import 'dart:convert';
import 'dart:io';
import 'package:flutter/foundation.dart';
import 'package:http/http.dart' as http;
import '../config/app_config.dart';
import '../services/auth_service.dart';
import '../services/melo_logger.dart';

/// Verbindungsstatus der Cloud
enum CloudStatus { verbinde, verbunden, fehler }

/// Cloud-Sync Service für Melo Registry (v3 — vollständiges Sync-System)
/// Authentifizierung via Baka-Auth JWT-Token
///
/// ## Konfliktauflösung: Last-Write-Wins (LWW)
/// Bei Sync-Konflikten (Client und Server haben beide geändert) gewinnt der
/// Eintrag mit dem neueren `updated_at`-Timestamp. Strategie:
/// 1. `syncChanges(since)` lädt serverseitige Änderungen seit letztem Sync.
/// 2. Client vergleicht `updated_at` mit lokalem Stand — Server gewinnt bei Gleichstand.
/// 3. Lokale Änderungen werden danach per `syncAll()` hochgeladen.
/// Merge-Strategie wird NICHT unterstützt (kein 3-Way-Merge) — es gewinnt immer
/// der jüngste Timestamp.
class CloudService extends ChangeNotifier {
  /// Injizierbarer HTTP-Client (Tests: package:http/testing.dart MockClient).
  CloudService({http.Client? client}) : _client = client ?? http.Client();

  final http.Client _client;

  static String get _base => AppConfig.cloudUrl;

  CloudStatus _status = CloudStatus.verbinde;
  bool _verbindungGestartet = false;

  /// Aktueller Verbindungsstatus der Cloud
  CloudStatus get status => _status;

  /// Ob die Cloud-Verbindung steht
  bool get istVerbunden => _status == CloudStatus.verbunden;

  /// Ob bereits ein Verbindungsversuch gestartet wurde (auch wenn er läuft)
  bool get verbindungGestartet => _verbindungGestartet;

  /// Anzeigetext für den Verbindungsstatus
  String get statusText {
    switch (_status) {
      case CloudStatus.verbinde:
        return 'Verbinde...';
      case CloudStatus.verbunden:
        return 'Verbunden';
      case CloudStatus.fehler:
        return 'Keine Verbindung';
    }
  }

  /// Stellt die Cloud-Verbindung her (Login + Status-Check) und benachrichtigt
  /// Listener über den neuen Status. Wird beim App-Start aufgerufen
  /// (feuern-und-vergessen — blockiert nicht).
  Future<void> verbinde() async {
    _verbindungGestartet = true;
    final user = AuthService().benutzer;
    _status = CloudStatus.verbinde;
    notifyListeners();
    if (user.isEmpty) {
      _status = CloudStatus.fehler;
      notifyListeners();
      return;
    }
    final ok = await login(user);
    if (!ok) {
      _status = CloudStatus.fehler;
      notifyListeners();
      return;
    }
    final st = await statusDaten();
    _status = st != null ? CloudStatus.verbunden : CloudStatus.fehler;
    notifyListeners();
  }

  /// Login mit Baka-Auth – Token wird aus AuthService bezogen
  Future<bool> login(String user) async {
    try {
      final r = await _client
          .get(Uri.parse('$_base/api/v1/cloud/status'),
              headers: _authHeader)
          .timeout(const Duration(seconds: 5));
      return r.statusCode == 200;
    } catch (_) {
      return false;
    }
  }

  Map<String, String> get _authHeader {
    final token = AuthService().token;
    final headers = <String, String>{};
    if (token != null && token.isNotEmpty) {
      headers['Authorization'] = 'Bearer $token';
    }
    return headers;
  }

  Map<String, String> get _jsonHeader => {
        ..._authHeader,
        'Content-Type': 'application/json',
      };

  /// Server-Status abrufen (Song-Zähler etc.)
  Future<Map?> statusDaten() => _get('/api/v1/cloud/status');

  Future<Map?> syncStatus() => _get('/api/v1/cloud/sync-status');

  Future<Map?> syncAll() => _post('/api/v1/cloud/sync-all', {});

  Future<List<Map>> listSongs() async {
    final r = await _get('/api/v1/cloud/list');
    return List<Map>.from(r?['songs'] ?? []);
  }

  Future<String?> upload(String filepath, String filename) async {
    try {
      final req =
          http.MultipartRequest('POST', Uri.parse('$_base/api/v1/cloud/upload'));
      req.headers.addAll(_authHeader);
      req.files.add(
          await http.MultipartFile.fromPath('file', filepath,
              filename: filename));
      final resp = await _client.send(req).timeout(const Duration(seconds: 120));
      final body = jsonDecode(await resp.stream.bytesToString());
      return body['song_id'] as String?;
    } catch (e) {
      MeloLogger().fehler('cloud_upload', e);
      return null;
    }
  }

