Make ExtensionsViewModel collect extensions only while subscribed (#3729)

Assisted-by: Claude:claude-opus-5

app/src/main/java/eu/kanade/tachiyomi/ui/browse/BrowseTab.kt

@@ -6,9 +6,9 @@ import androidx.compose.animation.graphics.vector.AnimatedImageVector
 import androidx.compose.foundation.pager.rememberPagerState
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
-import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
 import androidx.compose.ui.platform.LocalContext
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.viewmodel.compose.viewModel
 import cafe.adriel.voyager.navigator.Navigator
 import cafe.adriel.voyager.navigator.tab.LocalTabNavigator
@@ -59,7 +59,7 @@ data object BrowseTab : Tab {
 
         // Hoisted for extensions tab's search bar
         val extensionsViewModel = viewModel<ExtensionsViewModel>()
-        val extensionsState by extensionsViewModel.state.collectAsState()
+        val extensionsSearchQuery by extensionsViewModel.searchQuery.collectAsStateWithLifecycle()
 
         val tabs = listOf(
             sourcesTab(),
@@ -73,7 +73,7 @@ data object BrowseTab : Tab {
             titleRes = MR.strings.browse,
             tabs = tabs,
             state = state,
-            searchQuery = extensionsState.searchQuery,
+            searchQuery = extensionsSearchQuery,
             onChangeSearchQuery = extensionsViewModel::search,
         )
         LaunchedEffect(Unit) {

app/src/main/java/eu/kanade/tachiyomi/ui/browse/extension/ExtensionsTab.kt

@@ -5,12 +5,12 @@ import androidx.compose.material3.AlertDialog
 import androidx.compose.material3.Text
 import androidx.compose.material3.TextButton
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.platform.LocalContext
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import cafe.adriel.voyager.navigator.LocalNavigator
 import cafe.adriel.voyager.navigator.currentOrThrow
 import eu.kanade.presentation.browse.ExtensionScreen
@@ -31,12 +31,12 @@ fun extensionsTab(
     val navigator = LocalNavigator.currentOrThrow
     val context = LocalContext.current
 
-    val state by extensionsViewModel.state.collectAsState()
+    val updatesCount by extensionsViewModel.updatesCount.collectAsStateWithLifecycle()
     var privateExtensionToUninstall by remember { mutableStateOf<Extension?>(null) }
 
     return TabContent(
         titleRes = MR.strings.label_extensions,
-        badgeNumber = state.updates.takeIf { it > 0 },
+        badgeNumber = updatesCount.takeIf { it > 0 },
         searchEnabled = true,
         actions = listOf(
             AppBar.OverflowAction(
@@ -49,6 +49,8 @@ fun extensionsTab(
             ),
         ),
         content = { contentPadding, _ ->
+            val state by extensionsViewModel.state.collectAsStateWithLifecycle()
+
             BackHandler(enabled = state.searchQuery != null) {
                 extensionsViewModel.search(null)
             }

app/src/main/java/eu/kanade/tachiyomi/ui/browse/extension/ExtensionsViewModel.kt

@@ -2,6 +2,7 @@ package eu.kanade.tachiyomi.ui.browse.extension
 
 import android.app.Application
 import androidx.compose.runtime.Immutable
+import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import dev.icerock.moko.resources.StringResource
 import eu.kanade.domain.base.BasePreferences
@@ -12,22 +13,24 @@ import eu.kanade.tachiyomi.extension.model.Extension
 import eu.kanade.tachiyomi.extension.model.InstallStep
 import eu.kanade.tachiyomi.source.online.HttpSource
 import eu.kanade.tachiyomi.util.system.LocaleHelper
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.delay
 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.collect
-import kotlinx.coroutines.flow.collectLatest
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.debounce
-import kotlinx.coroutines.flow.distinctUntilChanged
-import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.flowOn
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.onCompletion
 import kotlinx.coroutines.flow.onEach
+import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.flow.takeWhile
 import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
-import mihon.core.viewmodel.StateViewModel
 import tachiyomi.core.common.util.lang.launchIO
 import tachiyomi.i18n.MR
 import uy.kohesive.injekt.Injekt
@@ -35,26 +38,33 @@ import uy.kohesive.injekt.api.get
 import kotlin.time.Duration.Companion.seconds
 
