import 'package:audio_service/audio_service.dart';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

import '../library/category_service.dart';
import '../library/database.dart';
import '../library/playlist_service.dart';
import '../library/song_media.dart';
import '../player/audio_handler.dart';
import '../settings/app_settings.dart';
import '../shared/cover.dart';
import '../shared/lauf_balken.dart';
import '../shared/theme.dart';

/// Playlist-Detailansicht: Songs anzeigen, per Drag & Drop umsortieren, entfernen.
class PlaylistDetailScreen extends StatelessWidget {
  const PlaylistDetailScreen({super.key, required this.playlist});
  final Playlist playlist;

  @override
  Widget build(BuildContext context) {
    final db = context.read<MeloDb>();
    final service = context.read<PlaylistService>();
    return Scaffold(
      appBar: AppBar(title: Text(playlist.name)),
      body: StreamBuilder<List<Song>>(
        stream: db.watchPlaylistSongs(playlist.id),
        builder: (context, snapshot) {
          if (snapshot.hasError) {
            return Center(
              child: Text('Fehler: ${snapshot.error}',
                  style: const TextStyle(color: MeloTheme.text2)),
            );
          }
          final songs = snapshot.data ?? const [];
          if (songs.isEmpty) {
            return const Center(
              child: Text('Playlist ist leer — füge Songs aus der Bibliothek hinzu',
                  style: TextStyle(color: MeloTheme.text2)),
            );
          }
          return ReorderableListView.builder(
            itemCount: songs.length,
            onReorderItem: (oldIndex, newIndex) {
              final reordered = List<Song>.from(songs);
              final moved = reordered.removeAt(oldIndex);
              reordered.insert(newIndex, moved);
              service.reorderAll(playlist.id, reordered.map((s) => s.id).toList());
            },
            itemBuilder: (context, i) => _Zeile(
              key: ValueKey(songs[i].id),
              song: songs[i],
              alleSongs: songs,
              index: i,
              onEntfernen: () =>
                  service.removeSongFromPlaylist(playlist.id, songs[i].id),
            ),
          );
        },
      ),
    );
  }
}

/// Eine Zeile der Wiedergabeliste.
///
/// Nicht [SongZeile]: hier steht rechts „Aus Playlist entfernen" statt Herz
/// und Menü. Die Lauf-Markierung ist dieselbe — der Nutzer soll dasselbe
/// Zeichen sehen wie in der Bibliothek.
class _Zeile extends StatelessWidget {
  const _Zeile({
    super.key,
    required this.song,
    required this.alleSongs,
    required this.index,
    required this.onEntfernen,
  });

  final Song song;
  final List<Song> alleSongs;
  final int index;
  final VoidCallback onEntfernen;

  @override
  Widget build(BuildContext context) {
    final handler = context.read<MeloAudioHandler>();
    final categories = context.watch<CategoryService>();
    final settings = context.watch<AppSettings>();
    final cover = categories.coverFor(song,
        groupByCategory: settings.groupCoversByCategory);
    return StreamBuilder<MediaItem?>(
      stream: handler.mediaItem,
      initialData: handler.mediaItem.valueOrNull,
      builder: (context, laufSnap) {
        final markiert = istAmLaufen(laufSnap.data, song.id);
        return StreamBuilder<PlaybackState>(
          stream: markiert ? handler.playbackState : null,
          initialData: handler.playbackState.valueOrNull,
          builder: (context, zustandSnap) => ListTile(
            leading: LaufMarkierung(
              markiert: markiert,
              spielt: markiert && (zustandSnap.data?.playing ?? false),
              radius: 6,
              child: CoverImage(
                artUri: cover != null ? Uri.file(cover) : null,
                size: 48,
                radius: 6,
              ),
            ),
            title: Text(
              song.title,
              maxLines: 1,
              overflow: TextOverflow.ellipsis,
              style: markiert
                  ? const TextStyle(
                      color: MeloTheme.red, fontWeight: FontWeight.w600)
                  : null,
            ),
            subtitle: Text(song.artist ?? 'Unbekannt',
                maxLines: 1, overflow: TextOverflow.ellipsis),
            trailing: IconButton(
              tooltip: 'Aus Playlist entfernen',
              icon: const Icon(Icons.remove_circle_outline),
              onPressed: onEntfernen,
            ),
            onTap: () async {
              final messenger = ScaffoldMessenger.of(context);
              try {
                final uebersprungen = await playSongs(
                  handler,
                  alleSongs,
                  index,
                  coverOf: (s) => categories.coverFor(s,
                      groupByCategory: settings.groupCoversByCategory),
                );
                if (uebersprungen > 0) {
                  messenger.showSnackBar(
                    SnackBar(content: Text(offlineHinweis(uebersprungen))),
                  );
                }
              } catch (e) {
                messenger.showSnackBar(
                  SnackBar(content: Text('Wiedergabe fehlgeschlagen: $e')),
                );
              }
            },
          ),
        );
      },
    );
  }
}