functional carplay experience in simulators

ios/Runner/AppDelegate.swift

@@ -2,12 +2,76 @@ import Flutter
 import UIKit
 import AVFoundation
 import AVKit
+import MediaPlayer
+
+private struct CarPlayPlaybackSnapshot {
+  var playbackStatus: String
+  var title: String
+  var subtitle: String
+  var album: String
+  var isLive: Bool
+  var seekable: Bool
+
+  static let `default` = CarPlayPlaybackSnapshot(
+    playbackStatus: "stopped",
+    title: "KRYZ Live Stream",
+    subtitle: "KRYZ Radio",
+    album: "Live",
+    isLive: true,
+    seekable: false
+  )
+
+  init(
+    playbackStatus: String,
+    title: String,
+    subtitle: String,
+    album: String,
+    isLive: Bool,
+    seekable: Bool
+  ) {
+    self.playbackStatus = playbackStatus
+    self.title = title
+    self.subtitle = subtitle
+    self.album = album
+    self.isLive = isLive
+    self.seekable = seekable
+  }
+
+  init(payload: [String: Any], fallback: CarPlayPlaybackSnapshot) {
+    let status = (payload["playbackStatus"] as? String)?.trimmingCharacters(in: .whitespacesAndNewlines)
+    let title = (payload["title"] as? String)?.trimmingCharacters(in: .whitespacesAndNewlines)
+    let subtitle = (payload["subtitle"] as? String)?.trimmingCharacters(in: .whitespacesAndNewlines)
+    let album = (payload["album"] as? String)?.trimmingCharacters(in: .whitespacesAndNewlines)
+
+    playbackStatus = (status?.isEmpty == false) ? status! : fallback.playbackStatus
+    self.title = (title?.isEmpty == false) ? title! : fallback.title
+    self.subtitle = (subtitle?.isEmpty == false) ? subtitle! : fallback.subtitle
+    self.album = (album?.isEmpty == false) ? album! : fallback.album
+    isLive = payload["isLive"] as? Bool ?? fallback.isLive
+    seekable = payload["seekable"] as? Bool ?? fallback.seekable
+  }
+
+  func asDictionary() -> [String: Any] {
+    [
+      "playbackStatus": playbackStatus,
+      "title": title,
+      "subtitle": subtitle,
+      "album": album,
+      "isLive": isLive,
+      "seekable": seekable
+    ]
+  }
+}
 
 @main
 @objc class AppDelegate: FlutterAppDelegate, FlutterImplicitEngineDelegate, FlutterStreamHandler {
   private let castingMethodChannelName = "kryz_go_flutter/casting/methods"
   private let castingEventChannelName = "kryz_go_flutter/casting/events"
   private let playbackMethodChannelName = "kryz_go_flutter/playback/methods"
+  private let carPlayMethodChannelName = "kryz_go_flutter/carplay/methods"
+
+  static let carPlaySnapshotDidChangeNotification = Notification.Name("KRYZCarPlaySnapshotDidChange")
+  static let carPlaySnapshotUserInfoKey = "snapshot"
 
   private var castingEventSink: FlutterEventSink?
   private var castingStatus: [String: Any] = [
@@ -15,6 +79,13 @@ import AVKit
     "platform": "ios"
   ]
   private var playbackMethodChannel: FlutterMethodChannel?
+  private var carPlayMethodChannel: FlutterMethodChannel?
+  private var carPlaySnapshot = CarPlayPlaybackSnapshot.default
+  private var headlessFlutterEngine: FlutterEngine?
+  private var playCommandTarget: Any?
+  private var togglePlayPauseCommandTarget: Any?
+  private var pauseCommandTarget: Any?
+  private var stopCommandTarget: Any?
 
   override func application(
     _ application: UIApplication,
@@ -37,14 +108,67 @@ import AVKit
     )
 
     updateCastingStatusForCurrentRoute()
+    ensureFlutterBridgeReadyForCarPlay()
 
     return super.application(application, didFinishLaunchingWithOptions: launchOptions)
   }
 
   func didInitializeImplicitFlutterEngine(_ engineBridge: FlutterImplicitEngineBridge) {
     GeneratedPluginRegistrant.register(with: engineBridge.pluginRegistry)
+    configureChannels(with: engineBridge.pluginRegistry)
 
