backend/src/routes/public.js

import express from 'express';
import githubService from '../services/githubService.js';
import screenshotService from '../services/screenshotService.js';
// 修正导入路径：从 backend/src 向上两级到 app，再进入 shared
import { generateSlideHTML, generateExportPage, exportPPTToJSON, generateHTMLPresentation } from '../../../shared/export-utils.js';

const router = express.Router();

// 前端导出图片功能已移除，直接使用screenshotService

// 辅助函数：生成SVG - 改进版，支持更精确的PPT渲染
function generateSlideSVG(slide, pptData, options = {}) {
  const { width = 1000, height = 562 } = options;
  
  // 处理背景
  let backgroundStyle = '#ffffff';
  if (slide.background) {
    if (slide.background.type === 'solid') {
      backgroundStyle = slide.background.color || '#ffffff';
    } else if (slide.background.type === 'gradient' && slide.background.gradient) {
      // SVG渐变处理
      const colors = slide.background.gradient.colors || [];
      if (colors.length > 0) {
        backgroundStyle = colors[0].color || '#ffffff';
      }
    }
  }
  
  // 生成渐变定义（如果需要）
  let gradientDefs = '';
  if (slide.background?.type === 'gradient' && slide.background.gradient?.colors) {
    const colors = slide.background.gradient.colors;
    const gradientId = 'bg-gradient';
    if (slide.background.gradient.type === 'linear') {
      gradientDefs = `
        <defs>
          <linearGradient id="${gradientId}" x1="0%" y1="0%" x2="100%" y2="0%"> 
            ${colors.map((color, index) => 
              `<stop offset="${(index / (colors.length - 1)) * 100}%" style="stop-color:${color.color};stop-opacity:1" />`
            ).join('')}
          </linearGradient>
        </defs>
      `;
      backgroundStyle = `url(#${gradientId})`;
    }
  }
  
  // 渲染元素
  const elementsHTML = slide.elements.map(element => {
    const x = element.left || 0;
    const y = element.top || 0;
    const w = element.width || 100;
    const h = element.height || 100;
    const rotation = element.rotate || 0;
    
    // 变换属性
    const transform = rotation !== 0 ? `transform="rotate(${rotation} ${x + w/2} ${y + h/2})"` : '';
    
    if (element.type === 'text') {
      const fontSize = element.fontSize || 16;
      const fontFamily = element.fontName || 'Arial, sans-serif';
      const color = element.defaultColor || element.color || '#000000';
      const fontWeight = element.bold ? 'bold' : 'normal';
      const fontStyle = element.italic ? 'italic' : 'normal';
      const textDecoration = element.underline ? 'underline' : 'none';
      const textAnchor = element.align === 'center' ? 'middle' : element.align === 'right' ? 'end' : 'start';
      
      // 计算文本位置
      let textX = x + 10;
      if (element.align === 'center') textX = x + w/2;
      else if (element.align === 'right') textX = x + w - 10;
      
      // 处理多行文本
      const content = (element.content || '').replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;');
      const lines = content.split('\n');
      
      return `
        <g ${transform}>
          ${lines.map((line, index) => `
            <text x="${textX}" y="${y + fontSize + (index * fontSize * 1.2)}" 
                  font-family="${fontFamily}" 
                  font-size="${fontSize}" 
                  fill="${color}" 
                  font-weight="${fontWeight}"
                  font-style="${fontStyle}" 
                  text-decoration="${textDecoration}"
                  text-anchor="${textAnchor}">${line}</text>
          `).join('')}
        </g>
      `;
    }
    
    if (element.type === 'shape') {
      const fill = element.fill || '#cccccc';
      const stroke = element.outline?.color || 'none';
      const strokeWidth = element.outline?.width || 0;
      
      if (element.shape === 'ellipse') {
        const cx = x + w/2;
        const cy = y + h/2;
        const rx = w/2;
        const ry = h/2;
        return `<ellipse cx="${cx}" cy="${cy}" rx="${rx}" ry="${ry}" fill="${fill}" stroke="${stroke}" stroke-width="${strokeWidth}" ${transform}/>`;
      }
      
      // 默认矩形
      const borderRadius = element.borderRadius || 0;
      if (borderRadius > 0) {
        return `<rect x="${x}" y="${y}" width="${w}" height="${h}" rx="${borderRadius}" ry="${borderRadius}" fill="${fill}" stroke="${stroke}" stroke-width="${strokeWidth}" ${transform}/>`;
      }
      return `<rect x="${x}" y="${y}" width="${w}" height="${h}" fill="${fill}" stroke="${stroke}" stroke-width="${strokeWidth}" ${transform}/>`;
    }
    
    if (element.type === 'image' && element.src) {
      // 检查是否是base64图片
      if (element.src.startsWith('data:image/')) {
        return `<image x="${x}" y="${y}" width="${w}" height="${h}" href="${element.src}" ${transform}/>`;
      }
      // 外部图片 - 在SVG中可能有跨域问题，显示占位符
      return `<rect x="${x}" y="${y}" width="${w}" height="${h}" fill="#f0f0f0" stroke="#ccc" stroke-width="1" ${transform}/>
              <text x="${x + w/2}" y="${y + h/2}" text-anchor="middle" font-size="12" fill="#666">图片</text>`;
    }
    
    return '';
  }).filter(Boolean).join('');
  
  return `<svg width="${width}" height="${height}" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
    ${gradientDefs}
    <rect width="100%" height="100%" fill="${backgroundStyle}"/>
    <g>${elementsHTML}</g>
  </svg>`;
}

