import 'dart:async';

import 'package:flutter/material.dart';
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 'casting_business_object.dart';
import 'live_info_business_object.dart';
import 'live_info_panel.dart';
import 'streaming_audio_business_object.dart';

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  tz.initializeTimeZones();
  runApp(const MyApp());

  // Keep startup non-blocking so UI can render even if background media
  // services are initializing after an Android Auto cold start.
  unawaited(
    SystemChrome.setPreferredOrientations([
      DeviceOrientation.portraitUp,
      DeviceOrientation.portraitDown,
    ]),
  );
}

class MyApp extends StatefulWidget {
  const MyApp({super.key});

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  final StreamingAudioBusinessObject _audio = StreamingAudioBusinessObject();
  final CastingBusinessObject _casting = CastingBusinessObject();

  @override
  void initState() {
    super.initState();
    unawaited(_audio.ensureInitialized());
    _casting.initialize();
  }

  @override
  void dispose() {
    _casting.dispose();
    _audio.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'KRYZ Go!',
      theme: AppThemeBusinessObject.lightTheme(),
      darkTheme: AppThemeBusinessObject.darkTheme(),
      themeMode: ThemeMode.system,
      home: MainPage(audio: _audio, casting: _casting),
      debugShowCheckedModeBanner: false,
    );
  }
}

class MainPage extends StatefulWidget {
  const MainPage({super.key, required this.audio, required this.casting});

  final StreamingAudioBusinessObject audio;
  final CastingBusinessObject casting;

  @override
  State<MainPage> createState() => _MainPageState();
}

class _MainPageState extends State<MainPage> {
  StreamingAudioBusinessObject get _audio => widget.audio;
  CastingBusinessObject get _casting => widget.casting;
  final LiveInfoBusinessObject _liveInfo = LiveInfoBusinessObject();
  static const List<int> _intervalOptions = <int>[5, 10, 15, 30, 60];
  bool _castStreamStartedForActiveSession = false;
  bool _isStartingCastStream = false;
  bool _pendingRemotePlay = false;

  bool get _usesExternalCastPlayback =>
      _casting.isConnected && defaultTargetPlatform == TargetPlatform.android;

  bool get _isIosAirPlay => defaultTargetPlatform == TargetPlatform.iOS;

  bool get _isUsingRemotePlayback => _usesExternalCastPlayback;

  bool get _isPlaybackStopped {
    if (_isUsingRemotePlayback) {
      return _casting.isStopped ||
          _casting.playbackStatus == CastingPlaybackStatus.unknown;
    }

    return _audio.isStopped;
  }

  bool get _isPlaybackPlaying {
    if (_isUsingRemotePlayback) {
      return _casting.isPlaying;
    }

    return _audio.isPlaying;
  }

  bool get _isPlaybackBuffering {
    if (_isUsingRemotePlayback) {
      return _casting.isBuffering;
    }

    return _audio.isBuffering;
  }

  String _playbackStatusLabel() {
    if (_isPlaybackBuffering) {
      return 'Buffering...';
    }

    if (_isPlaybackPlaying) {
      return 'Playing';
    }

    return 'Stopped';
  }

  static const _playbackChannel = MethodChannel(
    'kryz_go_flutter/playback/methods',
  );

  @override
  void initState() {
    super.initState();
    _audio.addListener(_handleAudioStateChanged);
    _casting.addListener(_handleCastingStateChanged);
    _liveInfo.addListener(_handleLiveInfoChanged);
    _liveInfo.start();
    _playbackChannel.setMethodCallHandler(_handlePlaybackMethodCall);
  }

  Future<void> _handlePlaybackMethodCall(MethodCall call) async {
    switch (call.method) {
      case 'play':
        await _play();
      case 'stop':
        await _stop();
    }
  }

  void _handleAudioStateChanged() {
    if (!mounted) {
      return;
    }

    setState(() {
      // Rebuild when playback state changes from the player.
    });
  }

  void _handleLiveInfoChanged() {
    _audio.updateMetadataFromLiveInfo(_liveInfo.snapshot);

    if (!mounted) {
      return;
    }

    setState(() {
      // Rebuild when live metadata updates from the polling API.
    });
  }

  void _handleCastingStateChanged() {
    if (_usesExternalCastPlayback &&
        (!_castStreamStartedForActiveSession || _pendingRemotePlay) &&
        !_isStartingCastStream) {
      _startCastingLiveStream();
    }

    if (!_usesExternalCastPlayback) {
      _castStreamStartedForActiveSession = false;
      _isStartingCastStream = false;
      _pendingRemotePlay = false;
    }

    if (!mounted) {
      return;
    }

    setState(() {
      // Rebuild when cast state changes from the native platforms.
    });
  }

  Future<void> _startCastingLiveStream() async {
    _isStartingCastStream = true;

    try {
      await _casting.startCastingLiveStream(
        streamUrl: _audio.streamUrl,
        title: _audio.currentTitle,
        subtitle: _audio.currentSubtitle,
      );

      _castStreamStartedForActiveSession = true;
      _pendingRemotePlay = false;

      if (_usesExternalCastPlayback && !_audio.isStopped) {
        await _audio.stop();
      }
    } catch (_) {
      _castStreamStartedForActiveSession = false;
      // State is already updated by the casting business object.
    } finally {
      _isStartingCastStream = false;
    }
  }

