import 'dart:io';
import 'package:path/path.dart' as path;
import 'package:path_provider/path_provider.dart' as path_provider;
import '../errors/app_error.dart';
import 'logger.dart';

/// 文件工具类
/// 提供文件存储、路径管理、存储空间检查等功能
class FileUtils {
  // 私有构造函数，防止实例化
  FileUtils._();

  /// 获取应用文档目录
  static Future<Directory> getApplicationDocumentsDirectory() async {
    try {
      final directory = await path_provider.getApplicationDocumentsDirectory();
      Logger.debug('获取应用文档目录: ${directory.path}');
      return directory;
    } catch (error, stackTrace) {
      Logger.error('获取应用文档目录失败', error: error, stackTrace: stackTrace);
      throw StorageError(
        message: '获取应用文档目录失败: ${error.toString()}',
        code: 'STORAGE_ERROR',
        stackTrace: stackTrace,
      );
    }
  }

  /// 获取临时目录
  static Future<Directory> getTemporaryDirectory() async {
    try {
      final directory = await path_provider.getTemporaryDirectory();
      Logger.debug('获取临时目录: ${directory.path}');
      return directory;
    } catch (error, stackTrace) {
      Logger.error('获取临时目录失败', error: error, stackTrace: stackTrace);
      throw StorageError(
        message: '获取临时目录失败: ${error.toString()}',
        code: 'STORAGE_ERROR',
        stackTrace: stackTrace,
      );
    }
  }

  /// 获取应用支持目录（用于存储应用数据）
  static Future<Directory> getApplicationSupportDirectory() async {
    try {
      final directory = await path_provider.getApplicationSupportDirectory();
      Logger.debug('获取应用支持目录: ${directory.path}');
      return directory;
    } catch (error, stackTrace) {
      Logger.error('获取应用支持目录失败', error: error, stackTrace: stackTrace);
      throw StorageError(
        message: '获取应用支持目录失败: ${error.toString()}',
        code: 'STORAGE_ERROR',
        stackTrace: stackTrace,
      );
    }
  }

  /// 创建应用存储目录结构
  /// 按照日期格式创建目录：/yyyy/MM/dd/
  static Future<String> createStorageDirectory(DateTime date) async {
    try {
      final supportDir = await getApplicationSupportDirectory();
      
      // 构建日期路径
      final year = date.year.toString();
      final month = date.month.toString().padLeft(2, '0');
      final day = date.day.toString().padLeft(2, '0');
      
      final storagePath = path.join(supportDir.path, 'images', year, month, day);
      final storageDir = Directory(storagePath);
      
      // 如果目录不存在，创建目录
      if (!await storageDir.exists()) {
        await storageDir.create(recursive: true);
        Logger.debug('创建存储目录: $storagePath');
      }
      
      return storagePath;
    } catch (error, stackTrace) {
      Logger.error('创建存储目录失败', error: error, stackTrace: stackTrace);
      throw StorageError(
        message: '创建存储目录失败: ${error.toString()}',
        code: 'STORAGE_ERROR',
        stackTrace: stackTrace,
      );
    }
  }

  /// 创建缩略图存储目录
  static Future<String> createThumbnailDirectory(DateTime date) async {
    try {
      final supportDir = await getApplicationSupportDirectory();
      
      // 构建日期路径
      final year = date.year.toString();
      final month = date.month.toString().padLeft(2, '0');
      final day = date.day.toString().padLeft(2, '0');
      
      final thumbnailPath = path.join(supportDir.path, 'thumbnails', year, month, day);
      final thumbnailDir = Directory(thumbnailPath);
      
      // 如果目录不存在，创建目录
      if (!await thumbnailDir.exists()) {
        await thumbnailDir.create(recursive: true);
        Logger.debug('创建缩略图目录: $thumbnailPath');
      }
      
      return thumbnailPath;
    } catch (error, stackTrace) {
      Logger.error('创建缩略图目录失败', error: error, stackTrace: stackTrace);
      throw StorageError(
        message: '创建缩略图目录失败: ${error.toString()}',
        code: 'STORAGE_ERROR',
        stackTrace: stackTrace,
      );
    }
  }

  /// 创建临时文件目录
  static Future<String> createTempDirectory() async {
    try {
      final tempDir = await getTemporaryDirectory();
      final inspoSnapTempPath = path.join(tempDir.path, 'insposnap_temp');
      final tempDirectory = Directory(inspoSnapTempPath);
      
      if (!await tempDirectory.exists()) {
        await tempDirectory.create(recursive: true);
        Logger.debug('创建临时目录: $inspoSnapTempPath');
      }
      
      return inspoSnapTempPath;
    } catch (error, stackTrace) {
      Logger.error('创建临时目录失败', error: error, stackTrace: stackTrace);
      throw StorageError(
        message: '创建临时目录失败: ${error.toString()}',
        code: 'STORAGE_ERROR',
        stackTrace: stackTrace,
      );
    }
  }