  Future<bool> download(String songId, String destPath) async {
    try {
      final r = await _client
          .get(Uri.parse('$_base/api/v1/cloud/download/$songId'),
              headers: _authHeader)
          .timeout(const Duration(seconds: 120));
      if (r.statusCode == 200) {
        await File(destPath).writeAsBytes(r.bodyBytes);
        return true;
      }
      return false;
    } catch (e) {
      MeloLogger().fehler('cloud_download', e);
      return false;
    }
  }

  Future<bool> delete(String songId) async {
    try {
      final r = await _client
          .post(Uri.parse('$_base/api/v1/cloud/delete'),
              headers: _jsonHeader,
              body: jsonEncode({'song_id': songId}))
          .timeout(const Duration(seconds: 10));
      return r.statusCode == 200;
    } catch (_) {
      return false;
    }
  }

  /// Sync-Änderungen seit einem Zeitstempel abrufen
  Future<List<Map>> syncChanges(String since) async {
    try {
      final r = await _client
          .post(Uri.parse('$_base/api/v1/cloud/sync'),
              headers: _jsonHeader,
              body: jsonEncode({'since': since}))
          .timeout(const Duration(seconds: 10));
      if (r.statusCode == 200) {
        final d = jsonDecode(r.body);
        return List<Map>.from(d['changes'] ?? []);
      }
    } catch (_) {}
    return [];
  }

  // ─── 📋 Playlisten ───

  /// Alle Playlisten des Users auf dem Server
  Future<List<Map>> getPlaylists() async {
    final r = await _get('/api/v1/cloud/playlists');
    return List<Map>.from(r?['playlists'] ?? []);
  }

  /// Playlist erstellen
  Future<Map?> createPlaylist(String name) async {
    final r = await _post('/api/v1/cloud/playlists', {'name': name});
    return r?['playlist'];
  }

  /// Playlist löschen
  Future<bool> deletePlaylist(int id) async {
    final r = await _post('/api/v1/cloud/playlists', {'id': id});
    return r?['status'] == 'ok';
  }

  /// Playlist-Details mit Songs abrufen
  Future<Map?> getPlaylist(int id) async {
    return await _get('/api/v1/cloud/playlists/$id');
  }

  /// Songs zu Playlist hinzufügen
  Future<int> addSongsToPlaylist(int playlistId, List<String> songIds) async {
    final r = await _post(
        '/api/v1/cloud/playlists/$playlistId/songs', {'song_ids': songIds});
    return r?['added'] ?? 0;
  }

  /// Song aus Playlist entfernen
  Future<bool> removeSongFromPlaylist(int playlistId, String songId) async {
    try {
      final r = await _client
          .delete(
              Uri.parse(
                  '$_base/api/v1/cloud/playlists/$playlistId/songs/$songId'),
              headers: _authHeader)
          .timeout(const Duration(seconds: 10));
      return r.statusCode == 200;
    } catch (_) {
      return false;
    }
  }

  /// Playlist-Positionen aktualisieren
  Future<bool> updatePlaylistPositions(
      int playlistId, List<Map<String, dynamic>> positions) async {
    try {
      final r = await _client
          .put(
              Uri.parse(
                  '$_base/api/v1/cloud/playlists/$playlistId/positions'),
              headers: _jsonHeader,
              body: jsonEncode({'positions': positions}))
          .timeout(const Duration(seconds: 10));
      return r.statusCode == 200;
    } catch (_) {
      return false;
    }
  }

  // ─── ⭐ Favoriten ───

  /// Favoriten vom Server abrufen
  Future<List<Map>> getFavorites() async {
    final r = await _get('/api/v1/cloud/favorites');
    return List<Map>.from(r?['favorites'] ?? []);
  }

  /// Favoriten synchronisieren (komplette Liste senden)
  Future<bool> syncFavorites(List<String> songIds) async {
    final r =
        await _post('/api/v1/cloud/favorites', {'song_ids': songIds});
    return r?['status'] == 'ok';
  }

  /// Einzelnen Favoriten toggeln
  Future<Map?> toggleFavorite(String songId) async {
    return await _post('/api/v1/cloud/favorites/toggle', {'song_id': songId});
  }