  Future<void> _play() async {
    if (_usesExternalCastPlayback) {
      if (_casting.isPlaying || _isStartingCastStream) {
        return;
      }

      await _startCastingLiveStream();
      return;
    }

    if (_usesExternalCastPlayback &&
        _casting.status == CastingStatus.connecting) {
      _pendingRemotePlay = true;
      return;
    }

    await _audio.play();
  }

  Future<void> _stop() async {
    if (_usesExternalCastPlayback) {
      await _casting.stopPlayback();
      return;
    }

    await _audio.stop();
  }

  Future<void> _toggleCasting() async {
    if (_casting.isConnected) {
      await _casting.disconnect();
      return;
    }

    await _casting.showDevicePicker();
  }

  String _castingLabel() {
    final idleLabel = _isIosAirPlay ? 'AirPlay' : 'Cast';
    final connectingLabel = _isIosAirPlay ? 'AirPlay...' : 'Casting...';
    final errorLabel = _isIosAirPlay ? 'AirPlay Error' : 'Cast Error';
    final unavailableLabel = _isIosAirPlay ? 'No AirPlay' : 'No Cast';

    switch (_casting.status) {
      case CastingStatus.idle:
        return idleLabel;
      case CastingStatus.connecting:
        return connectingLabel;
      case CastingStatus.connected:
        final deviceName = _casting.connectedDeviceName;
        if (deviceName != null && deviceName.isNotEmpty) {
          return 'On $deviceName';
        }
        return _isIosAirPlay ? 'AirPlaying' : 'Casting';
      case CastingStatus.error:
        return errorLabel;
      case CastingStatus.unavailable:
        return unavailableLabel;
    }
  }

  IconData _castingIcon() {
    if (_isIosAirPlay) {
      return Icons.airplay_rounded;
    }

    return _casting.isConnected
        ? Icons.cast_connected_rounded
        : Icons.cast_rounded;
  }

  @override
  void dispose() {
    _audio.removeListener(_handleAudioStateChanged);
    _casting.removeListener(_handleCastingStateChanged);
    _liveInfo.removeListener(_handleLiveInfoChanged);
    _liveInfo.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final themeColors = AppThemeBusinessObject.colorsFor(context);
    final theme = Theme.of(context);

    return Scaffold(
      body: DecoratedBox(
        decoration: BoxDecoration(
          gradient: LinearGradient(
            begin: Alignment.topLeft,
            end: Alignment.bottomRight,
            colors: [
              themeColors.scaffoldGradientStart,
              themeColors.scaffoldGradientEnd,
            ],
          ),
        ),
        child: SafeArea(
          child: Padding(
            padding: const EdgeInsets.all(12),
            child: Column(
              children: [
                Container(
                  width: double.infinity,
                  padding: const EdgeInsets.all(14),
                  decoration: BoxDecoration(
                    color: themeColors.shellSurface,
                    borderRadius: BorderRadius.circular(24),
                    border: Border.all(color: themeColors.shellBorder),
                    boxShadow: [
                      BoxShadow(
                        color: themeColors.controlsShadow,
                        blurRadius: 18,
                        offset: const Offset(0, 10),
                      ),
                    ],
                  ),
                  child: Row(
                    children: [
                      ClipRRect(
                        borderRadius: BorderRadius.circular(18),
                        child: Image.asset(
                          'assets/icon/app_icon.png',
                          width: 72,
                          height: 72,
                          fit: BoxFit.cover,
                        ),
                      ),
                      const SizedBox(width: 14),
                      Expanded(
                        child: Text(
                          'KRYZ Go!',
                          textAlign: TextAlign.center,
                          style: theme.textTheme.headlineMedium?.copyWith(
                            fontWeight: FontWeight.w900,
                            letterSpacing: 0.4,
                            color: themeColors.statusText,
                          ),
                        ),
                      ),
                      const SizedBox(width: 86),
                    ],
                  ),
                ),
                const SizedBox(height: 12),
                Expanded(
                  child: LiveInfoPanel(
                    liveInfo: _liveInfo,
                    themeColors: themeColors,
                    intervalOptions: _intervalOptions,
                  ),
                ),
                const SizedBox(height: 12),
                Container(
                  width: double.infinity,
                  padding: const EdgeInsets.symmetric(
                    horizontal: 16,
                    vertical: 14,
                  ),
                  decoration: BoxDecoration(
                    borderRadius: BorderRadius.circular(24),
                    gradient: LinearGradient(
                      begin: Alignment.topLeft,
                      end: Alignment.bottomRight,
                      colors: [
                        themeColors.controlsGradientStart,
                        themeColors.controlsGradientEnd,
                      ],
                    ),
                    boxShadow: [
                      BoxShadow(
                        color: themeColors.controlsShadow,
                        blurRadius: 14,
                        offset: const Offset(0, 6),
                      ),
                    ],
                  ),
                  child: Wrap(
                    alignment: WrapAlignment.center,
                    crossAxisAlignment: WrapCrossAlignment.center,
                    spacing: 12,
                    runSpacing: 12,
                    children: [
                      ElevatedButton.icon(
                        onPressed: _isPlaybackStopped ? _play : null,
                        icon: const Icon(Icons.play_arrow_rounded),
                        label: const Text('Play'),
                      ),
                      ElevatedButton.icon(
                        onPressed: _isPlaybackStopped ? null : _stop,
                        icon: const Icon(Icons.stop_rounded),
                        label: const Text('Stop'),
                      ),
                      ElevatedButton.icon(
                        onPressed:
                            _casting.status == CastingStatus.connecting ||
                                _casting.status == CastingStatus.unavailable
                            ? null
                            : _toggleCasting,
                        icon: Icon(_castingIcon()),
                        label: Text(_castingLabel()),
                      ),
                      Text(
                        _playbackStatusLabel(),
                        style: theme.textTheme.titleSmall?.copyWith(
                          fontWeight: FontWeight.w700,
                          color: themeColors.statusText,
                        ),
                      ),
                    ],
                  ),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}