-    guard let registrar = engineBridge.pluginRegistry.registrar(forPlugin: "CastingBridge") else {
+    if let engine = headlessFlutterEngine {
+      engine.destroyContext()
+      headlessFlutterEngine = nil
+    }
+  }
+
+  /// Invoke play on the Flutter audio engine. Called by CarPlaySceneDelegate.
+  func invokePlay() {
+    ensureFlutterBridgeReadyForCarPlay()
+    playbackMethodChannel?.invokeMethod("play", arguments: nil)
+  }
+
+  /// Invoke stop on the Flutter audio engine. Called by CarPlaySceneDelegate.
+  func invokeStop() {
+    ensureFlutterBridgeReadyForCarPlay()
+    playbackMethodChannel?.invokeMethod("stop", arguments: nil)
+  }
+
+  func currentCarPlaySnapshot() -> [String: Any] {
+    carPlaySnapshot.asDictionary()
+  }
+
+  func requestCarPlaySnapshot() {
+    ensureFlutterBridgeReadyForCarPlay()
+    carPlayMethodChannel?.invokeMethod("getStateSnapshot", arguments: nil) { [weak self] response in
+      guard let payload = response as? [String: Any] else {
+        return
+      }
+
+      self?.applyCarPlaySnapshot(payload)
+    }
+  }
+
+  func ensureFlutterBridgeReadyForCarPlay() {
+    if playbackMethodChannel != nil, carPlayMethodChannel != nil {
+      return
+    }
+
+    if let engine = headlessFlutterEngine {
+      configureChannels(with: engine)
+      return
+    }
+
+    let engine = FlutterEngine(name: "kryz_carplay_headless_engine", project: nil, allowHeadlessExecution: true)
+    headlessFlutterEngine = engine
+    engine.run()
+    GeneratedPluginRegistrant.register(with: engine)
+    configureChannels(with: engine)
+  }
+
+  private func configureChannels(with registry: FlutterPluginRegistry) {
+    guard let registrar = registry.registrar(forPlugin: "CastingBridge") else {
       return
     }
 
@@ -67,16 +191,17 @@ import AVKit
       name: playbackMethodChannelName,
       binaryMessenger: registrar.messenger()
     )
+
+    carPlayMethodChannel = FlutterMethodChannel(
+      name: carPlayMethodChannelName,
+      binaryMessenger: registrar.messenger()
+    )
+    carPlayMethodChannel?.setMethodCallHandler { [weak self] call, result in
+      self?.handleCarPlayMethod(call: call, result: result)
     }
 
-  /// Invoke play on the Flutter audio engine. Called by CarPlaySceneDelegate.
+    configureRemoteCommandCenterIfNeeded()
-  func invokePlay() {
+    requestCarPlaySnapshot()
-    playbackMethodChannel?.invokeMethod("play", arguments: nil)
-  }
-
-  /// Invoke stop on the Flutter audio engine. Called by CarPlaySceneDelegate.
-  func invokeStop() {
-    playbackMethodChannel?.invokeMethod("stop", arguments: nil)
   }
 
   @objc private func handleAudioRouteChange() {
@@ -103,6 +228,132 @@ import AVKit
     }
   }
 
