import 'dart:io';

import 'package:file_picker/file_picker.dart';
import 'package:flutter/foundation.dart';
import 'package:uuid/uuid.dart';

import 'android_scan.dart';
import 'database.dart';
import 'permissions.dart';
import 'scan_service.dart';

/// Beschriftung des Hinzufügen-/Scan-Buttons je Plattform.
String get addMusicLabel =>
    Platform.isAndroid ? 'Musik scannen' : 'Musikordner hinzufügen';

/// Koordiniert Ordnerwahl und Scans; hält den Scan-Fortschritt für die UI.
/// Android scannt automatisch über MediaStore (Scoped Storage lässt keinen
/// direkten Dateizugriff zu); Desktop scannt vom Nutzer gewählte Ordner.
class LibraryService extends ChangeNotifier {
  LibraryService(this.db);
  final MeloDb db;
  static const _uuid = Uuid();

  bool scanning = false;
  int scanDone = 0;
  int scanTotal = 0;
  bool permissionDenied = false;
  String? scanError;

  /// Auf Android: automatischer Geräte-Scan. Auf Desktop: Ordner wählen + scannen.
  Future<void> pickFolderAndScan() async {
    if (!await _ensurePermission()) return;
    if (Platform.isAndroid) {
      await _scan();
      return;
    }
    final path = await FilePicker.getDirectoryPath();
    if (path == null) return;
    await db.addFolder(FoldersCompanion.insert(
      id: _uuid.v4(),
      path: path,
      updatedAtMs: DateTime.now().millisecondsSinceEpoch,
    ));
    await _scan();
  }

  /// Scannt erneut (Android: ganzes Gerät; Desktop: alle gemerkten Ordner).
  Future<void> rescan() async {
    if (!await _ensurePermission()) return;
    await _scan();
  }

  Future<bool> _ensurePermission() async {
    final granted = await ensureAudioPermission();
    permissionDenied = !granted;
    notifyListeners();
    return granted;
  }

  Future<void> _scan() async {
    if (scanning) return;
    scanning = true;
    scanDone = 0;
    scanTotal = 0;
    scanError = null;
    notifyListeners();
    try {
      if (Platform.isAndroid) {
        await scanAndroidMediaStore(db, onProgress: _onProgress);
      } else {
        final folders = (await db.activeFolders()).map((f) => f.path).toList();
        await scanFolders(db, folders, onProgress: _onProgress);
      }
    } catch (e) {
      scanError = 'Scan fehlgeschlagen: $e';
    } finally {
      scanning = false;
      notifyListeners();
    }
  }

  void _onProgress(int done, int total) {
    scanDone = done;
    scanTotal = total;
    notifyListeners();
  }
}