  /// 检查存储空间是否充足
  static Future<bool> hasEnoughStorageSpace({int requiredBytes = 100 * 1024 * 1024}) async {
    try {
      final directory = await getApplicationSupportDirectory();
      // final stat = await FileStat.stat(directory.path);
      
      // 获取可用空间（这里简化处理，实际需要更复杂的计算）
      // 在实际应用中，可能需要使用 platform-specific 代码来获取准确的可用空间
      
      // 模拟检查：如果目录存在且有写入权限，则认为空间充足
      final testFile = File(path.join(directory.path, '.space_test'));
      try {
        await testFile.writeAsString('test');
        await testFile.delete();
        Logger.debug('存储空间检查通过');
        return true;
      } catch (e) {
        Logger.warning('存储空间可能不足或没有写入权限');
        return false;
      }
    } catch (error, stackTrace) {
      Logger.error('检查存储空间失败', error: error, stackTrace: stackTrace);
      return false;
    }
  }

  /// 获取目录大小（字节）
  static Future<int> getDirectorySize(Directory directory) async {
    try {
      int totalSize = 0;
      
      if (!await directory.exists()) {
        return 0;
      }
      
      await for (final entity in directory.list(recursive: true, followLinks: false)) {
        if (entity is File) {
          try {
            final stat = await entity.stat();
            totalSize += stat.size;
          } catch (e) {
            // 忽略单个文件的错误，继续统计其他文件
            Logger.warning('获取文件大小失败: ${entity.path}');
          }
        }
      }
      
      Logger.debug('目录大小: ${directory.path} = ${(totalSize / 1024 / 1024).toStringAsFixed(2)}MB');
      return totalSize;
    } catch (error, stackTrace) {
      Logger.error('获取目录大小失败', error: error, stackTrace: stackTrace);
      return 0;
    }
  }

  /// 删除目录及其所有内容
  static Future<void> deleteDirectory(Directory directory) async {
    try {
      if (await directory.exists()) {
        await directory.delete(recursive: true);
        Logger.debug('删除目录: ${directory.path}');
      }
    } catch (error, stackTrace) {
      Logger.error('删除目录失败', error: error, stackTrace: stackTrace);
      throw StorageError(
        message: '删除目录失败: ${error.toString()}',
        code: 'STORAGE_ERROR',
        stackTrace: stackTrace,
      );
    }
  }

  /// 清空目录内容（保留目录本身）
  static Future<void> clearDirectory(Directory directory) async {
    try {
      if (!await directory.exists()) {
        return;
      }
      
      await for (final entity in directory.list(followLinks: false)) {
        try {
          if (entity is File) {
            await entity.delete();
          } else if (entity is Directory) {
            await entity.delete(recursive: true);
          }
        } catch (e) {
          // 忽略单个文件/目录的删除错误
          Logger.warning('删除失败: ${entity.path}');
        }
      }
      
      Logger.debug('清空目录: ${directory.path}');
    } catch (error, stackTrace) {
      Logger.error('清空目录失败', error: error, stackTrace: stackTrace);
      throw StorageError(
        message: '清空目录失败: ${error.toString()}',
        code: 'STORAGE_ERROR',
        stackTrace: stackTrace,
      );
    }
  }

  /// 复制文件
  static Future<File> copyFile(String sourcePath, String targetPath) async {
    try {
      final sourceFile = File(sourcePath);
      if (!await sourceFile.exists()) {
        throw StorageError(
          message: '源文件不存在: $sourcePath',
          code: 'STORAGE_ERROR',
        );
      }
      
      // 确保目标目录存在
      final targetDir = Directory(path.dirname(targetPath));
      if (!await targetDir.exists()) {
        await targetDir.create(recursive: true);
      }
      
      final targetFile = await sourceFile.copy(targetPath);
      Logger.debug('复制文件: $sourcePath -> $targetPath');
      return targetFile;
    } catch (error, stackTrace) {
      Logger.error('复制文件失败', error: error, stackTrace: stackTrace);
      throw StorageError(
        message: '复制文件失败: ${error.toString()}',
        code: 'STORAGE_ERROR',
        stackTrace: stackTrace,
      );
    }
  }

  /// 移动文件
  static Future<File> moveFile(String sourcePath, String targetPath) async {
    try {
      final sourceFile = File(sourcePath);
      if (!await sourceFile.exists()) {
        throw StorageError(
          message: '源文件不存在: $sourcePath',
          code: 'STORAGE_ERROR',
        );
      }
      
