import 'dart:io';
import 'package:dio/dio.dart';
import 'package:dio/io.dart';
import 'package:path_provider/path_provider.dart';
import 'package:path/path.dart';
import 'package:logger/web.dart';

/// OTA下载服务
/// 负责处理固件包的下载、文件管理等功能
class OtaDownloadService {
  late final Dio _dio;

  /// 构造函数
  /// 初始化Dio实例并配置SSL证书处理
  OtaDownloadService() {
    _dio = Dio(BaseOptions(
      connectTimeout: const Duration(seconds: 30), // 增加连接超时时间
      receiveTimeout: Duration.zero,
      sendTimeout: const Duration(seconds: 30), // 增加发送超时时间
      headers: {'Accept-Encoding': 'gzip'},
    ));

    // 配置SSL证书验证
    (_dio.httpClientAdapter as IOHttpClientAdapter).createHttpClient = () {
      final client = HttpClient();

      // 处理SSL证书验证
      client.badCertificateCallback =
          (X509Certificate cert, String host, int port) {
        // 在生产环境中，应该进行适当的证书验证
        // 这里为了解决证书过期问题，暂时跳过验证
        // 建议：在生产环境中实现更安全的证书验证逻辑
        Logger().w('SSL证书验证跳过: $host:$port');
        return true;
      };

      return client;
    };
  }

  /// 下载固件包
  /// [downloadUrl] 下载地址
  /// [onProgress] 下载进度回调
  /// [onStatusUpdate] 状态更新回调
  /// 返回下载文件的本地路径
  /// 抛出异常如果下载失败
  Future<String> downloadFirmware({
    required String downloadUrl,
    required Function(double) onProgress,
    required Function(String) onStatusUpdate,
  }) async {
    onStatusUpdate('准备下载固件包...');

    final fileName = downloadUrl.substring(downloadUrl.lastIndexOf('/') + 1);
    const directoryName = "ota_upgrades";

    // 获取下载目录
    onStatusUpdate('正在获取下载目录...');
    final Directory? downloadsDir = await getApplicationSupportDirectory();
    if (downloadsDir == null) {
      throw FileSystemException('无法访问下载目录');
    }

    final targetDir = Directory('${downloadsDir.path}/Download/$directoryName');
    if (!await targetDir.exists()) {
      onStatusUpdate('创建下载目录...');
      await targetDir.create(recursive: true);
    }

    final savePath = '${targetDir.path}/$fileName';

    // 检查是否已存在同名文件
    onStatusUpdate('检查本地文件...');
    if (await _checkExistingFile(targetDir, fileName)) {
      onStatusUpdate('文件已存在，准备升级...');
      return savePath;
    }

    // 清理旧文件
    onStatusUpdate('清理旧文件...');
    await _cleanOldFiles(targetDir);

    // 开始下载
    onStatusUpdate('开始下载固件包...');
    Logger().d('文件保存路径: $savePath');

    final options = Options(
      receiveTimeout: Duration.zero,
      followRedirects: true,
      maxRedirects: 5,
    );

    await _dio.download(
      downloadUrl,
      savePath,
      options: options,
      onReceiveProgress: (received, total) {
        if (total != -1) {
          final progress = received / total;
          onProgress(progress);
          onStatusUpdate('正在下载固件包... ${(progress * 100).toStringAsFixed(1)}%');
        }
      },
    );

    // 验证文件是否下载成功
    final file = File(savePath);
    if (!await file.exists()) {
      throw FileSystemException('文件下载失败，请检查写入权限');
    }

    onStatusUpdate('下载完成，准备升级...');
    return savePath;
  }

  /// 检查是否存在同名文件
  /// [targetDir] 目标目录
  /// [fileName] 文件名
  /// 返回true表示文件已存在
  Future<bool> _checkExistingFile(Directory targetDir, String fileName) async {
    try {
      final files = await targetDir.list().toList();
      for (var entity in files) {
        if (await FileSystemEntity.isFile(entity.path)) {
          final name = basename(entity.path);
          if (name == fileName) {
            return true;
          }
        }
      }
      return false;
    } catch (e) {
      Logger().d('检查本地文件失败: $e');
      return false;
    }
  }

  /// 清理旧文件
  /// [targetDir] 目标目录
  /// 抛出异常如果清理失败
  Future<void> _cleanOldFiles(Directory targetDir) async {
    try {
      final files = await targetDir.list().toList();
      for (var entity in files) {
        if (await FileSystemEntity.isFile(entity.path)) {
          await entity.delete();
        }
      }
    } catch (e) {
      throw Exception('删除旧文件失败: $e');
    }
  }
}