// Generate error page for frontend display
function generateErrorPage(title, message) {
  return `
<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>${title} - PPT导出</title>
    <style>
        body {
            font-family: 'Microsoft YaHei', sans-serif;
            margin: 0;
            padding: 0;
            background: linear-gradient(135deg, #ff6b6b 0%, #feca57 100%);
            min-height: 100vh;
            display: flex;
            align-items: center;
            justify-content: center;
        }
        .error-container {
            background: white;
            padding: 40px;
            border-radius: 15px;
            box-shadow: 0 20px 40px rgba(0,0,0,0.1);
            text-align: center;
            max-width: 500px;
            margin: 20px;
        }
        .error-icon { font-size: 64px; margin-bottom: 20px; }
        .error-title { font-size: 24px; font-weight: bold; color: #333; margin-bottom: 15px; }
        .error-message { font-size: 16px; color: #666; line-height: 1.6; margin-bottom: 30px; }
        .error-actions { display: flex; gap: 15px; justify-content: center; }
        .btn {
            padding: 12px 24px;
            border: none;
            border-radius: 5px;
            font-size: 16px;
            cursor: pointer;
            text-decoration: none;
            display: inline-block;
            transition: all 0.3s;
        }
        .btn-primary { background: #4CAF50; color: white; }
        .btn-primary:hover { background: #45a049; }
        .btn-secondary { background: #f8f9fa; color: #333; border: 1px solid #ddd; }
        .btn-secondary:hover { background: #e9ecef; }
    </style>
</head>
<body>
    <div class="error-container">
        <div class="error-icon">❌</div>
        <div class="error-title">${title}</div>
        <div class="error-message">${message}</div>
        <div class="error-actions">
            <button class="btn btn-secondary" onclick="history.back()">返回上页</button>
            <a href="/" class="btn btn-primary">回到首页</a>
        </div>
    </div>
</body>
</html>
  `;
}

// Publicly access PPT page - return HTML page
router.get('/view/:userId/:pptId/:slideIndex?', async (req, res, next) => {
  try {
    const { userId, pptId, slideIndex = 0 } = req.params;
    const querySlideIndex = req.query.slide ? parseInt(req.query.slide) : parseInt(slideIndex);
    const fileName = `${pptId}.json`;

    let pptData = null;
    
    // Try all GitHub repositories
    for (let i = 0; i < githubService.repositories.length; i++) {
      try {
        const result = await githubService.getFile(userId, fileName, i);
        if (result) {
          pptData = result.content;
          break;
        }
      } catch (error) {
        continue;
      }
    }

    if (!pptData) {
      return res.status(404).send(generateErrorPage('PPT Not Found', 'Please check if the link is correct'));
    }

    const slideIdx = querySlideIndex;
    if (slideIdx >= pptData.slides.length || slideIdx < 0) {
      return res.status(404).send(generateErrorPage('Slide Not Found', 'Please check if the slide index is correct'));
    }

    // 使用共享模块生成HTML
    const htmlContent = generateSlideHTML(pptData, slideIdx, { format: 'view' });
    res.setHeader('Content-Type', 'text/html; charset=utf-8');
    res.send(htmlContent);
  } catch (error) {
    next(error);
  }
});

// API endpoint: Get PPT data and specified slide (JSON format)
router.get('/api-view/:userId/:pptId/:slideIndex?', async (req, res, next) => {
  try {
    const { userId, pptId, slideIndex = 0 } = req.params;
    const fileName = `${pptId}.json`;

    let pptData = null;
    
    // Try all GitHub repositories
    for (let i = 0; i < githubService.repositories.length; i++) {
      try {
        const result = await githubService.getFile(userId, fileName, i);
        if (result) {
          pptData = result.content;
          break;
        }
      } catch (error) {
        continue;
      }
    }

    if (!pptData) {
      return res.status(404).json({ error: 'PPT not found' });
    }

    const slideIdx = parseInt(slideIndex);
    
