AudiOhm/frontend/lib/presentation/providers/music_provider.dart

/// Music Provider - Player state management
library;

import 'dart:async';

import 'package:flutter/foundation.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:just_audio/just_audio.dart';

import '../../../domain/entities/track.dart';

/// Player state
class PlayerState {
  final List<Track> queue;
  final int currentIndex;
  final bool isPlaying;
  final Duration position;
  final Duration duration;
  final bool isLoading;
  final String? errorMessage;

  const PlayerState({
    this.queue = const [],
    this.currentIndex = -1,
    this.isPlaying = false,
    this.position = Duration.zero,
    this.duration = Duration.zero,
    this.isLoading = false,
    this.errorMessage,
  });

  Track? get currentTrack =>
      currentIndex >= 0 && currentIndex < queue.length
          ? queue[currentIndex]
          : null;

  PlayerState copyWith({
    List<Track>? queue,
    int? currentIndex,
    bool? isPlaying,
    Duration? position,
    Duration? duration,
    bool? isLoading,
    String? errorMessage,
  }) {
    return PlayerState(
      queue: queue ?? this.queue,
      currentIndex: currentIndex ?? this.currentIndex,
      isPlaying: isPlaying ?? this.isPlaying,
      position: position ?? this.position,
      duration: duration ?? this.duration,
      isLoading: isLoading ?? this.isLoading,
      errorMessage: errorMessage,
    );
  }
}

/// Player notifier
class PlayerNotifier extends StateNotifier<PlayerState> {
  PlayerNotifier() : super(const PlayerState()) {
    _player = AudioPlayer();
    _subscriptions = [];
    _init();
  }

  late final AudioPlayer _player;
  final List<StreamSubscription> _subscriptions = [];

  void _init() {
    // Subscribe to position stream and store subscription
    _subscriptions.add(_player.positionStream.listen((position) {
      state = state.copyWith(position: position);
    }));

    // Subscribe to duration stream and store subscription
    _subscriptions.add(_player.durationStream.listen((duration) {
      state = state.copyWith(duration: duration ?? Duration.zero);
    }));

    // Subscribe to player state stream and store subscription
    _subscriptions.add(_player.playerStateStream.listen((playerState) {
      state = state.copyWith(
        isPlaying: playerState.playing,
        isLoading: playerState.processingState == ProcessingState.loading,
      );
    }));
  }

  Future<void> loadTrack(Track track) async {
    state = state.copyWith(isLoading: true, errorMessage: null);

    try {
      // Validate audio URL exists
      final streamUrl = track.audioUrl;

      if (streamUrl == null || streamUrl.isEmpty) {
        throw Exception('No audio URL available for track: ${track.title}');
      }

      await _player.setUrl(streamUrl);

      if (state.queue.isEmpty) {
        state = state.copyWith(queue: [track], currentIndex: 0);
      }

      // Clear error and loading state on success
      state = state.copyWith(isLoading: false, errorMessage: null);
    } on PlayerException catch (e) {
      // Specific audio player errors
      debugPrint('Player error loading track: ${e.message}');
      state = state.copyWith(
        isLoading: false,
        errorMessage: 'Unable to play this track. Please try another.',
      );
    } catch (e) {
      // Network or other errors
      debugPrint('Error loading track: $e');
      state = state.copyWith(
        isLoading: false,
        errorMessage: 'An error occurred while loading the track.',
      );
    }
  }

  Future<void> play() async {
    if (state.currentTrack != null) {
      await _player.play();
      state = state.copyWith(isPlaying: true);
    }
  }

  Future<void> pause() async {
    await _player.pause();
    state = state.copyWith(isPlaying: false);
  }

  /// Convenience method to toggle play/pause
  Future<void> togglePlay() async {
    if (state.isPlaying) {
      await pause();
    } else {
      await play();
    }
  }

  Future<void> seek(Duration position) async {
    await _player.seek(position);
  }

  Future<void> next() async {
    if (state.currentIndex < state.queue.length - 1) {
      final nextTrack = state.queue[state.currentIndex + 1];
      await loadTrack(nextTrack);
      state = state.copyWith(currentIndex: state.currentIndex + 1);
      await play();
    }
  }

  Future<void> previous() async {
    if (state.currentIndex > 0) {
      final previousTrack = state.queue[state.currentIndex - 1];
      await loadTrack(previousTrack);
      state = state.copyWith(currentIndex: state.currentIndex - 1);
      await play();
    }
  }

  void setQueue(List<Track> tracks, {int startIndex = 0}) {
    state = state.copyWith(
      queue: tracks,
      currentIndex: startIndex,
    );
  }

  void addToQueue(Track track) {
    final newQueue = [...state.queue, track];
    state = state.copyWith(queue: newQueue);
  }

  void removeFromQueue(int index) {
    if (index >= 0 && index < state.queue.length) {
      final newQueue = [...state.queue]..removeAt(index);
      state = state.copyWith(queue: newQueue);
    }
  }

  @override
  void dispose() {
    // Cancel all stream subscriptions to prevent memory leaks
    for (final subscription in _subscriptions) {
      subscription.cancel();
    }
    _player.dispose();
    super.dispose();
  }
}

/// Player provider
final playerProvider =
    StateNotifierProvider<PlayerNotifier, PlayerState>((ref) {
  return PlayerNotifier();
});

/// Current track provider
final currentTrackProvider = Provider<Track?>((ref) {
  return ref.watch(playerProvider).currentTrack;
});

/// Queue view data class
class QueueViewData {
  final Track? currentTrack;
  final List<Track> queue;
  final int currentIndex;
  final bool isPlaying;

  const QueueViewData({
    required this.currentTrack,
    required this.queue,
    required this.currentIndex,
    required this.isPlaying,
  });

  /// Get upcoming tracks (after current)
  List<Track> get nextTracks {
    if (currentIndex < 0 || currentIndex >= queue.length - 1) {
      return [];
    }
    return queue.sublist(currentIndex + 1);
  }

  /// Get previously played tracks (before current)
  List<Track> get previousTracks {
    if (currentIndex <= 0) {
      return [];
    }
    return queue.sublist(0, currentIndex);
  }

  /// Check if queue has tracks
  bool get hasQueue => queue.isNotEmpty;

  /// Check if there are upcoming tracks
  bool get hasNextTracks => nextTracks.isNotEmpty;

  /// Check if there are previous tracks
  bool get hasPreviousTracks => previousTracks.isNotEmpty;

  /// Get total queue count excluding current
  int get queueCount => queue.length - 1;
}

/// Queue view provider
final queueProvider = Provider<QueueViewData>((ref) {
  final playerState = ref.watch(playerProvider);
  return QueueViewData(
    currentTrack: playerState.currentTrack,
    queue: playerState.queue,
    currentIndex: playerState.currentIndex,
    isPlaying: playerState.isPlaying,
  );
});