// lib/metadata/file_provider.dart
import 'dart:io';
import 'package:flutter/foundation.dart'; // ⭐ 添加
import 'package:path_provider/path_provider.dart';
import 'package:dio/dio.dart';
import '../services/webdav_service.dart';

abstract class FileProvider {
  Future<File?> getFile(String url);
}

class WebDAVFileProvider implements FileProvider {
  final Dio _dio = Dio();

  @override
  Future<File?> getFile(String url) async {
    try {
      // 1. 获取缓存目录
      final cacheDir = await getTemporaryDirectory();
      final cachePath = '${cacheDir.path}/metadata_${url.hashCode}.tmp';
      final cacheFile = File(cachePath);

      // 2. 如果缓存存在且未过期，直接返回
      if (await cacheFile.exists()) {
        final stat = await cacheFile.stat();
        // 缓存 1 小时内有效（86400 秒）
        if (DateTime.now().difference(stat.modified).inSeconds < 86400) {
          return cacheFile;
        }
      }

      // 3. 获取认证头
      final headers = await WebDAVService.instance.getAuthHeaders();
      if (headers.isEmpty) return null;

      // 4. 只下载前 1MB
      await _dio.download(
        url,
        cachePath,
        options: Options(
          headers: headers,
          receiveTimeout: const Duration(seconds: 10),
          sendTimeout: const Duration(seconds: 10),
        ),
      );

      return cacheFile;
    } catch (e) {
      debugPrint('⚠️ [WebDAVFileProvider] download failed: $e');
      return null;
    }
  }
}

class LocalFileProvider implements FileProvider {
  @override
  Future<File?> getFile(String url) async {
    final file = File(url);
    if (await file.exists()) {
      return file;
    }
    return null;
  }
}