      // 确保目标目录存在
      final targetDir = Directory(path.dirname(targetPath));
      if (!await targetDir.exists()) {
        await targetDir.create(recursive: true);
      }
      
      final targetFile = await sourceFile.rename(targetPath);
      Logger.debug('移动文件: $sourcePath -> $targetPath');
      return targetFile;
    } catch (error, stackTrace) {
      Logger.error('移动文件失败', error: error, stackTrace: stackTrace);
      throw StorageError(
        message: '移动文件失败: ${error.toString()}',
        code: 'STORAGE_ERROR',
        stackTrace: stackTrace,
      );
    }
  }

  /// 获取文件扩展名
  static String getFileExtension(String filePath) {
    return path.extension(filePath).toLowerCase();
  }

  /// 获取文件名（不含路径）
  static String getFileName(String filePath) {
    return path.basename(filePath);
  }

  /// 获取文件名（不含扩展名）
  static String getFileNameWithoutExtension(String filePath) {
    return path.basenameWithoutExtension(filePath);
  }

  /// 生成唯一的文件名
  static String generateUniqueFileName(String originalFileName) {
    final timestamp = DateTime.now().millisecondsSinceEpoch;
    final extension = getFileExtension(originalFileName);
    final nameWithoutExt = getFileNameWithoutExtension(originalFileName);
    return '${nameWithoutExt}_$timestamp$extension';
  }

  /// 检查文件是否存在
  static Future<bool> fileExists(String filePath) async {
    try {
      final file = File(filePath);
      return await file.exists();
    } catch (error) {
      Logger.error('检查文件存在失败', error: error);
      return false;
    }
  }

  /// 获取文件大小（字节）
  static Future<int> getFileSize(String filePath) async {
    try {
      final file = File(filePath);
      if (await file.exists()) {
        final stat = await file.stat();
        return stat.size;
      }
      return 0;
    } catch (error) {
      Logger.error('获取文件大小失败', error: error);
      return 0;
    }
  }

  /// 格式化文件大小
  static String formatFileSize(int bytes) {
    if (bytes <= 0) return '0 B';
    
    const units = ['B', 'KB', 'MB', 'GB', 'TB'];
    int unitIndex = 0;
    double size = bytes.toDouble();
    
    while (size >= 1024 && unitIndex < units.length - 1) {
      size /= 1024;
      unitIndex++;
    }
    
    return '${size.toStringAsFixed(2)} ${units[unitIndex]}';
  }

  /// 清理临时文件
  static Future<void> cleanTempFiles() async {
    try {
      final tempDir = Directory(await createTempDirectory());
      await clearDirectory(tempDir);
      Logger.info('临时文件清理完成');
    } catch (error, stackTrace) {
      Logger.error('清理临时文件失败', error: error, stackTrace: stackTrace);
    }
  }

  /// 获取存储使用情况
  static Future<Map<String, dynamic>> getStorageUsage() async {
    try {
      final supportDir = await getApplicationSupportDirectory();
      final imagesDir = Directory(path.join(supportDir.path, 'images'));
      final thumbnailsDir = Directory(path.join(supportDir.path, 'thumbnails'));
      
      final imagesSize = await getDirectorySize(imagesDir);
      final thumbnailsSize = await getDirectorySize(thumbnailsDir);
      final totalSize = imagesSize + thumbnailsSize;
      
      return {
        'imagesSize': imagesSize,
        'thumbnailsSize': thumbnailsSize,
        'totalSize': totalSize,
        'imagesSizeFormatted': formatFileSize(imagesSize),
        'thumbnailsSizeFormatted': formatFileSize(thumbnailsSize),
        'totalSizeFormatted': formatFileSize(totalSize),
      };
    } catch (error, stackTrace) {
      Logger.error('获取存储使用情况失败', error: error, stackTrace: stackTrace);
      return {
        'imagesSize': 0,
        'thumbnailsSize': 0,
        'totalSize': 0,
        'imagesSizeFormatted': '0 B',
        'thumbnailsSizeFormatted': '0 B',
        'totalSizeFormatted': '0 B',
      };
    }
  }
}

/// 文件信息类
class FileInfo {
  final String path;
  final String name;
  final String extension;
  final int size;
  final DateTime modifiedTime;
  final bool exists;

  FileInfo({
    required this.path,
    required this.name,
    required this.extension,
    required this.size,
    required this.modifiedTime,
    required this.exists,
  });

  factory FileInfo.fromFile(File file, [String? filePath]) {
    final path = filePath ?? file.path;
    final stat = file.statSync();
    
    return FileInfo(
      path: path,
      name: file.uri.pathSegments.last,
      extension: FileUtils.getFileExtension(path),
      size: stat.size,
      modifiedTime: stat.modified,
      exists: stat.type != FileSystemEntityType.notFound,
    );
  }

  String get sizeFormatted => FileUtils.formatFileSize(size);

  @override
  String toString() {
    return 'FileInfo{path: $path, name: $name, size: $sizeFormatted, modified: $modifiedTime}';
  }
}