backend/src/services/huggingfaceStorageService.js

import { fileURLToPath } from 'url';
import { v4 as uuidv4 } from 'uuid';
import crypto from 'crypto';
import path from 'path';
import fs from 'fs/promises';

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);



/**
 * Huggingface存储服务
 * 管理PPT图片文件的内存存储、链接生成和版本控制
 * 利用Huggingface Space的16G内存进行临时存储
 */
class HuggingfaceStorageService {
  constructor() {
    // 文件系统路径配置
    this.usersDir = path.join(__dirname, '../../data/users');
    
    // 内存存储配置
    this.memoryStorage = new Map(); // 存储图片Buffer数据
    this.linkMap = new Map(); // 图片链接映射
    this.metadataMap = new Map(); // 图片元数据映射
    this.userDataMap = new Map(); // 用户数据映射
    
    // 内存管理配置
    this.maxMemoryUsage = 14 * 1024 * 1024 * 1024; // 14GB 最大内存使用量
    this.currentMemoryUsage = 0;
    this.cleanupThreshold = 0.8; // 80%时开始清理
    
    // 缓存策略配置
    this.maxImageAge = 24 * 60 * 60 * 1000; // 24小时过期
    this.maxImagesPerUser = 100; // 每用户最大图片数
    
    this.initialized = false;
    
    // 定期清理内存
    this.startMemoryCleanup();
  }

  /**
   * 初始化内存存储服务
   */
  async initialize() {
    if (this.initialized) return;

    try {
      // 初始化内存存储
      this.memoryStorage.clear();
      this.linkMap.clear();
      this.metadataMap.clear();
      this.userDataMap.clear();
      this.currentMemoryUsage = 0;
      
      this.initialized = true;
      console.log('✅ HuggingfaceStorageService (Memory Mode) initialized successfully');
      console.log(`💾 Max memory usage: ${(this.maxMemoryUsage / 1024 / 1024 / 1024).toFixed(1)}GB`);
      console.log(`🧹 Cleanup threshold: ${(this.cleanupThreshold * 100)}%`);
      console.log(`⏰ Image expiry: ${this.maxImageAge / 1000 / 60 / 60}h`);
    } catch (error) {
      console.error('❌ Failed to initialize HuggingfaceStorageService:', error);
      throw error;
    }
  }

  /**
   * 启动内存清理定时器
   */
  startMemoryCleanup() {
    // 每5分钟检查一次内存使用情况
    setInterval(() => {
      this.performMemoryCleanup();
    }, 5 * 60 * 1000);
    
    console.log('🧹 Memory cleanup scheduler started (every 5 minutes)');
  }

  /**
   * 执行内存清理
   */
  performMemoryCleanup() {
    const memoryUsageRatio = this.currentMemoryUsage / this.maxMemoryUsage;
    
    if (memoryUsageRatio > this.cleanupThreshold) {
      console.log(`🧹 Memory cleanup triggered (${(memoryUsageRatio * 100).toFixed(1)}% usage)`);
      
      // 清理过期图片
      this.cleanupExpiredImages();
      
      // 如果内存使用仍然过高，清理最旧的图片
      if (this.currentMemoryUsage / this.maxMemoryUsage > this.cleanupThreshold) {
        this.cleanupOldestImages();
      }
    }
  }

  /**
   * 清理过期图片
   */
  cleanupExpiredImages() {
    const now = Date.now();
    let cleanedCount = 0;
    let freedMemory = 0;
    
    for (const [imageId, metadata] of this.metadataMap.entries()) {
      const imageAge = now - new Date(metadata.createdAt).getTime();
      
      if (imageAge > this.maxImageAge) {
        const imageData = this.memoryStorage.get(imageId);
        if (imageData) {
          freedMemory += imageData.length;
          this.memoryStorage.delete(imageId);
          this.metadataMap.delete(imageId);
          this.linkMap.delete(imageId);
          cleanedCount++;
        }
      }
    }
    
    this.currentMemoryUsage -= freedMemory;
    
    if (cleanedCount > 0) {
      console.log(`🧹 Cleaned ${cleanedCount} expired images, freed ${(freedMemory / 1024 / 1024).toFixed(1)}MB`);
    }
  }

