 import kotlinx.coroutines.flow.MutableStateFlow
-import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.combine
-import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
 
@@ -54,22 +53,14 @@ class InterestsViewModel @Inject constructor(
         getSortedFollowableAuthorsStream(),
         getFollowableTopicsStream(sortBy = TopicSortField.NAME),
         InterestsUiState::Interests
-    ).stateIn(
-        scope = viewModelScope,
-        started = SharingStarted.WhileSubscribed(5_000),
-        initialValue = InterestsUiState.Loading
-    )
+    ).stateInViewModelScope(viewModelScope, initialValue = InterestsUiState.Loading)
 
-    fun followTopic(followedTopicId: String, followed: Boolean) {
-        viewModelScope.launch {
-            userDataRepository.toggleFollowedTopicId(followedTopicId, followed)
-        }
+    fun followTopic(followedTopicId: String, followed: Boolean) = viewModelScope.launch {
+        userDataRepository.toggleFollowedTopicId(followedTopicId, followed)
     }
 
-    fun followAuthor(followedAuthorId: String, followed: Boolean) {
-        viewModelScope.launch {
-            userDataRepository.toggleFollowedAuthorId(followedAuthorId, followed)
-        }
+    fun followAuthor(followedAuthorId: String, followed: Boolean) = viewModelScope.launch {
+        userDataRepository.toggleFollowedAuthorId(followedAuthorId, followed)
     }
 
     fun switchTab(newIndex: Int) {

feature/settings/src/main/java/com/google/samples/apps/nowinandroid/feature/settings/SettingsViewModel.kt

@@ -21,6 +21,7 @@ import androidx.lifecycle.viewModelScope
 import com.google.samples.apps.nowinandroid.core.data.repository.UserDataRepository
 import com.google.samples.apps.nowinandroid.core.model.data.DarkThemeConfig
 import com.google.samples.apps.nowinandroid.core.model.data.ThemeBrand
+import com.google.samples.apps.nowinandroid.core.ui.stateInViewModelScope
 import com.google.samples.apps.nowinandroid.feature.settings.SettingsUiState.Loading
 import com.google.samples.apps.nowinandroid.feature.settings.SettingsUiState.Success
 import dagger.hilt.android.lifecycle.HiltViewModel
@@ -28,7 +29,6 @@ import javax.inject.Inject
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.map
-import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
 
 @HiltViewModel
@@ -44,29 +44,23 @@ class SettingsViewModel @Inject constructor(
                         darkThemeConfig = userData.darkThemeConfig
                     )
                 )
-            }
-            .stateIn(
-                scope = viewModelScope,
-                // Starting eagerly means the user data is ready when the SettingsDialog is laid out
-                // for the first time. Without this, due to b/221643630 the layout is done using the
-                // "Loading" text, then replaced with the user editable fields once loaded, however,
-                // the layout height doesn't change meaning all the fields are squashed into a small
-                // scrollable column.
-                // TODO: Change to SharingStarted.WhileSubscribed(5_000) when b/221643630 is fixed
-                started = SharingStarted.Eagerly,
-                initialValue = Loading
-            )
+            }.stateInViewModelScope(viewModelScope, SharingStarted.Eagerly, Loading)
 
-    fun updateThemeBrand(themeBrand: ThemeBrand) {
-        viewModelScope.launch {
-            userDataRepository.setThemeBrand(themeBrand)
-        }
+    /**
+     * Starting eagerly means the user data is ready when the SettingsDialog is laid out
+     * for the first time. Without this, due to b/221643630 the layout is done using the
+     * "Loading" text, then replaced with the user editable fields once loaded, however,
+     * the layout height doesn't change meaning all the fields are squashed into a small
+     * scrollable column.
+     * TODO: Change to SharingStarted.WhileSubscribed(5_000) when b/221643630 is fixed
+     */
+
+    fun updateThemeBrand(themeBrand: ThemeBrand) = viewModelScope.launch {
+        userDataRepository.setThemeBrand(themeBrand)
     }
 
-    fun updateDarkThemeConfig(darkThemeConfig: DarkThemeConfig) {
-        viewModelScope.launch {
-            userDataRepository.setDarkThemeConfig(darkThemeConfig)
-        }
+    fun updateDarkThemeConfig(darkThemeConfig: DarkThemeConfig) = viewModelScope.launch {
+        userDataRepository.setDarkThemeConfig(darkThemeConfig)
     }
 }
 

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

@@ -27,16 +27,18 @@ import com.google.samples.apps.nowinandroid.core.domain.model.FollowableTopic
 import com.google.samples.apps.nowinandroid.core.domain.model.SaveableNewsResource
 import com.google.samples.apps.nowinandroid.core.model.data.Topic
 import com.google.samples.apps.nowinandroid.core.result.Result
+import com.google.samples.apps.nowinandroid.core.result.Result.Error
+import com.google.samples.apps.nowinandroid.core.result.Result.Loading
+import com.google.samples.apps.nowinandroid.core.result.Result.Success
 import com.google.samples.apps.nowinandroid.core.result.asResult
+import com.google.samples.apps.nowinandroid.core.ui.stateInViewModelScope
 import com.google.samples.apps.nowinandroid.feature.topic.navigation.TopicArgs
 import dagger.hilt.android.lifecycle.HiltViewModel
 import javax.inject.Inject
 import kotlinx.coroutines.flow.Flow
-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
 
