new: persist preferences across sessions

data/preferences/build.gradle.kts

@@ -3,7 +3,27 @@ plugins {
 }
 
 kotlin {
+    // Adding custom `dependsOn` edges below disables the automatic default hierarchy, so re-apply it
+    // explicitly to keep the standard commonMain/appleMain/iosMain/webMain wiring.
+    applyDefaultHierarchyTemplate()
+
     androidLibrary {
         namespace = "fr.ajaury.gwenedeg.preferences"
     }
+
+    sourceSets {
+        // Persistence via DataStore for every target that has an artifact for it (Android, iOS,
+        // Desktop). Web (JS/Wasm) has no DataStore artifact, so it keeps commonMain's in-memory
+        // implementation.
+        val dataStoreMain by creating {
+            dependsOn(commonMain.get())
+            dependencies {
+                implementation(libs.androidx.datastore.preferences.core)
+                implementation(libs.okio)
+            }
+        }
+        androidMain.get().dependsOn(dataStoreMain)
+        jvmMain.get().dependsOn(dataStoreMain)
+        iosMain.get().dependsOn(dataStoreMain)
+    }
 }

data/preferences/src/androidMain/kotlin/fr/ajaury/gwenedeg/preferences/di/PreferencesModule.android.kt

@@ -0,0 +1,20 @@
+package fr.ajaury.gwenedeg.preferences.di
+
+import android.content.Context
+import fr.ajaury.gwenedeg.preferences.data.DATA_STORE_FILE_NAME
+import fr.ajaury.gwenedeg.preferences.data.DataStorePreferencesRepository
+import fr.ajaury.gwenedeg.preferences.data.createPreferencesDataStore
+import fr.ajaury.gwenedeg.preferences.domain.PreferencesRepository
+import org.koin.core.module.Module
+import org.koin.dsl.module
+
+actual val preferencesModule: Module = module {
+    single<PreferencesRepository> {
+        val context = get<Context>()
+        DataStorePreferencesRepository(
+            createPreferencesDataStore {
+                context.filesDir.resolve(DATA_STORE_FILE_NAME).absolutePath
+            },
+        )
+    }
+}

data/preferences/src/commonMain/kotlin/fr/ajaury/gwenedeg/preferences/data/InMemoryPreferencesRepository.kt

@@ -8,22 +8,26 @@ import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.update
 
-internal class PreferencesRepositoryImpl : PreferencesRepository {
+/**
+ * In-memory [PreferencesRepository] used on platforms without a DataStore artifact (web). Values do
+ * not survive an app restart / page reload.
+ */
+internal class InMemoryPreferencesRepository : PreferencesRepository {
     private val subtitleState = MutableStateFlow(SubtitlePreferences())
     override val subtitlePreferences: StateFlow<SubtitlePreferences> = subtitleState.asStateFlow()
 
     private val playbackState = MutableStateFlow(PlaybackPreferences())
     override val playbackPreferences: StateFlow<PlaybackPreferences> = playbackState.asStateFlow()
 
-    override fun setShowTranscription(enabled: Boolean) {
+    override suspend fun setShowTranscription(enabled: Boolean) {
         subtitleState.update { it.copy(showTranscription = enabled) }
     }
 
-    override fun setShowTranslation(enabled: Boolean) {
+    override suspend fun setShowTranslation(enabled: Boolean) {
         subtitleState.update { it.copy(showTranslation = enabled) }
     }
 
-    override fun setPlaybackSpeed(speed: Float) {
+    override suspend fun setPlaybackSpeed(speed: Float) {
         playbackState.update { it.copy(speed = speed) }
     }
 }

data/preferences/src/commonMain/kotlin/fr/ajaury/gwenedeg/preferences/di/PreferencesModule.kt