  /**
   * 清理最旧的图片
   */
  cleanupOldestImages() {
    const images = Array.from(this.metadataMap.entries())
      .sort((a, b) => new Date(a[1].createdAt) - new Date(b[1].createdAt));
    
    const targetCleanup = Math.floor(images.length * 0.2); // 清理20%最旧的图片
    let cleanedCount = 0;
    let freedMemory = 0;
    
    for (let i = 0; i < targetCleanup && i < images.length; i++) {
      const [imageId, metadata] = images[i];
      const imageData = this.memoryStorage.get(imageId);
      
      if (imageData) {
        freedMemory += imageData.length;
        this.memoryStorage.delete(imageId);
        this.metadataMap.delete(imageId);
        this.linkMap.delete(imageId);
        cleanedCount++;
      }
    }
    
    this.currentMemoryUsage -= freedMemory;
    
    if (cleanedCount > 0) {
      console.log(`🧹 Cleaned ${cleanedCount} oldest images, freed ${(freedMemory / 1024 / 1024).toFixed(1)}MB`);
    }
  }



  /**
   * 生成图片ID
   * @param {string} userId - 用户ID
   * @param {string} pptId - PPT ID
   * @param {number} pageIndex - 页面索引
   * @param {string} version - 版本号
   * @returns {string} 图片ID
   */
  generateImageId(userId, pptId, pageIndex, version = 'latest') {
    const data = `${userId}-${pptId}-${pageIndex}-${version}`;
    return crypto.createHash('sha256').update(data).digest('hex').substring(0, 16);
  }

  /**
   * 生成版本号
   * @returns {string} 版本号
   */
  generateVersion() {
    return Date.now().toString();
  }

  /**
   * 存储图片到内存
   * @param {string} userId - 用户ID
   * @param {string} pptId - PPT ID
   * @param {number} pageIndex - 页面索引
   * @param {Buffer} imageBuffer - 图片数据
   * @param {Object} options - 存储选项
   * @returns {Promise<Object>} 存储结果
   */
  async storeImage(userId, pptId, pageIndex, imageBuffer, options = {}) {
    if (!this.initialized) {
      await this.initialize();
    }

    const {
      format = 'png',
      quality = 0.9,
      updateExisting = true
    } = options;

    try {
      // 检查内存使用情况
      if (this.currentMemoryUsage + imageBuffer.length > this.maxMemoryUsage) {
        console.log('⚠️ Memory limit approaching, performing cleanup...');
        this.performMemoryCleanup();
        
        // 如果清理后仍然超出限制，拒绝存储
        if (this.currentMemoryUsage + imageBuffer.length > this.maxMemoryUsage) {
          throw new Error('Memory limit exceeded, cannot store image');
        }
      }
      
      // 检查用户图片数量限制
      const userImages = Array.from(this.metadataMap.values())
        .filter(meta => meta.userId === userId);
      
      if (userImages.length >= this.maxImagesPerUser) {
        // 删除用户最旧的图片
        const oldestImage = userImages
          .sort((a, b) => new Date(a.createdAt) - new Date(b.createdAt))[0];
        
        if (oldestImage) {
          this.deleteImageFromMemory(oldestImage.imageId);
        }
      }
      
      // 生成版本号
      const version = this.generateVersion();
      
      // 生成图片ID
      const imageId = this.generateImageId(userId, pptId, pageIndex, 'latest');
      const versionedImageId = this.generateImageId(userId, pptId, pageIndex, version);
      
      // 如果已存在相同的图片ID，先删除旧的
      if (this.memoryStorage.has(imageId)) {
        this.deleteImageFromMemory(imageId);
      }
      
      // 存储图片到内存
      this.memoryStorage.set(imageId, imageBuffer);
      this.memoryStorage.set(versionedImageId, imageBuffer);
      
      // 更新内存使用量
      this.currentMemoryUsage += imageBuffer.length * 2; // 存储了两份（latest和versioned）
      
      // 创建元数据
      const metadata = {
        imageId,
        versionedImageId,
        userId,
        pptId,
        pageIndex,
        version,
        format,
        createdAt: new Date().toISOString(),
        updatedAt: new Date().toISOString(),
        size: imageBuffer.length,
        memoryStored: true
      };
      
