toast a friendly message for playback connection errors

Map the Media3 network/HTTP error codes to readable text and show it as a toast, instead of leaving an opaque ERR_ code on the now playing screen.

app/src/main/kotlin/com/subtracks/di/AppModule.kt

@@ -45,7 +45,7 @@ fun appModule(
     single { SyncManager(get(), get(), get()) }
     single { QueueRepository(get()) }
     single<PlayerConnection> { MediaSessionConnection(context.applicationContext, get()) }
-    single { PlaybackController(get(), get(), get()) }
+    single { PlaybackController(get(), get(), get(), showMessage = toast) }
     viewModel { RootViewModel(get()) }
     viewModel { LibraryViewModel(get(), get(), get(), get(), get()) }
     viewModel { SettingsViewModel(get(), get()) }

app/src/main/kotlin/com/subtracks/playback/Media3PlayerHandle.kt

@@ -111,7 +111,7 @@ class Media3PlayerHandle(
                         "Playback error ${error.errorCodeName} at ${controller.currentPosition}/${controller.duration}",
                         error,
                     )
-                    listener.onError(error.errorCodeName)
+                    listener.onError(playbackErrorMessage(error))
                 }
 
                 override fun onPlaybackStateChanged(playbackState: Int) {
@@ -171,3 +171,14 @@ class Media3PlayerHandle(
         const val EXTRA_DURATION_MS = "durationMs"
     }
 }
+
+internal fun playbackErrorMessage(error: PlaybackException): String =
+    when (error.errorCode) {
+        PlaybackException.ERROR_CODE_IO_NETWORK_CONNECTION_FAILED,
+        PlaybackException.ERROR_CODE_IO_NETWORK_CONNECTION_TIMEOUT,
+        -> "Can't reach the server. Check your connection."
+
+        PlaybackException.ERROR_CODE_IO_BAD_HTTP_STATUS -> "The server refused to stream this track."
+
+        else -> error.errorCodeName
+    }

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

@@ -98,6 +98,7 @@ class PlaybackController(
     private val sourceRepository: SourceRepository,
     private val queueRepository: QueueRepository,
     private val connection: PlayerConnection,
+    private val showMessage: (String) -> Unit = {},
     dispatcher: CoroutineDispatcher = Dispatchers.Main.immediate,
 ) {
     private val scope = CoroutineScope(SupervisorJob() + dispatcher)
@@ -870,6 +871,7 @@ class PlaybackController(
 
             override fun onError(message: String) {
                 lastError = message
+                showMessage(message)
                 refresh()
             }
         }

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

@@ -1,6 +1,7 @@
 package com.subtracks.playback
 
 import android.content.Context
+import androidx.media3.common.PlaybackException
 import androidx.room3.Room
 import androidx.sqlite.driver.bundled.BundledSQLiteDriver
 import androidx.test.core.app.ApplicationProvider
@@ -45,6 +46,7 @@ class PlaybackControllerTest {
     private lateinit var queues: QueueRepository
     private lateinit var handle: FakePlayerHandle
     private lateinit var controller: PlaybackController
+    private val messages = CopyOnWriteArrayList<String>()
 
     @Before
     fun setUp() {
@@ -59,7 +61,8 @@ class PlaybackControllerTest {
         sources = SourceRepository(db, OkHttpClient(), prefs, networkMode = networkMode)
         queues = QueueRepository(db)
         handle = FakePlayerHandle()
-        controller = PlaybackController(sources, queues, FakePlayerConnection(handle), dispatcher = dispatcher)
+        controller =
+            PlaybackController(sources, queues, FakePlayerConnection(handle), showMessage = { messages += it }, dispatcher = dispatcher)
     }
 
     @After
@@ -299,6 +302,29 @@ class PlaybackControllerTest {
         assertEquals(null, controller.state.value.error)
     }
 
+    @Test
+    fun playbackErrorsAreShownAsAToast() {
+        seedAlbum(3, sourceId = 1)
+        controller.playAlbum(1, "al1", 0)
+        await { handle.operations.contains("play") }
+
+        handle.fail("Can't reach the server. Check your connection.")
+        await { messages.isNotEmpty() }
+
+        assertEquals(listOf("Can't reach the server. Check your connection."), messages.toList())
+    }
+
+    @Test
+    fun networkErrorsAreReportedWithAFriendlyMessage() {
+        val failed = PlaybackException("net", null, PlaybackException.ERROR_CODE_IO_NETWORK_CONNECTION_FAILED)
+        val timeout = PlaybackException("net", null, PlaybackException.ERROR_CODE_IO_NETWORK_CONNECTION_TIMEOUT)
+        val refused = PlaybackException("http", null, PlaybackException.ERROR_CODE_IO_BAD_HTTP_STATUS)
+
+        assertEquals("Can't reach the server. Check your connection.", playbackErrorMessage(failed))
+        assertEquals("Can't reach the server. Check your connection.", playbackErrorMessage(timeout))
+        assertEquals("The server refused to stream this track.", playbackErrorMessage(refused))
+    }
+
     @Test
     fun startingAnEmptyQueueStopsThePlayer() {
         seedAlbum(3, sourceId = 1)

app/src/test/kotlin/com/subtracks/ui/playback/QueueViewModelTest.kt

@@ -51,7 +51,7 @@ class QueueViewModelTest {
                 .build()
         val sources = SourceRepository(db, OkHttpClient(), fakeUserPreferences())
         queues = QueueRepository(db)
-        controller = PlaybackController(sources, queues, FakePlayerConnection(FakePlayerHandle()), dispatcher)
+        controller = PlaybackController(sources, queues, FakePlayerConnection(FakePlayerHandle()), dispatcher = dispatcher)
         viewModel = QueueViewModel(queues, controller)
     }