+  private func handleCarPlayMethod(call: FlutterMethodCall, result: @escaping FlutterResult) {
+    switch call.method {
+    case "syncState":
+      guard let payload = call.arguments as? [String: Any] else {
+        result(
+          FlutterError(
+            code: "invalid_payload",
+            message: "Expected map payload for syncState",
+            details: nil
+          )
+        )
+        return
+      }
+
+      applyCarPlaySnapshot(payload)
+      result(nil)
+    case "getCachedState":
+      result(carPlaySnapshot.asDictionary())
+    default:
+      result(FlutterMethodNotImplemented)
+    }
+  }
+
+  private func applyCarPlaySnapshot(_ payload: [String: Any]) {
+    carPlaySnapshot = CarPlayPlaybackSnapshot(payload: payload, fallback: carPlaySnapshot)
+    updateNowPlayingInfoCenter(using: carPlaySnapshot)
+    NotificationCenter.default.post(
+      name: Self.carPlaySnapshotDidChangeNotification,
+      object: self,
+      userInfo: [Self.carPlaySnapshotUserInfoKey: carPlaySnapshot.asDictionary()]
+    )
+  }
+
+  private func updateNowPlayingInfoCenter(using snapshot: CarPlayPlaybackSnapshot) {
+    var nowPlayingInfo = MPNowPlayingInfoCenter.default().nowPlayingInfo ?? [:]
+    nowPlayingInfo[MPMediaItemPropertyTitle] = snapshot.title
+    nowPlayingInfo[MPMediaItemPropertyArtist] = snapshot.subtitle
+    nowPlayingInfo[MPMediaItemPropertyAlbumTitle] = snapshot.album
+    nowPlayingInfo[MPNowPlayingInfoPropertyIsLiveStream] = snapshot.isLive
+    nowPlayingInfo[MPNowPlayingInfoPropertyPlaybackRate] = snapshot.playbackStatus == "playing" ? 1.0 : 0.0
+    nowPlayingInfo[MPNowPlayingInfoPropertyElapsedPlaybackTime] = 0.0
+    MPNowPlayingInfoCenter.default().nowPlayingInfo = nowPlayingInfo
+
+    if #available(iOS 13.0, *) {
+      let playbackState: MPNowPlayingPlaybackState = switch snapshot.playbackStatus {
+      case "playing":
+        .playing
+      case "buffering":
+        .playing
+      default:
+        .stopped
+      }
+      MPNowPlayingInfoCenter.default().playbackState = playbackState
+    }
+  }
+
+  private func configureRemoteCommandCenterIfNeeded() {
+    if playCommandTarget != nil ||
+      togglePlayPauseCommandTarget != nil ||
+      pauseCommandTarget != nil ||
+      stopCommandTarget != nil {
+      return
+    }
+
+    let commandCenter = MPRemoteCommandCenter.shared()
+    commandCenter.changePlaybackPositionCommand.isEnabled = false
+    commandCenter.seekForwardCommand.isEnabled = false
+    commandCenter.seekBackwardCommand.isEnabled = false
+    commandCenter.nextTrackCommand.isEnabled = false
+    commandCenter.previousTrackCommand.isEnabled = false
+
+    commandCenter.playCommand.isEnabled = true
+    playCommandTarget = commandCenter.playCommand.addTarget { [weak self] _ in
+      self?.invokePlay()
+      return .success
+    }
+
+    commandCenter.togglePlayPauseCommand.isEnabled = true
+    togglePlayPauseCommandTarget = commandCenter.togglePlayPauseCommand.addTarget { [weak self] _ in
+      guard let self else {
+        return .commandFailed
+      }
+
+      switch self.carPlaySnapshot.playbackStatus {
+      case "playing", "buffering":
+        self.invokeStop()
+      default:
+        self.invokePlay()
+      }
+
+      return .success
+    }
+
+    commandCenter.pauseCommand.isEnabled = true
+    pauseCommandTarget = commandCenter.pauseCommand.addTarget { [weak self] _ in
+      self?.invokeStop()
+      return .success
+    }
+
+    commandCenter.stopCommand.isEnabled = true
+    stopCommandTarget = commandCenter.stopCommand.addTarget { [weak self] _ in
+      self?.invokeStop()
+      return .success
+    }
+  }
+
+  private func teardownRemoteCommandCenter() {
+    let commandCenter = MPRemoteCommandCenter.shared()
+    if let target = playCommandTarget {
+      commandCenter.playCommand.removeTarget(target)
+    }
+    if let target = togglePlayPauseCommandTarget {
+      commandCenter.togglePlayPauseCommand.removeTarget(target)
+    }
+    if let target = pauseCommandTarget {
+      commandCenter.pauseCommand.removeTarget(target)
+    }
+    if let target = stopCommandTarget {
+      commandCenter.stopCommand.removeTarget(target)
+    }
+    playCommandTarget = nil
+    togglePlayPauseCommandTarget = nil
+    pauseCommandTarget = nil
+    stopCommandTarget = nil
+  }
+
   private func showAirPlayPicker() {
     DispatchQueue.main.async {
       guard let rootViewController = self.activeRootViewController() else {
@@ -176,5 +427,6 @@ import AVKit
 
   deinit {
     NotificationCenter.default.removeObserver(self)
+    teardownRemoteCommandCenter()
   }
 }

ios/Runner/CarPlaySceneDelegate.swift

@@ -16,9 +16,44 @@ import UIKit
  */
 class CarPlaySceneDelegate: UIResponder, CPTemplateApplicationSceneDelegate, CPListTemplateDelegate {
 