      // 存储元数据
      this.metadataMap.set(imageId, metadata);
      this.metadataMap.set(versionedImageId, { ...metadata, imageId: versionedImageId });
      
      // 更新链接映射
      this.linkMap.set(imageId, metadata);
      this.linkMap.set(versionedImageId, { ...metadata, imageId: versionedImageId });
      
      // 更新用户数据统计
      if (!this.userDataMap.has(userId)) {
        this.userDataMap.set(userId, { imageCount: 0, totalSize: 0 });
      }
      const userData = this.userDataMap.get(userId);
      userData.imageCount++;
      userData.totalSize += imageBuffer.length;
      
      console.log(`✅ Image stored in memory: ${imageId} (${imageBuffer.length} bytes)`);
      console.log(`💾 Memory usage: ${(this.currentMemoryUsage / 1024 / 1024).toFixed(1)}MB / ${(this.maxMemoryUsage / 1024 / 1024 / 1024).toFixed(1)}GB`);
      
      return {
        success: true,
        imageId,
        versionedImageId,
        version,
        url: `/api/images/${imageId}`,
        versionedUrl: `/api/images/${versionedImageId}`,
        memoryStored: true,
        size: imageBuffer.length,
        memoryUsage: {
          current: this.currentMemoryUsage,
          max: this.maxMemoryUsage,
          percentage: (this.currentMemoryUsage / this.maxMemoryUsage * 100).toFixed(1)
        }
      };
    } catch (error) {
      console.error('❌ Failed to store image in memory:', error);
      throw error;
    }
  }

  /**
   * 从内存中删除图片
   * @param {string} imageId - 图片ID
   */
  deleteImageFromMemory(imageId) {
    const imageData = this.memoryStorage.get(imageId);
    if (imageData) {
      this.currentMemoryUsage -= imageData.length;
      this.memoryStorage.delete(imageId);
      this.metadataMap.delete(imageId);
      this.linkMap.delete(imageId);
      
      console.log(`🗑️ Deleted image from memory: ${imageId} (freed ${imageData.length} bytes)`);
    }
  }

  /**
   * 从内存中获取图片
   * @param {string} imageId - 图片ID
   * @returns {Promise<Object>} 图片数据和元信息
   */
  async getImage(imageId) {
    if (!this.initialized) {
      await this.initialize();
    }

    // 从内存中获取图片数据
    const imageBuffer = this.memoryStorage.get(imageId);
    if (!imageBuffer) {
      throw new Error(`Image not found in memory: ${imageId}`);
    }

    // 获取元数据
    const metadata = this.metadataMap.get(imageId);
    if (!metadata) {
      throw new Error(`Image metadata not found: ${imageId}`);
    }

    try {
      return {
        success: true,
        data: imageBuffer,
        metadata: {
          imageId,
          format: metadata.format,
          size: metadata.size,
          createdAt: metadata.createdAt,
          updatedAt: metadata.updatedAt,
          version: metadata.version,
          memoryStored: true
        }
      };
    } catch (error) {
      console.error(`❌ Failed to get image ${imageId}:`, error);
      throw error;
    }
  }

  /**
   * 从内存中删除图片
   * @param {string} imageId - 图片ID
   * @returns {Promise<boolean>} 删除结果
   */
  async deleteImage(imageId) {
    if (!this.initialized) {
      await this.initialize();
    }

    const metadata = this.metadataMap.get(imageId);
    if (!metadata) {
      return false;
    }

    try {
      // 从内存中删除图片数据
      this.deleteImageFromMemory(imageId);
      
      // 如果有版本化的图片ID，也删除它
      if (metadata.versionedImageId && metadata.versionedImageId !== imageId) {
        this.deleteImageFromMemory(metadata.versionedImageId);
      }
      
      // 更新用户数据统计
      const userData = this.userDataMap.get(metadata.userId);
      if (userData) {
        userData.imageCount = Math.max(0, userData.imageCount - 1);
        userData.totalSize = Math.max(0, userData.totalSize - metadata.size);
      }
      
      console.log(`✅ Image deleted from memory: ${imageId}`);
      return true;
    } catch (error) {
      console.error(`❌ Failed to delete image from memory ${imageId}:`, error);
      return false;
    }
  }

