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

import '../player/audio_handler.dart';
import '../shared/cover.dart';
import 'album_list.dart';
import 'artist_list.dart';
import 'database.dart';
import 'library_service.dart';
import 'permissions.dart';
import 'song_list.dart';
import 'song_media.dart';

/// Bibliotheks-Tab mit drei Unteransichten: alle Songs, Künstler, Alben.
/// Scan-Banner/-Fortschritt gelten für alle Unteransichten und liegen daher
/// oberhalb der [TabBarView].
class LibraryScreen extends StatelessWidget {
  const LibraryScreen({super.key});

  @override
  Widget build(BuildContext context) {
    final lib = context.watch<LibraryService>();
    return DefaultTabController(
      length: 3,
      child: Scaffold(
        appBar: AppBar(
          title: const Text('Bibliothek'),
          actions: [
            IconButton(
              tooltip: addMusicLabel,
              icon: const Icon(Icons.create_new_folder_outlined),
              onPressed: lib.scanning ? null : lib.pickFolderAndScan,
            ),
            IconButton(
              tooltip: 'Erneut scannen',
              icon: const Icon(Icons.refresh),
              onPressed: lib.scanning ? null : lib.rescan,
            ),
          ],
          bottom: const TabBar(
            tabs: [
              Tab(text: 'Alle'),
              Tab(text: 'Künstler'),
              Tab(text: 'Alben'),
            ],
          ),
        ),
        body: Column(
          children: [
            if (lib.permissionDenied)
              MaterialBanner(
                backgroundColor: Colors.red.shade900,
                content: const Text('Zugriff auf Musik verweigert. '
                    'Bitte in den Einstellungen erlauben.'),
                actions: [
                  TextButton(
                    onPressed: openMusicPermissionSettings,
                    child: const Text('Einstellungen'),
                  ),
                ],
              ),
            if (lib.scanError != null)
              MaterialBanner(
                backgroundColor: Colors.red.shade900,
                content: Text(lib.scanError!),
                actions: [
                  TextButton(
                    onPressed: lib.dismissScanError,
                    child: const Text('Verwerfen'),
                  ),
                ],
              ),
            if (lib.scanning)
              Padding(
                padding: const EdgeInsets.all(12),
                child: Column(
                  children: [
                    const LinearProgressIndicator(),
                    const SizedBox(height: 6),
                    Text(
                      'Scanne … ${lib.scanDone}'
                      '${lib.scanTotal > 0 ? ' / ${lib.scanTotal}' : ''}',
                      style: const TextStyle(color: Colors.white54, fontSize: 12),
                    ),
                  ],
                ),
              ),
            const Expanded(
              child: TabBarView(
                children: [
                  _AllSongsTab(),
                  ArtistListScreen(),
                  AlbumListScreen(),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}

/// "Alle"-Tab: zuletzt hinzugefügt + vollständige Songliste (unverändertes
/// Verhalten aus der Zeit vor der Künstler-/Alben-Aufteilung).
class _AllSongsTab extends StatelessWidget {
  const _AllSongsTab();

  @override
  Widget build(BuildContext context) {
    final db = context.read<MeloDb>();
    final lib = context.watch<LibraryService>();
    return Column(
      children: [
        StreamBuilder<List<Song>>(
          stream: db.watchRecent(limit: 10),
          builder: (context, snapshot) {
            final recent = snapshot.data ?? const [];
            if (recent.isEmpty || lib.scanning) return const SizedBox.shrink();
            return _RecentlyAdded(songs: recent);
          },
        ),
        Expanded(
          child: StreamBuilder<List<Song>>(
            stream: db.watchSongs(),
            builder: (context, snapshot) {
              if (snapshot.hasError) {
                return Center(
                  child: Text('Fehler: ${snapshot.error}',
                      style: const TextStyle(color: Colors.white54)),
                );
              }
              final songs = snapshot.data ?? const [];
              if (songs.isEmpty && !lib.scanning) {
                return const _Empty();
              }
              return SongList(songs);
            },
          ),
        ),
      ],
    );
  }
}

/// Horizontal scrollende Leiste mit den zuletzt hinzugefügten Songs.
class _RecentlyAdded extends StatelessWidget {
  const _RecentlyAdded({required this.songs});
  final List<Song> songs;

  @override
  Widget build(BuildContext context) {
    final handler = context.read<MeloAudioHandler>();
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        const Padding(
          padding: EdgeInsets.fromLTRB(16, 8, 16, 8),
          child: Text('Zuletzt hinzugefügt',
              style: TextStyle(fontSize: 18, fontWeight: FontWeight.w600)),
        ),
        SizedBox(
          height: 140,
          child: ListView.builder(
            scrollDirection: Axis.horizontal,
            padding: const EdgeInsets.symmetric(horizontal: 16),
            itemCount: songs.length,
            itemBuilder: (context, i) {
              final s = songs[i];
              return Padding(
                padding: const EdgeInsets.only(right: 12),
                child: SizedBox(
                  width: 96,
                  child: InkWell(
                    onTap: () async {
                      try {
                        await playSongs(handler, songs, i);
                      } catch (e) {
                        if (context.mounted) {
                          ScaffoldMessenger.of(context).showSnackBar(
                            SnackBar(
                                content: Text('Wiedergabe fehlgeschlagen: $e')),
                          );
                        }
                      }
                    },
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        CoverImage(
                          artUri:
                              s.coverPath != null ? Uri.file(s.coverPath!) : null,
                          size: 96,
                          radius: 8,
                        ),
                        const SizedBox(height: 4),
                        Text(
                          s.title,
                          maxLines: 1,
                          overflow: TextOverflow.ellipsis,
                          style: const TextStyle(fontSize: 12),
                        ),
                      ],
                    ),
                  ),
                ),
              );
            },
          ),
        ),
      ],
    );
  }
}

class _Empty extends StatelessWidget {
  const _Empty();

  @override
  Widget build(BuildContext context) {
    final lib = context.read<LibraryService>();
    return Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          const Icon(Icons.library_music, size: 64, color: Colors.white24),
          const SizedBox(height: 12),
          const Text('Noch keine Musik',
              style: TextStyle(color: Colors.white54)),
          const SizedBox(height: 16),
          FilledButton.icon(
            icon: const Icon(Icons.create_new_folder_outlined),
            label: Text(addMusicLabel),
            onPressed: lib.pickFolderAndScan,
          ),
        ],
      ),
    );
  }
}