 @HiltViewModel
@@ -45,7 +47,6 @@ class TopicViewModel @Inject constructor(
     stringDecoder: StringDecoder,
     private val userDataRepository: UserDataRepository,
     topicsRepository: TopicsRepository,
-    // newsRepository: NewsRepository,
     getSaveableNewsResourcesStream: GetSaveableNewsResourcesStreamUseCase
 ) : ViewModel() {
 
@@ -55,34 +56,20 @@ class TopicViewModel @Inject constructor(
         topicId = topicArgs.topicId,
         userDataRepository = userDataRepository,
         topicsRepository = topicsRepository
-    )
-        .stateIn(
-            scope = viewModelScope,
-            started = SharingStarted.WhileSubscribed(5_000),
-            initialValue = TopicUiState.Loading
-        )
+    ).stateInViewModelScope(viewModelScope, initialValue = TopicUiState.Loading)
 
     val newUiState: StateFlow<NewsUiState> = newsUiStateStream(
         topicId = topicArgs.topicId,
         userDataRepository = userDataRepository,
         getSaveableNewsResourcesStream = getSaveableNewsResourcesStream
-    )
-        .stateIn(
-            scope = viewModelScope,
-            started = SharingStarted.WhileSubscribed(5_000),
-            initialValue = NewsUiState.Loading
-        )
+    ).stateInViewModelScope(viewModelScope, initialValue = NewsUiState.Loading)
 
-    fun followTopicToggle(followed: Boolean) {
-        viewModelScope.launch {
-            userDataRepository.toggleFollowedTopicId(topicArgs.topicId, followed)
-        }
+    fun followTopicToggle(followed: Boolean) = viewModelScope.launch {
+        userDataRepository.toggleFollowedTopicId(topicArgs.topicId, followed)
     }
 
-    fun bookmarkNews(newsResourceId: String, bookmarked: Boolean) {
-        viewModelScope.launch {
-            userDataRepository.updateNewsResourceBookmark(newsResourceId, bookmarked)
-        }
+    fun bookmarkNews(newsResourceId: String, bookmarked: Boolean) = viewModelScope.launch {
+        userDataRepository.updateNewsResourceBookmark(newsResourceId, bookmarked)
     }
 }
 
@@ -92,9 +79,9 @@ private fun topicUiStateStream(
     topicsRepository: TopicsRepository,
 ): Flow<TopicUiState> {
     // Observe the followed topics, as they could change over time.
-    val followedTopicIdsStream: Flow<Set<String>> =
-        userDataRepository.userDataStream
-            .map { it.followedTopics }
+    val followedTopicIdsStream: Flow<Set<String>> = userDataRepository
+        .userDataStream
+        .map { it.followedTopics }
 
     // Observe topic information
     val topicStream: Flow<Topic> = topicsRepository.getTopic(
@@ -108,27 +95,28 @@ private fun topicUiStateStream(
     )
         .asResult()
         .map { followedTopicToTopicResult ->
-            when (followedTopicToTopicResult) {
-                is Result.Success -> {
-                    val (followedTopics, topic) = followedTopicToTopicResult.data
-                    val followed = followedTopics.contains(topicId)
-                    TopicUiState.Success(
-                        followableTopic = FollowableTopic(
-                            topic = topic,
-                            isFollowed = followed
-                        )
-                    )
-                }
-                is Result.Loading -> {
-                    TopicUiState.Loading
-                }
-                is Result.Error -> {
-                    TopicUiState.Error
-                }
-            }
+            handleTopicResult(followedTopicToTopicResult, topicId)
         }
 }
 
+private fun handleTopicResult(
+    followedTopicToTopicResult: Result<Pair<Set<String>, Topic>>,
+    topicId: String
+) = when (followedTopicToTopicResult) {
+    is Success -> {
+        val (followedTopics, topic) = followedTopicToTopicResult.data
+        val followed = followedTopics.contains(topicId)
+        TopicUiState.Success(
+            followableTopic = FollowableTopic(
+                topic = topic,
+                isFollowed = followed
+            )
+        )
+    }
+    is Loading -> TopicUiState.Loading
+    is Error -> TopicUiState.Error
+}
+
 private fun newsUiStateStream(
     topicId: String,
     getSaveableNewsResourcesStream: GetSaveableNewsResourcesStreamUseCase,
@@ -156,12 +144,8 @@ private fun newsUiStateStream(
                     val (news, bookmarks) = newsToBookmarksResult.data
                     NewsUiState.Success(news)
                 }
-                is Result.Loading -> {
-                    NewsUiState.Loading
-                }
-                is Result.Error -> {
-                    NewsUiState.Error
-                }
+                is Result.Loading -> NewsUiState.Loading
+                is Result.Error -> NewsUiState.Error
             }
         }
 }