Make MigrateMangaViewModel collect favorites only while subscribed (#3722)

Assisted-by: Claude:claude-opus-5

app/src/main/java/eu/kanade/tachiyomi/ui/browse/migration/manga/MigrateMangaScreen.kt

@@ -14,11 +14,11 @@ import androidx.compose.material3.Text
 import androidx.compose.material3.animateFloatingActionButton
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
-import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.viewmodel.CreationExtras
 import androidx.lifecycle.viewmodel.compose.viewModel
 import cafe.adriel.voyager.navigator.LocalNavigator
@@ -55,7 +55,7 @@ data class MigrateMangaScreen(
             },
         )
 
-        val state by viewModel.state.collectAsState()
+        val state by viewModel.state.collectAsStateWithLifecycle()
 
         if (state.isLoading) {
             LoadingScreen()

app/src/main/java/eu/kanade/tachiyomi/ui/browse/migration/manga/MigrateMangaViewModel.kt

@@ -1,34 +1,41 @@
 package eu.kanade.tachiyomi.ui.browse.migration.manga
 
 import androidx.compose.runtime.Immutable
+import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import androidx.lifecycle.viewmodel.CreationExtras
 import androidx.lifecycle.viewmodel.initializer
 import androidx.lifecycle.viewmodel.viewModelFactory
 import eu.kanade.tachiyomi.source.Source
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.WhileSubscribed
 import kotlinx.coroutines.flow.catch
-import kotlinx.coroutines.flow.collectLatest
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.flowOn
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.receiveAsFlow
+import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.flow.update
-import kotlinx.coroutines.launch
 import logcat.LogPriority
 import mihon.core.common.utils.mutate
-import mihon.core.viewmodel.StateViewModel
 import tachiyomi.core.common.util.system.logcat
 import tachiyomi.domain.manga.interactor.GetFavorites
 import tachiyomi.domain.manga.model.Manga
 import tachiyomi.domain.source.service.SourceManager
 import uy.kohesive.injekt.Injekt
 import uy.kohesive.injekt.api.get
+import kotlin.time.Duration.Companion.seconds
 
 class MigrateMangaViewModel(
     private val sourceId: Long,
     private val sourceManager: SourceManager = Injekt.get(),
     private val getFavorites: GetFavorites = Injekt.get(),
-) : StateViewModel<MigrateMangaViewModel.State>(State()) {
+) : ViewModel() {
 
     companion object {
         val SOURCE_ID_KEY = CreationExtras.Key<Long>()
@@ -45,41 +52,39 @@ class MigrateMangaViewModel(
     private val _events: Channel<MigrationMangaEvent> = Channel()
     val events: Flow<MigrationMangaEvent> = _events.receiveAsFlow()
 
-    init {
-        viewModelScope.launch {
-            mutableState.update { state ->
-                state.copy(source = sourceManager.getOrStub(sourceId))
-            }
+    private val source by lazy { sourceManager.getOrStub(sourceId) }
 
-            getFavorites.subscribe(sourceId)
-                .catch {
-                    logcat(LogPriority.ERROR, it)
-                    _events.send(MigrationMangaEvent.FailedFetchingFavorites)
-                    mutableState.update { state ->
-                        state.copy(titleList = listOf())
-                    }
-                }
-                .map { manga ->
-                    manga
-                        .sortedWith(compareBy(String.CASE_INSENSITIVE_ORDER) { it.title })
-                }
-                .collectLatest { list ->
-                    mutableState.update { it.copy(titleList = list) }
-                }
+    private val selection = MutableStateFlow(emptySet<Long>())
+
+    private val favorites = getFavorites.subscribe(sourceId)
+        .catch {
+            logcat(LogPriority.ERROR, it)
+            _events.send(MigrationMangaEvent.FailedFetchingFavorites)
+            emit(listOf())
         }
+        .map { manga ->
+            manga.sortedWith(compareBy(String.CASE_INSENSITIVE_ORDER) { it.title })
+        }
+
+    val state: StateFlow<State> = combine(
+        favorites,
+        selection,
+    ) { titleList, selection ->
+        State(source = source, selection = selection, titleList = titleList)
     }
+        .flowOn(Dispatchers.IO)
+        .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5.seconds), State())
 
     fun toggleSelection(item: Manga) {
-        mutableState.update { state ->
-            val selection = state.selection.mutate { list ->
+        selection.update { selection ->
+            selection.mutate { list ->
                 if (!list.remove(item.id)) list.add(item.id)
             }
-            state.copy(selection = selection)
         }
     }
 
     fun clearSelection() {
-        mutableState.update { it.copy(selection = emptySet()) }
+        selection.update { emptySet() }
     }
 
     @Immutable