import 'dart:async';
import 'dart:convert';

import 'package:audio_service/audio_service.dart';
import 'package:audio_session/audio_session.dart';
import 'package:http/http.dart' as http;
import 'package:just_audio/just_audio.dart';

import 'generated/app_config.dart';
import 'live_info_business_object.dart';

class KryzAudioHandler extends BaseAudioHandler with SeekHandler {
  KryzAudioHandler() {
    mediaItem.add(_defaultMediaItem);
    _playerStateSubscription = _player.playerStateStream.listen(
      _onPlayerStateChanged,
    );
  }

  static const String streamUrl = AppConfig.streamUrl;
  static const String mediaId = 'kryz-live-stream';
  static const String _liveInfoEndpoint = AppConfig.metadataUrl ?? '';
  static const Duration _liveInfoTimeout = Duration(seconds: 8);
  static const Duration _metadataRefreshInterval = Duration(seconds: 20);

  static const MediaItem _defaultMediaItem = MediaItem(
    id: mediaId,
    title: AppConfig.defaultTitle,
    artist: AppConfig.defaultArtist,
    album: 'Live',
    extras: <String, dynamic>{
      'isLive': true,
      'seekable': false,
    },
  );

  final AudioPlayer _player = AudioPlayer();
  late final StreamSubscription<PlayerState> _playerStateSubscription;
  Timer? _metadataRefreshTimer;
  bool _isAudioSessionConfigured = false;
  bool _isSourceLoaded = false;
  bool _playRequested = false;

  Future<void> updateMetadataFromLiveInfo(LiveInfoSnapshot? snapshot) async {
    final current = snapshot?.current;
    if (current == null || current.type != 'track') {
      mediaItem.add(_defaultMediaItem);
      return;
    }

    final String subtitle = current.displaySubtitle.trim();
    mediaItem.add(
      MediaItem(
        id: mediaId,
        title: current.displayTitle,
        artist: subtitle.isEmpty ? AppConfig.defaultArtist : subtitle,
        album: 'Live',
        extras: <String, dynamic>{
          'isLive': true,
          'seekable': false,
          'starts': current.starts,
          'ends': current.ends,
          'schedulerTime': snapshot?.schedulerTime,
        },
      ),
    );
  }

  @override
  Future<void> play() async {
    _playRequested = true;
    playbackState.add(
      playbackState.value.copyWith(
        controls: const <MediaControl>[MediaControl.stop],
        systemActions: const <MediaAction>{},
        processingState: AudioProcessingState.buffering,
        playing: false,
      ),
    );

    await _configureAudioSessionIfNeeded();

    try {
      if (!_isSourceLoaded) {
        await _player.setAudioSource(
          AudioSource.uri(
            Uri.parse(streamUrl),
            tag: mediaItem.value,
          ),
        );
        _isSourceLoaded = true;
      }

      final session = await AudioSession.instance;
      await session.setActive(true);
      await _player.play();
      await _refreshMetadataFromApi();
      _startMetadataRefreshTimer();
    } catch (_) {
      _playRequested = false;
      playbackState.add(
        playbackState.value.copyWith(
          controls: const <MediaControl>[MediaControl.play],
          systemActions: const <MediaAction>{},
          processingState: AudioProcessingState.idle,
          playing: false,
        ),
      );
      rethrow;
    }
  }

  @override
  Future<void> stop() async {
    _playRequested = false;
    _isSourceLoaded = false;
    _metadataRefreshTimer?.cancel();
    _metadataRefreshTimer = null;
    await _player.stop();
    playbackState.add(
      playbackState.value.copyWith(
        controls: const <MediaControl>[MediaControl.play],
        systemActions: const <MediaAction>{},
        processingState: AudioProcessingState.idle,
        playing: false,
      ),
    );
  }

  @override
  Future<void> seek(Duration position) async {
    // Live stream is intentionally non-seekable.
  }

  @override
  Future<void> playFromMediaId(String mediaId, [Map<String, dynamic>? extras]) {
    return play();
  }

  @override
  Future<void> playFromSearch(String query, [Map<String, dynamic>? extras]) {
    return play();
  }

  Future<void> dispose() async {
    _metadataRefreshTimer?.cancel();
    await _playerStateSubscription.cancel();
    await _player.dispose();
  }

  Future<void> _configureAudioSessionIfNeeded() async {
    if (_isAudioSessionConfigured) {
      return;
    }

    final session = await AudioSession.instance;
    await session.configure(const AudioSessionConfiguration.music());
    _isAudioSessionConfigured = true;
  }

  void _onPlayerStateChanged(PlayerState state) {
    final AudioProcessingState processingState = switch (state.processingState) {
      ProcessingState.idle => AudioProcessingState.idle,
      ProcessingState.loading => AudioProcessingState.loading,
      ProcessingState.buffering => AudioProcessingState.buffering,
      ProcessingState.ready => AudioProcessingState.ready,
      ProcessingState.completed => AudioProcessingState.completed,
    };

    final bool isPlaying = state.playing && state.processingState == ProcessingState.ready;
    final bool isBuffering = (state.playing && state.processingState != ProcessingState.ready) ||
        (_playRequested && !state.playing && state.processingState != ProcessingState.completed);

    playbackState.add(
      playbackState.value.copyWith(
        controls: <MediaControl>[
          if (isPlaying || isBuffering) MediaControl.stop else MediaControl.play,
        ],
        systemActions: const <MediaAction>{},
        processingState: isBuffering ? AudioProcessingState.buffering : processingState,
        playing: isPlaying,
      ),
    );

    if (isPlaying || isBuffering) {
      _startMetadataRefreshTimer();
    } else {
      _metadataRefreshTimer?.cancel();
      _metadataRefreshTimer = null;
    }
  }

  void _startMetadataRefreshTimer() {
    if (_metadataRefreshTimer != null) {
      return;
    }

    _metadataRefreshTimer = Timer.periodic(_metadataRefreshInterval, (_) {
      _refreshMetadataFromApi();
    });
  }

  Future<void> _refreshMetadataFromApi() async {
    try {
      final response = await http
          .get(Uri.parse(_liveInfoEndpoint))
          .timeout(_liveInfoTimeout);
      if (response.statusCode < 200 || response.statusCode >= 300) {
        return;
      }

      final dynamic decoded = jsonDecode(response.body);
      if (decoded is! Map<String, dynamic>) {
        return;
      }

      final snapshot = LiveInfoSnapshot.fromJson(decoded);
      await updateMetadataFromLiveInfo(snapshot);
    } catch (_) {
      // Keep existing metadata if live-info fetch fails.
    }
  }
}