  /**
   * 批量存储PPT所有页面图片
   * @param {string} userId - 用户ID
   * @param {string} pptId - PPT ID
   * @param {Array} imageBuffers - 图片Buffer数组
   * @param {Object} options - 存储选项
   * @returns {Promise<Array>} 存储结果数组
   */
  async storeAllImages(userId, pptId, imageBuffers, options = {}) {
    const results = [];
    
    for (let i = 0; i < imageBuffers.length; i++) {
      try {
        if (imageBuffers[i].success) {
          const result = await this.storeImage(
            userId, 
            pptId, 
            i, 
            imageBuffers[i].data, 
            options
          );
          results.push({
            pageIndex: i,
            success: true,
            ...result
          });
        } else {
          results.push({
            pageIndex: i,
            success: false,
            error: imageBuffers[i].error
          });
        }
      } catch (error) {
        results.push({
          pageIndex: i,
          success: false,
          error: error.message
        });
      }
    }
    
    return results;
  }

  /**
   * 存储PPT数据到Huggingface硬盘
   * @param {string} userId - 用户ID
   * @param {string} pptId - PPT ID
   * @param {Object} pptData - PPT数据
   * @returns {Promise<Object>} 存储结果
   */
  async storePPTData(userId, pptId, pptData) {
    if (!this.initialized) {
      await this.initialize();
    }

    try {
      const userDir = path.join(this.usersDir, userId);
      const pptDir = path.join(userDir, pptId);
      
      // 确保目录存在
      await fs.mkdir(pptDir, { recursive: true });
      
      // 存储PPT数据
      const pptDataFile = path.join(pptDir, 'data.json');
      await fs.writeFile(pptDataFile, JSON.stringify(pptData, null, 2));
      
      // 存储元数据
      const metadata = {
        pptId,
        userId,
        title: pptData.title || '未命名演示文稿',
        slidesCount: pptData.slides?.length || 0,
        createdAt: new Date().toISOString(),
        updatedAt: new Date().toISOString(),
        storageType: 'huggingface',
        size: JSON.stringify(pptData).length
      };
      
      const metaFile = path.join(pptDir, 'meta.json');
      await fs.writeFile(metaFile, JSON.stringify(metadata, null, 2));
      
      console.log(`✅ PPT data stored to Huggingface: ${pptId} for user ${userId}`);
      return {
        success: true,
        pptId,
        metadata
      };
    } catch (error) {
      console.error(`❌ Failed to store PPT data ${pptId}:`, error);
      throw error;
    }
  }

  /**
   * 从Huggingface硬盘获取PPT数据
   * @param {string} userId - 用户ID
   * @param {string} pptId - PPT ID
   * @returns {Promise<Object>} PPT数据
   */
  async getPPTData(userId, pptId) {
    if (!this.initialized) {
      await this.initialize();
    }

    try {
      const pptDataFile = path.join(this.usersDir, userId, pptId, 'data.json');
      const data = await fs.readFile(pptDataFile, 'utf-8');
      const pptData = JSON.parse(data);
      
      console.log(`✅ PPT data loaded from Huggingface: ${pptId} for user ${userId}`);
      return pptData;
    } catch (error) {
      console.error(`❌ Failed to get PPT data ${pptId}:`, error);
      throw error;
    }
  }

  /**
   * 获取用户的PPT列表
   * @param {string} userId - 用户ID
   * @returns {Promise<Array>} PPT列表
   */
  async getUserPPTList(userId) {
    if (!this.initialized) {
      await this.initialize();
    }

    try {
      const userDir = path.join(this.usersDir, userId);
      