+  private struct Snapshot {
+    var playbackStatus: String
+    var title: String
+    var subtitle: String
+    var album: String
+
+    init(playbackStatus: String, title: String, subtitle: String, album: String) {
+      self.playbackStatus = playbackStatus
+      self.title = title
+      self.subtitle = subtitle
+      self.album = album
+    }
+
+    static let `default` = Snapshot(
+      playbackStatus: "stopped",
+      title: "KRYZ Live Stream",
+      subtitle: "KRYZ Radio",
+      album: "Live"
+    )
+
+    init(payload: [String: Any]?) {
+      let base = Snapshot.default
+      let status = (payload?["playbackStatus"] as? String)?.trimmingCharacters(in: .whitespacesAndNewlines)
+      let title = (payload?["title"] as? String)?.trimmingCharacters(in: .whitespacesAndNewlines)
+      let subtitle = (payload?["subtitle"] as? String)?.trimmingCharacters(in: .whitespacesAndNewlines)
+      let album = (payload?["album"] as? String)?.trimmingCharacters(in: .whitespacesAndNewlines)
+
+      playbackStatus = (status?.isEmpty == false) ? status! : base.playbackStatus
+      self.title = (title?.isEmpty == false) ? title! : base.title
+      self.subtitle = (subtitle?.isEmpty == false) ? subtitle! : base.subtitle
+      self.album = (album?.isEmpty == false) ? album! : base.album
+    }
+  }
+
   private var carPlayInterfaceController: CPInterfaceController?
   private var listTemplate: CPListTemplate?
   private var streamItem: CPListItem?
+  private var snapshot: Snapshot = .default
 
   // MARK: - CPTemplateApplicationSceneDelegate
 
@@ -26,7 +61,10 @@ class CarPlaySceneDelegate: UIResponder, CPTemplateApplicationSceneDelegate, CPL
     _ templateApplicationScene: CPTemplateApplicationScene,
     didConnect interfaceController: CPInterfaceController
   ) {
+    appDelegate?.ensureFlutterBridgeReadyForCarPlay()
     carPlayInterfaceController = interfaceController
+    snapshot = Snapshot(payload: appDelegate?.currentCarPlaySnapshot())
+
     let rootTemplate = makeListTemplate()
     if #available(iOS 14.0, *) {
       interfaceController.setRootTemplate(rootTemplate, animated: false, completion: nil)
@@ -34,12 +72,25 @@ class CarPlaySceneDelegate: UIResponder, CPTemplateApplicationSceneDelegate, CPL
       // iOS 13 fallback: use API variant available before iOS 14.
       interfaceController.setRootTemplate(rootTemplate, animated: false)
     }
+
+    NotificationCenter.default.addObserver(
+      self,
+      selector: #selector(handleCarPlaySnapshotChanged(_:)),
+      name: AppDelegate.carPlaySnapshotDidChangeNotification,
+      object: nil
+    )
+    appDelegate?.requestCarPlaySnapshot()
   }
 
   func templateApplicationScene(
     _ templateApplicationScene: CPTemplateApplicationScene,
     didDisconnectInterfaceController interfaceController: CPInterfaceController
   ) {
+    NotificationCenter.default.removeObserver(
+      self,
+      name: AppDelegate.carPlaySnapshotDidChangeNotification,
+      object: nil
+    )
     carPlayInterfaceController = nil
     listTemplate = nil
     appDelegate?.invokeStop()
@@ -52,8 +103,8 @@ class CarPlaySceneDelegate: UIResponder, CPTemplateApplicationSceneDelegate, CPL
       .withRenderingMode(.alwaysOriginal)
 
     let item = CPListItem(
-      text: "KRYZ Live Stream",
+      text: snapshot.title,
-      detailText: "KRYZ Radio",
+      detailText: detailText(for: snapshot),
       image: icon
     )
     streamItem = item
@@ -82,10 +133,57 @@ class CarPlaySceneDelegate: UIResponder, CPTemplateApplicationSceneDelegate, CPL
     return template
   }
 
+  private func detailText(for snapshot: Snapshot) -> String {
+    let statusText: String = switch snapshot.playbackStatus {
+    case "playing":
+      "Playing"
+    case "buffering":
+      "Buffering"
+    default:
+      "Stopped"
+    }
+
+    if snapshot.subtitle.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty {
+      return statusText
+    }
+
+    return "\(snapshot.subtitle) • \(statusText)"
+  }
+
+  @objc private func handleCarPlaySnapshotChanged(_ notification: Notification) {
+    guard
+      let payload = notification.userInfo?[AppDelegate.carPlaySnapshotUserInfoKey] as? [String: Any]
+    else {
+      return
+    }
+
+    snapshot = Snapshot(payload: payload)
+    refreshTemplatesForSnapshot()
+  }
+
+  private func refreshTemplatesForSnapshot() {
+    guard let interfaceController = carPlayInterfaceController else {
+      return
+    }
+
+    if #available(iOS 14.0, *), interfaceController.topTemplate is CPNowPlayingTemplate {
+      // Preserve Now Playing navigation stack while metadata updates are flowing.
+      return
+    }
+
+    let updatedTemplate = makeListTemplate()
+    if #available(iOS 14.0, *) {
+      interfaceController.setRootTemplate(updatedTemplate, animated: false, completion: nil)
+    } else {
+      interfaceController.setRootTemplate(updatedTemplate, animated: false)
+    }
+  }
+
   // MARK: - Playback
 