@@ -1,12 +1,9 @@
 package fr.ajaury.gwenedeg.preferences.di
 
-import fr.ajaury.gwenedeg.preferences.data.PreferencesRepositoryImpl
-import fr.ajaury.gwenedeg.preferences.domain.PreferencesRepository
 import org.koin.core.module.Module
-import org.koin.core.module.dsl.bind
-import org.koin.core.module.dsl.singleOf
-import org.koin.dsl.module
 
-val preferencesModule: Module = module {
+/**
-    singleOf(::PreferencesRepositoryImpl) { bind<PreferencesRepository>() }
+ * Binds [fr.ajaury.gwenedeg.preferences.domain.PreferencesRepository]. Persisted with DataStore on
-}
+ * every target that ships it (Android, iOS, Desktop); web falls back to an in-memory implementation.
+ */
+expect val preferencesModule: Module

data/preferences/src/commonMain/kotlin/fr/ajaury/gwenedeg/preferences/domain/PreferencesRepository.kt

@@ -2,16 +2,16 @@ package fr.ajaury.gwenedeg.preferences.domain
 
 import fr.ajaury.gwenedeg.preferences.model.PlaybackPreferences
 import fr.ajaury.gwenedeg.preferences.model.SubtitlePreferences
-import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.Flow
 
 interface PreferencesRepository {
-    val subtitlePreferences: StateFlow<SubtitlePreferences>
+    val subtitlePreferences: Flow<SubtitlePreferences>
 
-    val playbackPreferences: StateFlow<PlaybackPreferences>
+    val playbackPreferences: Flow<PlaybackPreferences>
 
-    fun setShowTranscription(enabled: Boolean)
+    suspend fun setShowTranscription(enabled: Boolean)
 
-    fun setShowTranslation(enabled: Boolean)
+    suspend fun setShowTranslation(enabled: Boolean)
 
-    fun setPlaybackSpeed(speed: Float)
+    suspend fun setPlaybackSpeed(speed: Float)
 }

data/preferences/src/dataStoreMain/kotlin/fr/ajaury/gwenedeg/preferences/data/DataStorePreferencesRepository.kt

@@ -0,0 +1,59 @@
+package fr.ajaury.gwenedeg.preferences.data
+
+import androidx.datastore.core.DataStore
+import androidx.datastore.preferences.core.MutablePreferences
+import androidx.datastore.preferences.core.Preferences
+import androidx.datastore.preferences.core.booleanPreferencesKey
+import androidx.datastore.preferences.core.edit
+import androidx.datastore.preferences.core.floatPreferencesKey
+import fr.ajaury.gwenedeg.preferences.domain.PreferencesRepository
+import fr.ajaury.gwenedeg.preferences.model.PlaybackPreferences
+import fr.ajaury.gwenedeg.preferences.model.SubtitlePreferences
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.map
+
+/**
+ * [PreferencesRepository] persisting to a Preferences [DataStore]. Reads are exposed as hot
+ * [StateFlow]s seeded with the defaults; writes are fire-and-forget on a background scope.
+ */
+internal class DataStorePreferencesRepository(
+    private val dataStore: DataStore<Preferences>,
+) : PreferencesRepository {
+    override val subtitlePreferences: Flow<SubtitlePreferences> =
+        dataStore.data
+            .map { it.toSubtitlePreferences() }
+
+    override val playbackPreferences: Flow<PlaybackPreferences> =
+        dataStore.data
+            .map { it.toPlaybackPreferences() }
+
+    override suspend fun setShowTranscription(enabled: Boolean) = edit { it[ShowTranscriptionKey] = enabled }
+
+    override suspend fun setShowTranslation(enabled: Boolean) = edit { it[ShowTranslationKey] = enabled }
+
+    override suspend fun setPlaybackSpeed(speed: Float) = edit { it[PlaybackSpeedKey] = speed }
+
+    private suspend fun edit(transform: (MutablePreferences) -> Unit) {
+        dataStore.edit(transform)
+    }
+
+    private fun Preferences.toSubtitlePreferences(): SubtitlePreferences {
+        val defaults = SubtitlePreferences()
+        return SubtitlePreferences(
+            showTranscription = this[ShowTranscriptionKey] ?: defaults.showTranscription,
+            showTranslation = this[ShowTranslationKey] ?: defaults.showTranslation,
+        )
+    }
+
+    private fun Preferences.toPlaybackPreferences(): PlaybackPreferences =
+        PlaybackPreferences(
+            speed = this[PlaybackSpeedKey] ?: PlaybackPreferences.DEFAULT_SPEED,
+        )
+
+    private companion object {
+        val ShowTranscriptionKey = booleanPreferencesKey("show_transcription")
+        val ShowTranslationKey = booleanPreferencesKey("show_translation")
+        val PlaybackSpeedKey = floatPreferencesKey("playback_speed")
+    }
+}