      // 检查用户目录是否存在
      try {
        await fs.access(userDir);
      } catch {
        console.log(`📁 No PPTs found for user ${userId} in Huggingface storage`);
        return [];
      }
      
      const pptFolders = await fs.readdir(userDir, { withFileTypes: true });
      const pptList = [];
      
      for (const folder of pptFolders) {
        if (folder.isDirectory()) {
          try {
            const metaFile = path.join(userDir, folder.name, 'meta.json');
            const metaData = await fs.readFile(metaFile, 'utf-8');
            const metadata = JSON.parse(metaData);
            
            pptList.push({
              name: folder.name,
              title: metadata.title || '未命名演示文稿',
              updatedAt: metadata.updatedAt || new Date().toISOString(),
              slidesCount: metadata.slidesCount || 0,
              storageType: 'huggingface',
              size: metadata.size || 0,
              repoUrl: 'Huggingface Storage'
            });
          } catch (error) {
            console.warn(`⚠️ Skipping invalid PPT folder ${folder.name}:`, error.message);
          }
        }
      }
      
      console.log(`📁 Found ${pptList.length} PPTs in Huggingface storage for user ${userId}`);
      return pptList.sort((a, b) => new Date(b.updatedAt) - new Date(a.updatedAt));
    } catch (error) {
      console.error(`❌ Failed to get PPT list for user ${userId}:`, error);
      throw error;
    }
  }

  /**
   * 删除PPT数据
   * @param {string} userId - 用户ID
   * @param {string} pptId - PPT ID
   * @returns {Promise<boolean>} 删除结果
   */
  async deletePPTData(userId, pptId) {
    if (!this.initialized) {
      await this.initialize();
    }

    try {
      const pptDir = path.join(this.usersDir, userId, pptId);
      
      // 递归删除PPT目录
      await fs.rm(pptDir, { recursive: true, force: true });
      
      console.log(`✅ PPT data deleted from Huggingface: ${pptId} for user ${userId}`);
      return true;
    } catch (error) {
      console.error(`❌ Failed to delete PPT data ${pptId}:`, error);
      return false;
    }
  }

  /**
   * 获取用户的所有图片
   * @param {string} userId - 用户ID
   * @param {string} pptId - PPT ID (可选)
   * @returns {Promise<Array>} 图片列表
   */
  async getUserImages(userId, pptId = null) {
    if (!this.initialized) {
      await this.initialize();
    }

    const userImages = [];
    
    for (const [imageId, linkInfo] of this.linkMap.entries()) {
      if (linkInfo.userId === userId) {
        if (!pptId || linkInfo.pptId === pptId) {
          userImages.push({
            imageId,
            pptId: linkInfo.pptId,
            pageIndex: linkInfo.pageIndex,
            version: linkInfo.version,
            format: linkInfo.format,
            size: linkInfo.size,
            url: `/api/images/${imageId}`,
            createdAt: linkInfo.createdAt,
            updatedAt: linkInfo.updatedAt
          });
        }
      }
    }
    
    return userImages.sort((a, b) => {
      if (a.pptId !== b.pptId) {
        return a.pptId.localeCompare(b.pptId);
      }
      return a.pageIndex - b.pageIndex;
    });
  }

  /**
   * 清理过期图片
   * @param {number} maxAge - 最大保留时间（毫秒）
   * @returns {Promise<number>} 清理的图片数量
   */
  async cleanupExpiredImages(maxAge = 30 * 24 * 60 * 60 * 1000) { // 默认30天
    if (!this.initialized) {
      await this.initialize();
    }

    const now = Date.now();
    let cleanedCount = 0;
    
    for (const [imageId, linkInfo] of this.linkMap.entries()) {
      const createdAt = new Date(linkInfo.createdAt).getTime();
      if (now - createdAt > maxAge) {
        await this.deleteImage(imageId);
        cleanedCount++;
      }
    }
    
    console.log(`🧹 Cleaned up ${cleanedCount} expired images`);
    return cleanedCount;
  }



  /**
   * 获取存储统计信息
   * @returns {Promise<Object>} 统计信息
   */
  async getStorageStats() {
    if (!this.initialized) {
      await this.initialize();
    }

    let totalSize = 0;
    let totalImages = 0;
    const userStats = {};
    
    // 从内存存储中统计
    for (const [imageId, metadata] of this.metadataMap.entries()) {
      totalSize += metadata.size || 0;
      totalImages++;
      
      if (!userStats[metadata.userId]) {
        userStats[metadata.userId] = {
          imageCount: 0,
          totalSize: 0,
          ppts: new Set()
        };
      }
      
      userStats[metadata.userId].imageCount++;
      userStats[metadata.userId].totalSize += metadata.size || 0;
      userStats[metadata.userId].ppts.add(metadata.pptId);
    }
    
