更新下载进度，修复不能重新下载的问题

backend/services/file-manager.js

@@ -0,0 +1,239 @@
+const axios = require('axios');
+const fs = require('fs-extra');
+const path = require('path');
+const crypto = require('crypto');
+const ConfigManager = require('../config/config-manager');
+
+/**
+ * 文件管理器 - 负责文件下载、检查和目录管理
+ */
+class FileManager {
+  constructor() {
+    this.configManager = new ConfigManager();
+    
+    // 下载配置
+    this.downloadConfig = {
+      timeout: 300000, // 5分钟超时
+      chunkSize: 1024 * 1024, // 1MB块大小
+      retryAttempts: 3, // 重试次数
+      retryDelay: 2000, // 重试延迟
+      concurrentDownloads: 3 // 并发下载数
+    };
+  }
+
+  /**
+   * 获取当前下载路径
+   */
+  async getDownloadPath() {
+    try {
+      const config = await this.configManager.readConfig();
+      const downloadDir = config.downloadDir || './downloads';
+      
+      // 如果是相对路径，转换为绝对路径
+      return path.isAbsolute(downloadDir) 
+        ? downloadDir 
+        : path.resolve(process.cwd(), downloadDir);
+    } catch (error) {
+      console.error('获取下载路径失败:', error);
+      // 返回默认路径
+      return path.resolve(process.cwd(), 'downloads');
+    }
+  }
+
+  /**
+   * 计算文件MD5
+   */
+  async calculateFileMD5(filePath) {
+    return new Promise((resolve, reject) => {
+      const hash = crypto.createHash('md5');
+      const stream = fs.createReadStream(filePath);
+      
+      stream.on('data', (data) => {
+        hash.update(data);
+      });
+      
+      stream.on('end', () => {
+        resolve(hash.digest('hex'));
+      });
+      
+      stream.on('error', reject);
+    });
+  }
+
+  /**
+   * 检查文件完整性
+   */
+  async checkFileIntegrity(filePath, expectedSize = null) {
+    try {
+      if (!await fs.pathExists(filePath)) {
+        return { valid: false, reason: '文件不存在' };
+      }
+
+      const stats = await fs.stat(filePath);
+      
+      // 检查文件大小
+      if (expectedSize && stats.size !== expectedSize) {
+        return { valid: false, reason: '文件大小不匹配', actual: stats.size, expected: expectedSize };
+      }
+      
+      // 检查文件是否为空
+      if (stats.size === 0) {
+        return { valid: false, reason: '文件为空' };
+      }
+
+      return { valid: true, size: stats.size };
+    } catch (error) {
+      return { valid: false, reason: '检查文件失败', error: error.message };
+    }
+  }
+
+  /**
+   * 简单的文件下载方法
+   */
+  async downloadFile(url, filePath) {
+    const response = await axios({
+      method: 'GET',
+      url: url,
+      responseType: 'stream',
+      headers: {
+        'Referer': 'https://www.pixiv.net/',
+        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36'
+      },
+      timeout: 60000
+    });
+
+    const writer = fs.createWriteStream(filePath);
+    response.data.pipe(writer);
+
+    return new Promise((resolve, reject) => {
+      writer.on('finish', resolve);
+      writer.on('error', (error) => {
+        // 下载失败时删除文件
+        fs.unlink(filePath, () => {});
+        reject(error);
+      });
+    });
+  }
+
+  /**
+   * 获取文件扩展名
+   */
+  getFileExtension(url) {
+    const match = url.match(/\.([a-zA-Z0-9]+)(\?|$)/);
+    return match ? `.${match[1]}` : '.jpg';
+  }
+
+  /**
+   * 获取目录大小
+   */
+  async getDirectorySize(dirPath) {
+    try {
+      const files = await fs.readdir(dirPath);
+      let totalSize = 0;
+      
+      for (const file of files) {
+        const filePath = path.join(dirPath, file);
+        const stat = await fs.stat(filePath);
+        if (stat.isFile()) {
+          totalSize += stat.size;
+        }
+      }
+      
+      return totalSize;
+    } catch (error) {
+      return 0;
+    }
+  }
+
+  /**
+   * 创建安全的目录名
+   */
+  createSafeDirectoryName(name) {
+    return name.replace(/[<>:"/\\|?*]/g, '_');
+  }
+
+  /**
+   * 确保目录存在
+   */
+  async ensureDirectory(dirPath) {
+    await fs.ensureDir(dirPath);
+  }
+
+  /**
+   * 删除目录
+   */
+  async removeDirectory(dirPath) {
+    if (await fs.pathExists(dirPath)) {
+      await fs.remove(dirPath);
+    }
+  }
+
+  /**
+   * 检查目录是否存在
+   */
+  async directoryExists(dirPath) {
+    return await fs.pathExists(dirPath);
+  }
+
+  /**
+   * 列出目录内容
+   */
+  async listDirectory(dirPath) {
+    try {
+      return await fs.readdir(dirPath);
+    } catch (error) {
+      return [];
+    }
+  }
+
+  /**
+   * 复制文件
+   */
+  async copyFile(src, dest) {
+    await fs.copy(src, dest);
+  }
+
+  /**
+   * 移动文件
+   */
+  async moveFile(src, dest) {
+    await fs.move(src, dest);
+  }
+
+  /**
+   * 删除文件
+   */
+  async deleteFile(filePath) {
+    if (await fs.pathExists(filePath)) {
+      await fs.unlink(filePath);
+    }
+  }
+
+  /**
+   * 检查文件是否存在
+   */
+  async fileExists(filePath) {
+    return await fs.pathExists(filePath);
+  }
+
+  /**
+   * 获取文件信息
+   */
+  async getFileInfo(filePath) {
+    try {
+      const stats = await fs.stat(filePath);
+      return {
+        exists: true,
+        size: stats.size,
+        created: stats.birthtime,
+        modified: stats.mtime,
+        isFile: stats.isFile(),
+        isDirectory: stats.isDirectory()
+      };
+    } catch (error) {
+      return { exists: false };
+    }
+  }
+}
+
+module.exports = FileManager;