import 'dart:convert';
import 'dart:io';

import '../interfaces/resume_storage.dart';

// 注意：这个实现需要 path_provider 包
// 在实际使用时需要在 pubspec.yaml 中添加 path_provider: ^2.1.0

/// 基于本地文件的断点续传存储实现
class LocalResumeStorage implements ResumeStorage {
  static const String _storageDir = 'yx_oss_resume';
  static const String _fileExtension = '.json';

  Directory? _cacheDirectory;

  /// 获取缓存目录
  Future<Directory> get cacheDirectory async {
    if (_cacheDirectory != null) {
      return _cacheDirectory!;
    }

    // 简化实现：使用临时目录，避免依赖 path_provider
    // 在实际集成时可以替换为 getApplicationDocumentsDirectory()
    final tempDir = Directory.systemTemp;
    _cacheDirectory = Directory('${tempDir.path}/$_storageDir');

    // 确保目录存在
    if (!await _cacheDirectory!.exists()) {
      await _cacheDirectory!.create(recursive: true);
    }

    return _cacheDirectory!;
  }

  /// 获取任务文件路径
  Future<File> _getTaskFile(String taskId) async {
    final dir = await cacheDirectory;
    return File('${dir.path}/$taskId$_fileExtension');
  }

  @override
  Future<void> saveResumeInfo(
      String taskId, Map<String, dynamic> resumeInfo) async {
    try {
      final file = await _getTaskFile(taskId);
      final jsonString = jsonEncode(resumeInfo);
      await file.writeAsString(jsonString);
    } catch (e) {
      throw Exception('Failed to save resume info for task $taskId: $e');
    }
  }

  @override
  Future<Map<String, dynamic>?> loadResumeInfo(String taskId) async {
    try {
      final file = await _getTaskFile(taskId);

      if (!await file.exists()) {
        return null;
      }

      final jsonString = await file.readAsString();
      return jsonDecode(jsonString) as Map<String, dynamic>;
    } catch (e) {
      // 文件损坏或格式错误时删除文件
      try {
        final file = await _getTaskFile(taskId);
        if (await file.exists()) {
          await file.delete();
        }
      } catch (_) {
        // 忽略删除错误
      }
      return null;
    }
  }

  @override
  Future<void> deleteResumeInfo(String taskId) async {
    try {
      final file = await _getTaskFile(taskId);
      if (await file.exists()) {
        await file.delete();
      }
    } catch (e) {
      // 忽略删除错误，可能文件已不存在
    }
  }

  @override
  Future<List<String>> getAllTaskIds() async {
    try {
      final dir = await cacheDirectory;
      if (!await dir.exists()) {
        return [];
      }

      final files = await dir.list().toList();
      final taskIds = <String>[];

      for (final file in files) {
        if (file is File && file.path.endsWith(_fileExtension)) {
          final fileName = file.path.split('/').last;
          final taskId =
              fileName.substring(0, fileName.length - _fileExtension.length);
          taskIds.add(taskId);
        }
      }

      return taskIds;
    } catch (e) {
      return [];
    }
  }

  @override
  Future<void> clearAll() async {
    try {
      final dir = await cacheDirectory;
      if (await dir.exists()) {
        await dir.delete(recursive: true);
      }
      _cacheDirectory = null; // 重置缓存目录
    } catch (e) {
      // 忽略删除错误
    }
  }

  @override
  Future<int> getStorageSize() async {
    try {
      final dir = await cacheDirectory;
      if (!await dir.exists()) {
        return 0;
      }

      int totalSize = 0;
      final files = await dir.list().toList();

      for (final file in files) {
        if (file is File) {
          final stat = await file.stat();
          totalSize += stat.size;
        }
      }

      return totalSize;
    } catch (e) {
      return 0;
    }
  }

  /// 清理过期的断点续传信息
  ///
  /// [maxAge] 最大保留时间（天数）
  Future<void> cleanupExpiredTasks(int maxAge) async {
    try {
      final dir = await cacheDirectory;
      if (!await dir.exists()) {
        return;
      }

      final cutoffTime = DateTime.now().subtract(Duration(days: maxAge));
      final files = await dir.list().toList();

      for (final file in files) {
        if (file is File && file.path.endsWith(_fileExtension)) {
          final stat = await file.stat();
          if (stat.modified.isBefore(cutoffTime)) {
            try {
              await file.delete();
            } catch (_) {
              // 忽略删除错误
            }
          }
        }
      }
    } catch (e) {
      // 忽略清理错误
    }
  }

  /// 获取任务的文件大小
  Future<int> getTaskFileSize(String taskId) async {
    try {
      final file = await _getTaskFile(taskId);
      if (await file.exists()) {
        final stat = await file.stat();
        return stat.size;
      }
      return 0;
    } catch (e) {
      return 0;
    }
  }
}