    // 转换Set为数组
    for (const userId in userStats) {
      userStats[userId].pptCount = userStats[userId].ppts.size;
      delete userStats[userId].ppts;
    }
    
    return {
      totalImages,
      totalSize,
      totalSizeMB: Math.round(totalSize / 1024 / 1024 * 100) / 100,
      userCount: Object.keys(userStats).length,
      userStats,
      memoryUsage: {
        current: this.currentMemoryUsage,
        max: this.maxMemoryUsage,
        currentMB: Math.round(this.currentMemoryUsage / 1024 / 1024 * 100) / 100,
        maxGB: Math.round(this.maxMemoryUsage / 1024 / 1024 / 1024 * 100) / 100,
        percentage: Math.round(this.currentMemoryUsage / this.maxMemoryUsage * 100 * 100) / 100,
        imagesInMemory: this.memoryStorage.size
      }
    };
  }

  /**
   * 获取内存使用情况
   * @returns {Object} 内存使用统计
   */
  getMemoryUsage() {
    return {
      current: this.currentMemoryUsage,
      max: this.maxMemoryUsage,
      currentMB: Math.round(this.currentMemoryUsage / 1024 / 1024 * 100) / 100,
      maxGB: Math.round(this.maxMemoryUsage / 1024 / 1024 / 1024 * 100) / 100,
      percentage: Math.round(this.currentMemoryUsage / this.maxMemoryUsage * 100 * 100) / 100,
      imagesInMemory: this.memoryStorage.size,
      metadataCount: this.metadataMap.size,
      userCount: this.userDataMap.size
    };
  }

  /**
   * 清空所有内存数据
   */
  clearAllMemory() {
    this.memoryStorage.clear();
    this.metadataMap.clear();
    this.linkMap.clear();
    this.userDataMap.clear();
    this.currentMemoryUsage = 0;
    
    console.log('🧹 All memory data cleared');
  }

  /**
   * 健康检查
   */
  async healthCheck() {
    try {
      if (!this.initialized) {
        return {
          status: 'unhealthy',
          message: 'Service not initialized',
          details: {
            initialized: false,
            memoryUsage: 0,
            imagesCount: 0
          }
        };
      }

      // 检查内存使用情况
      const memoryUsage = this.getMemoryUsage();
      const isMemoryHealthy = memoryUsage.percentage < 90; // 90%以下认为健康

      // 检查数据目录是否可访问
      let dirAccessible = true;
      try {
        await fs.access(this.usersDir);
      } catch (error) {
        dirAccessible = false;
      }

      const isHealthy = isMemoryHealthy && dirAccessible;

      return {
        status: isHealthy ? 'healthy' : 'unhealthy',
        message: isHealthy 
          ? 'Huggingface Storage Service is running normally'
          : 'Service has issues',
        details: {
          initialized: this.initialized,
          memoryUsage: memoryUsage,
          dirAccessible: dirAccessible,
          usersDir: this.usersDir,
          isMemoryHealthy: isMemoryHealthy,
          maxMemoryUsageGB: Math.round(this.maxMemoryUsage / 1024 / 1024 / 1024 * 100) / 100,
          cleanupThreshold: this.cleanupThreshold
        }
      };
    } catch (error) {
      return {
        status: 'unhealthy',
        message: 'Health check failed',
        details: {
          error: error.message,
          stack: error.stack
        }
      };
    }
  }

  /**
   * 获取用户的图片列表
   * @param {string} userId - 用户ID
   * @returns {Array} 用户的图片列表
   */
  getUserImageList(userId) {
    const userImages = [];
    
    for (const [imageId, metadata] of this.metadataMap.entries()) {
      if (metadata.userId === userId) {
        userImages.push({
          imageId,
          pptId: metadata.pptId,
          pageIndex: metadata.pageIndex,
          format: metadata.format,
          size: metadata.size,
          createdAt: metadata.createdAt,
          version: metadata.version
        });
      }
    }
    
    return userImages;
  }

  /**
   * 获取PPT的所有图片
   * @param {string} userId - 用户ID
   * @param {string} pptId - PPT ID
   * @returns {Array} PPT的图片列表
   */
  getPPTImages(userId, pptId) {
    const pptImages = [];
    