   private func handleStreamItemTapped() {
     appDelegate?.invokePlay()
+    appDelegate?.requestCarPlaySnapshot()
     guard let interfaceController = carPlayInterfaceController else {
       return
     }

lib/carplay_bridge.dart

@@ -0,0 +1,77 @@
+import 'package:flutter/services.dart';
+
+import 'streaming_audio_business_object.dart';
+
+class CarPlayBridge {
+  CarPlayBridge({required StreamingAudioBusinessObject audio}) : _audio = audio;
+
+  static const MethodChannel _channel = MethodChannel(
+    'kryz_go_flutter/carplay/methods',
+  );
+
+  final StreamingAudioBusinessObject _audio;
+  bool _isStarted = false;
+
+  Future<void> start() async {
+    if (_isStarted) {
+      return;
+    }
+
+    _isStarted = true;
+    _channel.setMethodCallHandler(_handleNativeMethodCall);
+    _audio.addListener(_onAudioChanged);
+    await _pushSnapshotToNative();
+  }
+
+  Future<void> dispose() async {
+    if (!_isStarted) {
+      return;
+    }
+
+    _isStarted = false;
+    _audio.removeListener(_onAudioChanged);
+    _channel.setMethodCallHandler(null);
+  }
+
+  Map<String, dynamic> _snapshot() {
+    final String playbackStatus = switch (_audio.playbackStatus) {
+      StreamingPlaybackStatus.playing => 'playing',
+      StreamingPlaybackStatus.buffering => 'buffering',
+      StreamingPlaybackStatus.stopped => 'stopped',
+    };
+
+    return <String, dynamic>{
+      'playbackStatus': playbackStatus,
+      'isPlaying': _audio.isPlaying,
+      'isBuffering': _audio.isBuffering,
+      'isLive': true,
+      'seekable': false,
+      'title': _audio.currentTitle,
+      'subtitle': _audio.currentSubtitle,
+      'album': 'Live',
+    };
+  }
+
+  Future<dynamic> _handleNativeMethodCall(MethodCall call) async {
+    switch (call.method) {
+      case 'getStateSnapshot':
+        return _snapshot();
+      default:
+        throw MissingPluginException('Unknown CarPlay bridge method: ${call.method}');
+    }
+  }
+
+  void _onAudioChanged() {
+    _pushSnapshotToNative();
+  }
+
+  Future<void> _pushSnapshotToNative() async {
+    try {
+      await _channel.invokeMethod<void>('syncState', _snapshot());
+    } on MissingPluginException {
+      // CarPlay bridge only exists on iOS native builds.
+    } on PlatformException {
+      // Keep playback working even if native sync temporarily fails.
+    }
+  }
+}

lib/kryz_audio_handler.dart

@@ -126,6 +126,13 @@ class KryzAudioHandler extends BaseAudioHandler with SeekHandler {
     );
   }
 
+  @override
+  Future<void> pause() async {
+    // CarPlay and lock-screen transport may issue pause for live streams.
+    // Treat pause as stop to keep behavior consistent across platforms.
+    await stop();
+  }
+
   @override
   Future<void> seek(Duration position) async {
     // Live stream is intentionally non-seekable.

lib/main.dart

@@ -5,6 +5,7 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 import 'package:timezone/data/latest.dart' as tz;
 import 'app_theme_business_object.dart';
+import 'carplay_bridge.dart';
 import 'casting_business_object.dart';
 import 'live_info_business_object.dart';
 import 'live_info_panel.dart';
@@ -35,16 +36,20 @@ class MyApp extends StatefulWidget {
 class _MyAppState extends State<MyApp> {
   final StreamingAudioBusinessObject _audio = StreamingAudioBusinessObject();
   final CastingBusinessObject _casting = CastingBusinessObject();
+  late final CarPlayBridge _carPlayBridge;
 
   @override
   void initState() {
     super.initState();
+    _carPlayBridge = CarPlayBridge(audio: _audio);
     unawaited(_audio.ensureInitialized());
+    unawaited(_carPlayBridge.start());
     _casting.initialize();
   }
 
   @override
   void dispose() {
+    unawaited(_carPlayBridge.dispose());
     _casting.dispose();
     _audio.dispose();
     super.dispose();