  /// Favoriten-Status deterministisch setzen (KEIN Toggle): der Server
  /// erzwingt den gewünschten Zustand (`set`-Parameter). Verhindert
  /// Doppel-Toggle, wenn der Server-Zustand vom lokalen abweicht
  /// (Feuer-und-Vergessen-Push beim lokalen Favoriten-Toggle).
  Future<bool> setFavorite(String songId, {required bool favorit}) async {
    final r = await _post('/api/v1/cloud/favorites/toggle', {
      'song_id': songId,
      'set': favorit,
    });
    return r?['status'] == 'ok';
  }

  // ─── ✏️ Umbenennen ───

  /// Song umbenennen (benutzerdefinierter Titel/Artist)
  Future<Map?> renameSong(String songId,
      {String? title, String? artist}) async {
    final body = <String, dynamic>{'song_id': songId};
    if (title != null) body['title'] = title;
    if (artist != null) body['artist'] = artist;
    return await _post('/api/v1/cloud/rename', body);
  }

  // ─── 🕐 Verlauf ───

  /// Wiedergabe-Verlauf vom Server abrufen
  Future<List<Map>> getHistory({int limit = 50}) async {
    final r = await _get('/api/v1/cloud/history?limit=$limit');
    return List<Map>.from(r?['history'] ?? []);
  }

  /// Wiedergabe-Verlauf-Einträge hochladen
  Future<int> addHistory(List<Map<String, dynamic>> entries) async {
    final r = await _post('/api/v1/cloud/history', {'entries': entries});
    return r?['added'] ?? 0;
  }

  // ─── 🌐 Global / Shared ───

  Future<List<Map>> globalList() async {
    try {
      final r = await _client
          .get(Uri.parse('$_base/api/v1/cloud/global'), headers: _authHeader)
          .timeout(const Duration(seconds: 10));
      if (r.statusCode == 200) {
        return List<Map>.from(jsonDecode(r.body)['songs'] ?? []);
      }
    } catch (_) {}
    return [];
  }

  Future<bool> toggleGlobal(String songId) async {
    try {
      final r = await _client
          .post(Uri.parse('$_base/api/v1/cloud/toggle-global'),
              headers: _jsonHeader,
              body: jsonEncode({'song_id': songId}))
          .timeout(const Duration(seconds: 10));
      return r.statusCode == 200;
    } catch (_) {
      return false;
    }
  }

  Future<String?> share(List<String> songIds) async {
    try {
      final r = await _client
          .post(Uri.parse('$_base/api/v1/cloud/share'),
              headers: _jsonHeader,
              body: jsonEncode({'song_ids': songIds}))
          .timeout(const Duration(seconds: 10));
      if (r.statusCode == 200) {
        final d = jsonDecode(r.body);
        return d['code'] as String?;
      }
    } catch (_) {}
    return null;
  }

  Future<Map?> importCode(String code) async {
    try {
      final r = await _client
          .post(Uri.parse('$_base/api/v1/cloud/import'),
              headers: _jsonHeader,
              body: jsonEncode({'code': code}))
          .timeout(const Duration(seconds: 10));
      if (r.statusCode == 200) return jsonDecode(r.body);
    } catch (_) {}
    return null;
  }

  Future<List<Map>> getCorrupted() async {
    try {
      final r = await _client
          .get(Uri.parse('$_base/api/v1/cloud/corrupted'), headers: _authHeader)
          .timeout(const Duration(seconds: 15));
      if (r.statusCode == 200) {
        final d = jsonDecode(r.body);
        return List<Map>.from(d['corrupted'] ?? []);
      }
    } catch (e) {
      MeloLogger().fehler('cloud_corrupted', e);
    }
    return [];
  }

  // ─── Hilfsmethoden ───

  Future<Map?> _get(String path) async {
    try {
      final r = await _client
          .get(Uri.parse('$_base$path'), headers: _authHeader)
          .timeout(const Duration(seconds: 10));
      if (r.statusCode == 200) return jsonDecode(r.body);
      MeloLogger().fehler('cloud_get', '${r.statusCode} $path');
    } catch (e) {
      MeloLogger().fehler('cloud_get_error', '$path: $e');
    }
    return null;
  }

  Future<Map?> _post(String path, Map<String, dynamic> body) async {
    try {
      final r = await _client
          .post(Uri.parse('$_base$path'),
              headers: _jsonHeader, body: jsonEncode(body))
          .timeout(const Duration(seconds: 10));
      if (r.statusCode == 200) return jsonDecode(r.body);
      MeloLogger().fehler('cloud_post', '${r.statusCode} $path');
    } catch (e) {
      MeloLogger().fehler('cloud_post_error', '$path: $e');
    }
    return null;
  }
}