    for (const [imageId, metadata] of this.metadataMap.entries()) {
      if (metadata.userId === userId && metadata.pptId === pptId) {
        pptImages.push({
          imageId,
          pageIndex: metadata.pageIndex,
          format: metadata.format,
          size: metadata.size,
          createdAt: metadata.createdAt,
          version: metadata.version,
          url: `/api/images/${imageId}`
        });
      }
    }
    
    return pptImages.sort((a, b) => a.pageIndex - b.pageIndex);
  }

  /**
   * 公开访问：根据用户ID、PPT ID和页面索引获取图片
   * @param {string} userId - 用户ID
   * @param {string} pptId - PPT ID
   * @param {number} pageIndex - 页面索引
   * @returns {Promise<Object>} 图片数据和元信息
   */
  async getPublicImage(userId, pptId, pageIndex) {
    if (!this.initialized) {
      await this.initialize();
    }

    // 生成图片ID
    const imageId = this.generateImageId(userId, pptId, pageIndex, 'latest');
    
    // 从内存中获取图片数据
    const imageBuffer = this.memoryStorage.get(imageId);
    if (!imageBuffer) {
      throw new Error(`Public image not found: ${userId}/${pptId}/${pageIndex}`);
    }

    // 获取元数据
    const metadata = this.metadataMap.get(imageId);
    if (!metadata) {
      throw new Error(`Public image metadata not found: ${userId}/${pptId}/${pageIndex}`);
    }

    console.log(`✅ Public image accessed: ${userId}/${pptId}/${pageIndex} (${imageBuffer.length} bytes)`);
    
    return {
      success: true,
      data: imageBuffer,
      metadata: {
        imageId,
        userId,
        pptId,
        pageIndex,
        format: metadata.format,
        size: metadata.size,
        createdAt: metadata.createdAt,
        updatedAt: metadata.updatedAt,
        version: metadata.version,
        memoryStored: true
      }
    };
  }

  /**
   * 公开访问：检查图片是否存在
   * @param {string} userId - 用户ID
   * @param {string} pptId - PPT ID
   * @param {number} pageIndex - 页面索引
   * @returns {boolean} 图片是否存在
   */
  hasPublicImage(userId, pptId, pageIndex) {
    if (!this.initialized) {
      return false;
    }

    const imageId = this.generateImageId(userId, pptId, pageIndex, 'latest');
    return this.memoryStorage.has(imageId) && this.metadataMap.has(imageId);
  }

  /**
   * 公开访问：获取用户的PPT列表（仅包含有图片的PPT）
   * @param {string} userId - 用户ID
   * @returns {Array} PPT列表
   */
  getPublicPPTList(userId) {
    if (!this.initialized) {
      return [];
    }

    const pptMap = new Map();
    
    for (const [imageId, metadata] of this.metadataMap.entries()) {
      if (metadata.userId === userId) {
        if (!pptMap.has(metadata.pptId)) {
          pptMap.set(metadata.pptId, {
            pptId: metadata.pptId,
            userId: metadata.userId,
            pageCount: 0,
            totalSize: 0,
            createdAt: metadata.createdAt,
            updatedAt: metadata.updatedAt,
            pages: []
          });
        }
        
        const pptInfo = pptMap.get(metadata.pptId);
        pptInfo.pageCount++;
        pptInfo.totalSize += metadata.size;
        pptInfo.pages.push({
          pageIndex: metadata.pageIndex,
          format: metadata.format,
          size: metadata.size,
          url: `/api/public/image/${userId}/${metadata.pptId}/${metadata.pageIndex}`
        });
        
        // 更新最新时间
        if (new Date(metadata.updatedAt) > new Date(pptInfo.updatedAt)) {
          pptInfo.updatedAt = metadata.updatedAt;
        }
      }
    }
    
    // 排序页面并返回结果
    const result = Array.from(pptMap.values());
    result.forEach(ppt => {
      ppt.pages.sort((a, b) => a.pageIndex - b.pageIndex);
    });
    
    return result.sort((a, b) => new Date(b.updatedAt) - new Date(a.updatedAt));
  }
}

// 创建单例实例
const huggingfaceStorageService = new HuggingfaceStorageService();

export default huggingfaceStorageService;