import 'dart:io';

import 'package:just_audio/just_audio.dart';
import 'package:path_provider/path_provider.dart';
import 'package:permission_handler/permission_handler.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';
import '../models/song.dart';
import '../database/db_helper.dart';
import '../utils/audio_validator.dart';
import 'id3_reader.dart';
import 'melo_logger.dart';

class MusikScanner {
  static final MusikScanner _instanz = MusikScanner._();
  factory MusikScanner() => _instanz;
  MusikScanner._();

  final DbHelper _db = DbHelper();
  int _neueSongs = 0;

  int get anzahlNeueSongs => _neueSongs;

  Future<bool> frageSpeicherZugriff() async {
    // App-interner Speicher (Cloud-Downloads) benötigt NIE Berechtigungen
    if (Platform.isIOS) return true;

    if (Platform.isAndroid) {
      // Android 13+: READ_MEDIA_AUDIO
      var status = await Permission.audio.status;
      if (!status.isGranted) status = await Permission.audio.request();
      if (status.isGranted) return true;

      // Fallback für Android 10 und älter
      var storageStatus = await Permission.storage.status;
      if (!storageStatus.isGranted) storageStatus = await Permission.storage.request();
      return storageStatus.isGranted;
    }

    return true;
  }

  Future<List<Song>> scanneMusikOrdner() async {
    _neueSongs = 0;
    final gefunden = <Song>[];
    final pfade = await _sammleMusikPfade();

    final player = AudioPlayer();

    for (final pfad in pfade) {
      try {
        final file = File(pfad);
        if (!await file.exists()) continue;
        final stat = await file.stat();
        final tags = Id3Reader.lesen(pfad);

        // ── Magic-Byte-Prüfung ──
        final istKorrupt = !hatValideMagicBytes(file);
        if (istKorrupt) {
          MeloLogger().fehler('magic_bytes_scan', 'Ungültiger Audio-Header: $pfad');
        }

        // Cover-Bytes als Bilddatei speichern
        String? coverPfad;
        if (tags['cover'] != null && tags['cover'] is List<int>) {
          final bytes = tags['cover'] as List<int>;
          if (bytes.isNotEmpty) {
            try {
              final docDir = await getApplicationDocumentsDirectory();
              final coversDir = Directory('${docDir.path}/covers');
              if (!await coversDir.exists()) await coversDir.create(recursive: true);
              final fileHash = pfad.hashCode.abs();
              final coverFile = File('${coversDir.path}/cover_$fileHash.jpg');
              await coverFile.writeAsBytes(bytes);
              coverPfad = coverFile.path;
            } catch (e) {
              MeloLogger().fehler('cover_speichern', e);
            }
          }
        }

        gefunden.add(Song(
          titel: (tags['titel'] as String).isNotEmpty ? tags['titel'] : _dateiNameOhneEndung(pfad),
          kuenstler: (tags['kuenstler'] as String).isNotEmpty ? tags['kuenstler'] : 'Unbekannt',
          album: tags['album'] ?? '',
          dauerSekunden: await _ermittleDauer(player, pfad),
          dateiPfad: pfad,
          coverPfad: coverPfad,
          groesseBytes: stat.size,
          istHeruntergeladen: true,
          istKorrupt: istKorrupt,
          downloadQuelle: 'local',
        ));
      } catch (e) {
        MeloLogger().fehler('scanner_datei', e);
        continue;
      }
    }

    try { await player.dispose(); } catch (_) {}

    // In DB speichern
    final vorhandene = await _db.alleSongs();
    final vorhandenePfade = vorhandene.map((s) => s.dateiPfad).toSet();

    final neue = gefunden.where((s) => !vorhandenePfade.contains(s.dateiPfad)).toList();
    if (neue.isNotEmpty) {
      await _db.songsEinfuegen(neue);
      _neueSongs = neue.length;
    }

    // ── YouTube-Quell-URLs für Songs ohne ytUrl nachschlagen ──
    await _sucheYtUrls();

    return gefunden;
  }

  Future<List<String>> _sammleMusikPfade() async {
    final pfade = <String>{};
    // 1. PRIMÄR: App-interner + Downloads-Ordner
    try {
      final appDir = await getApplicationDocumentsDirectory();
      final internDir = Directory('${appDir.path}/music');
      if (await internDir.exists()) await _durchsucheOrdner(internDir, pfade);