data/preferences/src/dataStoreMain/kotlin/fr/ajaury/gwenedeg/preferences/data/PreferencesDataStore.kt

@@ -0,0 +1,12 @@
+package fr.ajaury.gwenedeg.preferences.data
+
+import androidx.datastore.core.DataStore
+import androidx.datastore.preferences.core.PreferenceDataStoreFactory
+import androidx.datastore.preferences.core.Preferences
+import okio.Path.Companion.toPath
+
+internal const val DATA_STORE_FILE_NAME = "gwenedeg.preferences_pb"
+
+/** Builds a Preferences [DataStore] backed by the file at [producePath]. */
+internal fun createPreferencesDataStore(producePath: () -> String): DataStore<Preferences> =
+    PreferenceDataStoreFactory.createWithPath(produceFile = { producePath().toPath() })

data/preferences/src/iosMain/kotlin/fr/ajaury/gwenedeg/preferences/di/PreferencesModule.ios.kt

@@ -0,0 +1,32 @@
+@file:OptIn(ExperimentalForeignApi::class)
+
+package fr.ajaury.gwenedeg.preferences.di
+
+import fr.ajaury.gwenedeg.preferences.data.DATA_STORE_FILE_NAME
+import fr.ajaury.gwenedeg.preferences.data.DataStorePreferencesRepository
+import fr.ajaury.gwenedeg.preferences.data.createPreferencesDataStore
+import fr.ajaury.gwenedeg.preferences.domain.PreferencesRepository
+import kotlinx.cinterop.ExperimentalForeignApi
+import org.koin.core.module.Module
+import org.koin.dsl.module
+import platform.Foundation.NSDocumentDirectory
+import platform.Foundation.NSFileManager
+import platform.Foundation.NSUserDomainMask
+
+actual val preferencesModule: Module = module {
+    single<PreferencesRepository> {
+        DataStorePreferencesRepository(
+            createPreferencesDataStore {
+                val documentDirectory = NSFileManager.defaultManager.URLForDirectory(
+                    directory = NSDocumentDirectory,
+                    inDomain = NSUserDomainMask,
+                    appropriateForURL = null,
+                    create = false,
+                    error = null,
+                )
+                val path = requireNotNull(documentDirectory?.path) { "Missing documents directory" }
+                "$path/$DATA_STORE_FILE_NAME"
+            },
+        )
+    }
+}

data/preferences/src/jvmMain/kotlin/fr/ajaury/gwenedeg/preferences/di/PreferencesModule.jvm.kt

@@ -0,0 +1,20 @@
+package fr.ajaury.gwenedeg.preferences.di
+
+import fr.ajaury.gwenedeg.preferences.data.DATA_STORE_FILE_NAME
+import fr.ajaury.gwenedeg.preferences.data.DataStorePreferencesRepository
+import fr.ajaury.gwenedeg.preferences.data.createPreferencesDataStore
+import fr.ajaury.gwenedeg.preferences.domain.PreferencesRepository
+import org.koin.core.module.Module
+import org.koin.dsl.module
+import java.io.File
+
+actual val preferencesModule: Module = module {
+    single<PreferencesRepository> {
+        DataStorePreferencesRepository(
+            createPreferencesDataStore {
+                val directory = File(System.getProperty("user.home"), ".gwenedeg").apply { mkdirs() }
+                File(directory, DATA_STORE_FILE_NAME).absolutePath
+            },
+        )
+    }
+}

data/preferences/src/webMain/kotlin/fr/ajaury/gwenedeg/preferences/di/PreferencesModule.web.kt