 class ExtensionsViewModel(
-    preferences: SourcePreferences = Injekt.get(),
+    private val preferences: SourcePreferences = Injekt.get(),
     basePreferences: BasePreferences = Injekt.get(),
     private val extensionManager: ExtensionManager = Injekt.get(),
     private val getExtensions: GetExtensionsByType = Injekt.get(),
-) : StateViewModel<ExtensionsViewModel.State>(State()) {
+) : ViewModel() {
 
     private val currentDownloads = MutableStateFlow<Map<String, InstallStep>>(hashMapOf())
 
-    init {
-        val context = Injekt.get<Application>()
-        val extensionMapper: (Map<String, InstallStep>) -> ((Extension) -> ExtensionUiModel.Item) = { map ->
-            {
+    private val context = Injekt.get<Application>()
+
+    // Public so BrowseTab's search bar can observe it without subscribing to the whole state.
+    val searchQuery: StateFlow<String?>
+        field = MutableStateFlow(null)
+
+    // Public so the tab badge can observe it without subscribing to the whole state.
+    val updatesCount = preferences.extensionUpdatesCount.changes()
+        .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5.seconds), 0)
+
+    private val isRefreshing = MutableStateFlow(false)
+
+    private fun extensionMapper(map: Map<String, InstallStep>): (Extension) -> ExtensionUiModel.Item = {
         ExtensionUiModel.Item(it, map[it.pkgName] ?: InstallStep.Idle)
     }
-        }
 
-        viewModelScope.launchIO {
-            combine(
-                state.map { it.searchQuery }
-                    .distinctUntilChanged()
+    @Suppress("LocalVariableName")
+    private val items = combine(
+        searchQuery
             .debounce(0.25.seconds)
             .map { searchQueryPredicate(it ?: "") },
         currentDownloads,
@@ -85,25 +95,29 @@ class ExtensionsViewModel(
             }
         }
     }
-                .collectLatest { items ->
-                    mutableState.update { state ->
-                        state.copy(
-                            isLoading = false,
-                            items = items,
+        .flowOn(Dispatchers.IO)
+        .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5.seconds), null)
+
+    val state: StateFlow<State> = combine(
+        items,
+        searchQuery,
+        isRefreshing,
+        preferences.extensionUpdatesCount.changes(),
+        basePreferences.extensionInstaller.changes(),
+    ) { items, searchQuery, isRefreshing, updates, installer ->
+        State(
+            isLoading = items == null,
+            isRefreshing = isRefreshing,
+            items = items.orEmpty(),
+            updates = updates,
+            installer = installer,
+            searchQuery = searchQuery,
         )
     }
-                }
-        }
+        .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5.seconds), State())
 
+    init {
         viewModelScope.launchIO { findAvailableExtensions() }
-
-        preferences.extensionUpdatesCount.changes()
-            .onEach { mutableState.update { state -> state.copy(updates = it) } }
-            .launchIn(viewModelScope)
-
-        basePreferences.extensionInstaller.changes()
-            .onEach { mutableState.update { state -> state.copy(installer = it) } }
-            .launchIn(viewModelScope)
     }
 
     fun searchQueryPredicate(query: String): (Extension) -> Boolean {
@@ -137,9 +151,7 @@ class ExtensionsViewModel(
     }
 
     fun search(query: String?) {
-        mutableState.update {
-            it.copy(searchQuery = query)
-        }
+        searchQuery.update { query }
     }
 
     fun updateAllExtensions() {
@@ -190,14 +202,14 @@ class ExtensionsViewModel(
 
     fun findAvailableExtensions() {
         viewModelScope.launchIO {
-            mutableState.update { it.copy(isRefreshing = true) }
+            isRefreshing.update { true }
 
             extensionManager.findAvailableExtensions()
 
             // Fake slower refresh so it doesn't seem like it's not doing anything
             delay(1.seconds)
 
-            mutableState.update { it.copy(isRefreshing = false) }
+            isRefreshing.update { false }
         }
     }