      // Downloads/Melo (für Dateimanager sichtbar)
      if (Platform.isAndroid) {
        final dlDir = await getDownloadsDirectory();
        if (dlDir != null) {
          final meloDir = Directory('${dlDir.path}/Melo');
          if (await meloDir.exists()) await _durchsucheOrdner(meloDir, pfade);
        }
      }
    } catch (e) {
      MeloLogger().fehler('scanner_intern_pfad', e);
    }

    // 2. Externe System-Ordner (nur Android)
    if (Platform.isAndroid) {
      final ordner = <String>[
        '/storage/emulated/0/Music',
        '/storage/emulated/0/Download',
        '/storage/emulated/0/Musik',
        '/storage/emulated/0/Downloads',
        '/sdcard/Music',
        '/sdcard/Download',
      ];

      try {
        final extern = await getExternalStorageDirectory();
        if (extern != null) ordner.add(extern.path);
      } catch (_) {}

      for (final ord in ordner) {
        try {
          final dir = Directory(ord);
          if (await dir.exists()) {
            await _durchsucheOrdner(dir, pfade);
          }
        } catch (e) {
          MeloLogger().fehler('scanner_ordner_zugriff_${ord.split('/').last}', e);
        }
      }
    }

    return pfade.toList();
  }

  Future<void> _durchsucheOrdner(Directory dir, Set<String> pfade, {int tiefe = 0}) async {
    if (tiefe > 4) return;
    try {
      final stream = dir.list(followLinks: false);
      await for (final entity in stream.handleError((_) {})) {
        if (entity is File) {
          final ext = entity.path.toLowerCase();
          if (ext.endsWith('.mp3') || ext.endsWith('.m4a') ||
              ext.endsWith('.flac') || ext.endsWith('.wav') ||
              ext.endsWith('.aac') || ext.endsWith('.ogg')) {
            pfade.add(entity.path);
          }
        } else if (entity is Directory) {
          await _durchsucheOrdner(entity, pfade, tiefe: tiefe + 1);
        }
      }
    } catch (e) {
      MeloLogger().fehler('scanner_durchsuchen_fehler', '$dir: $e');
    }
  }

  Future<int> _ermittleDauer(AudioPlayer player, String pfad) async {
    try {
      await player.setFilePath(pfad).timeout(const Duration(milliseconds: 1500));
      final dauer = player.duration;
      return dauer?.inSeconds ?? 0;
    } catch (e) {
      try { await player.stop(); } catch (_) {}
      return 0;
    }
  }

  String _dateiNameOhneEndung(String pfad) {
    final name = pfad.split('/').last;
    final dot = name.lastIndexOf('.');
    return dot > 0 ? name.substring(0, dot) : name;
  }

  /// Sucht YouTube-Quell-URLs für Songs ohne ytUrl (max 50 pro Scan, 1/s Rate-Limit)
  Future<void> _sucheYtUrls() async {
    const maxSuchanfragen = 50;
    const suchUrlBasis = 'https://yt.baka-net.de/api/search';

    final songsOhneUrl = await _db.songsOhneYtUrl(limit: maxSuchanfragen);
    if (songsOhneUrl.isEmpty) return;

    int gefunden = 0;
    for (final song in songsOhneUrl) {
      if (gefunden >= maxSuchanfragen) break;

      try {
        final query = '${song.kuenstler} ${song.titel}';
        final url = '$suchUrlBasis?q=${Uri.encodeQueryComponent(query)}';

        final antwort = await http.get(Uri.parse(url)).timeout(
          const Duration(seconds: 10),
        );

        if (antwort.statusCode == 200) {
          final daten = jsonDecode(antwort.body);
          if (daten is List && daten.isNotEmpty) {
            final erstes = daten[0];
            final ytUrl = erstes['url'] as String?;
            if (ytUrl != null && ytUrl.isNotEmpty) {
              await _db.ytUrlAktualisieren(song.id!, ytUrl);
              gefunden++;
              MeloLogger().zustand('yt_suche_treffer', {
                'song_id': song.id,
                'titel': song.titel,
                'yt_url': ytUrl,
              });
            }
          }
        }
      } catch (e) {
        MeloLogger().fehler('yt_suche_fehler', '${song.titel}: $e');
      }

      // Rate-Limit: 1 Anfrage pro Sekunde
      await Future.delayed(const Duration(seconds: 1));
    }

    if (gefunden > 0) {
      MeloLogger().zustand('yt_suche_abschluss', {'gefunden': gefunden});
    }
  }
}