@@ -0,0 +1,12 @@
+package fr.ajaury.gwenedeg.preferences.di
+
+import fr.ajaury.gwenedeg.preferences.data.InMemoryPreferencesRepository
+import fr.ajaury.gwenedeg.preferences.domain.PreferencesRepository
+import org.koin.core.module.Module
+import org.koin.core.module.dsl.bind
+import org.koin.core.module.dsl.singleOf
+import org.koin.dsl.module
+
+actual val preferencesModule: Module = module {
+    singleOf(::InMemoryPreferencesRepository) { bind<PreferencesRepository>() }
+}

gradle/libs.versions.toml

@@ -19,6 +19,8 @@ material3 = "1.11.0-alpha07"
 koin = "4.2.1"
 kermit = "2.1.0"
 vorbisspi = "1.0.3.3"
+datastore = "1.1.1"
+okio = "3.9.1"
 
 [libraries]
 # Gradle plugin artifacts, used by build-logic convention plugins only
@@ -28,6 +30,8 @@ compose-gradlePlugin = { module = "org.jetbrains.compose:compose-gradle-plugin",
 composeCompiler-gradlePlugin = { module = "org.jetbrains.kotlin:compose-compiler-gradle-plugin", version.ref = "kotlin" }
 
 androidx-activity-compose = { module = "androidx.activity:activity-compose", version.ref = "androidxActivity" }
+androidx-datastore-preferences-core = { module = "androidx.datastore:datastore-preferences-core", version.ref = "datastore" }
+okio = { module = "com.squareup.okio:okio", version.ref = "okio" }
 compose-components-resources = { module = "org.jetbrains.compose.components:components-resources", version.ref = "composeMultiplatform" }
 compose-foundation = { module = "org.jetbrains.compose.foundation:foundation", version.ref = "composeMultiplatform" }
 compose-material3 = { module = "org.jetbrains.compose.material3:material3", version.ref = "material3" }

shared/src/commonMain/kotlin/fr/ajaury/gwenedeg/player/ui/viewmodel/PlayerViewModel.kt

@@ -16,6 +16,7 @@ import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.WhileSubscribed
 import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.firstOrNull
 import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
 import kotlin.math.roundToInt
@@ -77,8 +78,9 @@ class PlayerViewModel(
         }
     }
 
-    private fun applyCurrentSpeed() {
+    private suspend fun applyCurrentSpeed() {
-        playbackRepository.setSpeed(preferencesRepository.playbackPreferences.value.speed)
+        val playbackPreferences = preferencesRepository.playbackPreferences.firstOrNull() ?: return
+        playbackRepository.setSpeed(playbackPreferences.speed)
     }
 
     fun performMainPlayAction() {
@@ -111,16 +113,22 @@ class PlayerViewModel(
             PlaybackPreferences.MIN_SPEED,
             PlaybackPreferences.MAX_SPEED,
         )
-        preferencesRepository.setPlaybackSpeed(clampedSpeed)
+        viewModelScope.launch {
-        playbackRepository.setSpeed(clampedSpeed)
+            preferencesRepository.setPlaybackSpeed(clampedSpeed)
+            playbackRepository.setSpeed(clampedSpeed)
+        }
     }
 
     fun setShowTranscription(enabled: Boolean) {
-        preferencesRepository.setShowTranscription(enabled)
+        viewModelScope.launch {
+            preferencesRepository.setShowTranscription(enabled)
+        }
     }
 
     fun setShowTranslation(enabled: Boolean) {
-        preferencesRepository.setShowTranslation(enabled)
+        viewModelScope.launch {
+            preferencesRepository.setShowTranslation(enabled)
+        }
     }
 
     fun stop() {