persist and restore the playback position within the track

app/src/main/kotlin/com/subtracks/data/db/Migrations.kt

@@ -65,4 +65,11 @@ val MIGRATION_5_6 =
         }
     }
 
-val MIGRATIONS: Array<Migration> = arrayOf(MIGRATION_1_2, MIGRATION_2_3, MIGRATION_3_4, MIGRATION_4_5, MIGRATION_5_6)
+val MIGRATION_6_7 =
+    object : Migration(6, 7) {
+        override suspend fun migrate(connection: SQLiteConnection) {
+            connection.execSQL("ALTER TABLE `playback_cursor` ADD COLUMN `positionMs` INTEGER NOT NULL DEFAULT 0")
+        }
+    }
+
+val MIGRATIONS: Array<Migration> = arrayOf(MIGRATION_1_2, MIGRATION_2_3, MIGRATION_3_4, MIGRATION_4_5, MIGRATION_5_6, MIGRATION_6_7)

app/src/main/kotlin/com/subtracks/data/db/SubtracksDatabase.kt

@@ -32,7 +32,7 @@ import com.subtracks.data.model.SubsonicSource
         ShuffleOrder::class,
         ArtworkSeed::class,
     ],
-    version = 6,
+    version = 7,
     exportSchema = true,
 )
 @ColumnTypeConverters(QueueKindConverter::class)

app/src/main/kotlin/com/subtracks/data/model/Models.kt

@@ -211,6 +211,7 @@ data class PlaybackCursor(
     @ColumnInfo(defaultValue = "0") val shuffleEnabled: Boolean = false,
     @ColumnInfo(defaultValue = "0") val repeatMode: Int = 0,
     @ColumnInfo(defaultValue = "0") val shuffleSeed: Long = 0,
+    @ColumnInfo(defaultValue = "0") val positionMs: Long = 0,
 )
 
 @Entity(tableName = "shuffle_order")

app/src/main/kotlin/com/subtracks/data/repo/QueueRepository.kt

@@ -270,6 +270,10 @@ class QueueRepository(
 
     suspend fun cursor(): Long = dao.cursor()?.queuePosition ?: 0
 
+    suspend fun cursorPositionMs(): Long = dao.cursor()?.positionMs ?: 0
+
+    suspend fun setPosition(positionMs: Long) = dao.setCursor(cursorRow().copy(positionMs = positionMs.coerceAtLeast(0)))
+
     suspend fun setCursor(position: Long) = dao.setCursor(cursorRow().copy(queuePosition = position))
 
     private suspend fun cursorRow(): PlaybackCursor = dao.cursor() ?: PlaybackCursor(queuePosition = 0)

app/src/main/kotlin/com/subtracks/playback/PlaybackController.kt

@@ -123,6 +123,7 @@ class PlaybackController(
     private var shuffleEnabled = false
     private var repeatMode = RepeatMode.Off
     private var endedHandled = false
+    private var lastSavedPositionMs = 0L
 
     init {
         scope.launch {
@@ -463,7 +464,12 @@ class PlaybackController(
             return
         }
         player.ensurePrepared()
-        if (player.playWhenReady) player.pause() else player.play()
+        if (player.playWhenReady) {
+            player.pause()
+            savePosition()
+        } else {
+            player.play()
+        }
     }
 
     fun next() {
@@ -550,6 +556,8 @@ class PlaybackController(
 
     fun seekTo(positionMs: Long) {
         player?.seekTo(positionMs)
+        lastSavedPositionMs = positionMs
+        scope.launch { queueRepository.setPosition(positionMs) }
     }
 
     fun coverArt(
@@ -648,7 +656,8 @@ class PlaybackController(
             }
             this.queueSourceId = queueSourceId
             val position = queueRepository.cursor().coerceIn(0, snapshot.size - 1)
-            loadWindow(position, autoplay = false)
+            lastSavedPositionMs = queueRepository.cursorPositionMs().coerceAtLeast(0)
+            loadWindow(position, autoplay = false, startPositionMs = lastSavedPositionMs)
         }
 
     private suspend fun stop() = startLock.withLock { stopLocked() }
@@ -723,6 +732,7 @@ class PlaybackController(
         val snapshot = snapshot ?: return
         if (snapshot.size == 0L) return
         val position = (windowStart + player.currentIndex).coerceIn(0, snapshot.size - 1)
+        lastSavedPositionMs = 0
         queueRepository.setCursor(position)
         refresh(position)
         scheduleWindowShift(position)
@@ -919,11 +929,23 @@ class PlaybackController(
                 while (true) {
                     delay(POSITION_TICK_MS)
                     val player = player ?: break
-                    _state.value = _state.value.copy(positionMs = player.currentPositionMs)
+                    val positionMs = player.currentPositionMs
+                    _state.value = _state.value.copy(positionMs = positionMs)
+                    if (positionMs - lastSavedPositionMs >= POSITION_SAVE_INTERVAL_MS || positionMs < lastSavedPositionMs) {
+                        lastSavedPositionMs = positionMs
+                        queueRepository.setPosition(positionMs)
+                    }
                 }
             }
     }
 
+    private fun savePosition() {
+        val player = player ?: return
+        val positionMs = player.currentPositionMs
+        lastSavedPositionMs = positionMs
+        scope.launch { queueRepository.setPosition(positionMs) }
+    }
+
     private fun stopPositionTicker() {
         positionJob?.cancel()
         positionJob = null
@@ -935,6 +957,7 @@ class PlaybackController(
 
     private companion object {
         const val POSITION_TICK_MS = 500L
+        const val POSITION_SAVE_INTERVAL_MS = 15_000L
         const val BUFFERING_INDICATOR_DELAY_MS = 1_000L
         const val QUEUE_WINDOW_RADIUS = 25L
         const val WINDOW_SHIFT_DELAY_MS = 400L

app/src/test/kotlin/com/subtracks/playback/FakePlayer.kt

@@ -70,6 +70,7 @@ class FakePlayerHandle : PlayerHandle {
         this.items.clear()
         this.items += items
         index = startIndex
+        positionMs = startPositionMs
         idle = true
         ended = false
         buffering = false

app/src/test/kotlin/com/subtracks/playback/PlaybackControllerTest.kt

@@ -905,6 +905,33 @@ class PlaybackControllerTest {
         assertTrue(controller.state.value.shuffle)
     }
 
+    @Test
+    fun restoringResumesFromTheSavedPosition() {
+        seedAlbum(3, sourceId = 1)
+        controller.playAlbum(1, "al1", 0)
+        await {
+            controller.state.value.item
+                ?.id == "s1"
+        }
+
+        runBlocking { queues.setPosition(12_000L) }
+
+        val restoredHandle = FakePlayerHandle()
+        val restored = PlaybackController(sources, queues, FakePlayerConnection(restoredHandle), dispatcher = dispatcher)
+        restored.connect()
+        await {
+            restored.state.value.item
+                ?.id == "s1"
+        }
+
+        assertEquals(12_000L, restored.state.value.positionMs)
+        assertEquals(
+            "setWindow(size=3, start=0, position=12000)",
+            restoredHandle.operations.first { it.startsWith("setWindow") },
+        )
+        restored.close()
+    }
+
     private fun seedAlbum(
         count: Int,
         sourceId: Long,