import 'package:audio_service/audio_service.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../core/models.dart';
import '../data/catalog_repository.dart';
import '../offline/download_store.dart';
import 'nk_audio_handler.dart';

/// Created in main() by AudioService.init and injected with an override.
final audioHandlerProvider = Provider<NkAudioHandler>(
  (ref) => throw UnimplementedError('audioHandlerProvider must be overridden in main()'),
);

final mediaItemProvider = StreamProvider<MediaItem?>((ref) => ref.watch(audioHandlerProvider).mediaItem);

final playbackStateProvider =
    StreamProvider<PlaybackState>((ref) => ref.watch(audioHandlerProvider).playbackState);

final queueProvider = StreamProvider<List<MediaItem>>((ref) => ref.watch(audioHandlerProvider).queue);

final positionProvider = StreamProvider<Duration>((ref) => ref.watch(audioHandlerProvider).positionStream);

/// The catalog track behind the current media item, if any.
final currentTrackProvider = Provider<Track?>((ref) {
  final id = ref.watch(mediaItemProvider).value?.id;
  final catalog = ref.watch(catalogProvider).value;
  if (id == null || catalog == null) return null;
  return catalog.trackById(id);
});

final playerControllerProvider = Provider<PlayerController>((ref) => PlayerController(ref));

class PlayerController {
  PlayerController(this._ref);

  final Ref _ref;

  NkAudioHandler get _handler => _ref.read(audioHandlerProvider);

  MediaItem toMediaItem(Track t) {
    final catalog = _ref.read(catalogProvider).requireValue;
    return MediaItem(
      id: t.id,
      title: t.titleLatin,
      artist: catalog.creditLine(t),
      album: t.occasion.label,
      duration: t.duration == Duration.zero ? null : t.duration,
      artUri: t.coverUrl == null ? null : Uri.parse(t.coverUrl!),
      extras: {'url': t.audioUrl, 'coverAsset': t.coverAsset, 'occasion': t.occasion.id},
    );
  }

  Future<void> playTracks(List<Track> tracks, {int index = 0, bool shuffle = false}) async {
    await _handler.setShuffleMode(AudioServiceShuffleMode.none);
    await _handler.playQueue(tracks.map(toMediaItem).toList(), index: index);
    if (shuffle) await _handler.setShuffleMode(AudioServiceShuffleMode.all);
  }

  /// Plays downloaded songs from their saved details, so it works with no internet.
  Future<void> playDownloads(List<DownloadEntry> entries, {int index = 0}) async {
    await _handler.setShuffleMode(AudioServiceShuffleMode.none);
    await _handler.playQueue([
      for (final e in entries)
        MediaItem(
          id: e.trackId,
          title: e.title,
          artist: e.credit,
          album: e.album,
          duration: e.durationMs == 0 ? null : Duration(milliseconds: e.durationMs),
          extras: {'url': '', 'occasion': e.occasion},
        ),
    ], index: index);
  }

  void download(Iterable<Track> tracks) {
    final catalog = _ref.read(catalogProvider).requireValue;
    final store = _ref.read(downloadStoreProvider);
    for (final t in tracks) {
      store.enqueue(t, credit: catalog.creditLine(t), album: catalog.albumOf(t)?.title);
    }
  }

  Future<void> playNext(Track t) => _handler.playNext(toMediaItem(t));

  Future<void> addToQueue(Track t) => _handler.addQueueItem(toMediaItem(t));

  Future<void> togglePlay() {
    final playing = _ref.read(playbackStateProvider).value?.playing ?? false;
    return playing ? _handler.pause() : _handler.play();
  }

  Future<void> toggleShuffle() {
    final on = _ref.read(playbackStateProvider).value?.shuffleMode != AudioServiceShuffleMode.none;
    return _handler.setShuffleMode(on ? AudioServiceShuffleMode.none : AudioServiceShuffleMode.all);
  }

  /// Off -> all -> one -> off.
  Future<void> cycleRepeat() {
    final mode = _ref.read(playbackStateProvider).value?.repeatMode ?? AudioServiceRepeatMode.none;
    return _handler.setRepeatMode(switch (mode) {
      AudioServiceRepeatMode.none => AudioServiceRepeatMode.all,
      AudioServiceRepeatMode.all || AudioServiceRepeatMode.group => AudioServiceRepeatMode.one,
      AudioServiceRepeatMode.one => AudioServiceRepeatMode.none,
    });
  }
}