    // 验证 slideIndex 是否为有效数字
    if (isNaN(slideIdx)) {
      console.log(`❌ Invalid slide index format: ${slideIndex}`);
      
      if (format === 'svg') {
        const invalidIndexSvg = `<svg width="800" height="450" xmlns="http://www.w3.org/2000/svg">
          <rect width="100%" height="100%" fill="#f8f9fa"/>
          <text x="400" y="200" text-anchor="middle" font-family="Arial, sans-serif" font-size="24" fill="#6c757d">Invalid Slide Index</text>
          <text x="400" y="250" text-anchor="middle" font-family="Arial, sans-serif" font-size="16" fill="#6c757d">Slide index "${slideIndex}" is not a valid number</text>
          <text x="400" y="300" text-anchor="middle" font-family="Arial, sans-serif" font-size="12" fill="#999">${new Date().toISOString()}</text>
        </svg>`;
        
        res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
        return res.send(invalidIndexSvg);
      } else {
        const errorPage = generateErrorPage('Invalid Slide Index', `Slide index "${slideIndex}" is not a valid number.`);
        res.setHeader('Content-Type', 'text/html; charset=utf-8');
        return res.status(400).send(errorPage);
      }
    }
    
    // 安全检查：确保 slides 数组存在
    if (!pptData.slides || !Array.isArray(pptData.slides)) {
      console.log(`❌ Invalid PPT data: slides array not found`);
      
      if (format === 'svg') {
        const invalidDataSvg = `<svg width="800" height="450" xmlns="http://www.w3.org/2000/svg">
          <rect width="100%" height="100%" fill="#f8f9fa"/>
          <text x="400" y="200" text-anchor="middle" font-family="Arial, sans-serif" font-size="24" fill="#6c757d">Invalid PPT Data</text>
          <text x="400" y="250" text-anchor="middle" font-family="Arial, sans-serif" font-size="16" fill="#6c757d">Slides data not found</text>
          <text x="400" y="300" text-anchor="middle" font-family="Arial, sans-serif" font-size="12" fill="#999">${new Date().toISOString()}</text>
        </svg>`;
        
        res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
        return res.send(invalidDataSvg);
      } else {
        const errorPage = generateErrorPage('Invalid PPT Data', 'PPT slides data not found or corrupted.');
        res.setHeader('Content-Type', 'text/html; charset=utf-8');
        return res.status(400).send(errorPage);
      }
    }
    
    if (slideIdx >= pptData.slides.length || slideIdx < 0) {
      return res.status(404).json({ error: 'Slide not found' });
    }

    // Return PPT data and specified slide
    res.json({
      id: pptData.id,
      title: pptData.title,
      theme: pptData.theme,
      currentSlide: pptData.slides[slideIdx],
      slideIndex: slideIdx,
      totalSlides: pptData.slides.length,
      isPublicView: true
    });
  } catch (error) {
    next(error);
  }
});

// Get complete PPT data (read-only mode)
router.get('/ppt/:userId/:pptId', async (req, res, next) => {
  try {
    const { userId, pptId } = req.params;
    const fileName = `${pptId}.json`;

    let pptData = null;
    
    // Try all GitHub repositories
    for (let i = 0; i < githubService.repositories.length; i++) {
      try {
        const result = await githubService.getFile(userId, fileName, i);
        if (result) {
          pptData = result.content;
          break;
        }
      } catch (error) {
        continue;
      }
    }

    if (!pptData) {
      return res.status(404).json({ error: 'PPT not found' });
    }

    // Return read-only version of PPT data
    res.json({
      ...pptData,
      isPublicView: true,
      readOnly: true
    });
  } catch (error) {
    next(error);
  }
});

// Generate PPT share link
router.post('/generate-share-link', async (req, res, next) => {
  try {
    const { userId, pptId, slideIndex = 0 } = req.body;

    if (!userId || !pptId) {
      return res.status(400).json({ error: 'User ID and PPT ID are required' });
    }

    console.log(`Generating share link for PPT: ${pptId}, User: ${userId}`);

    // Verify if PPT exists
    const fileName = `${pptId}.json`;
    let pptExists = false;
    let pptData = null;
    
    console.log(`Checking ${githubService.repositories.length} GitHub repositories...`);
    
    for (let i = 0; i < githubService.repositories.length; i++) {
      try {
        console.log(`Checking repository ${i}: ${githubService.repositories[i]}`);
        const result = await githubService.getFile(userId, fileName, i);
        if (result) {
          pptExists = true;
          pptData = result.content;
          console.log(`PPT found in repository ${i}`);
          break;
        }
      } catch (error) {
        console.log(`PPT not found in repository ${i}: ${error.message}`);
        continue;
      }
    }

    if (!pptExists) {
      return res.status(404).json({ 
        error: 'PPT not found',
        details: `PPT ${pptId} not found for user ${userId}`,
        searchedLocations: 'GitHub repositories'
      });
    }

    const baseUrl = process.env.PUBLIC_URL || req.get('host');
    // 修复协议判断：localhost 始终使用 http，生产环境使用 https
    const protocol = baseUrl.includes('localhost') ? 'http' : 'https';
    
    const shareLinks = {
      // Single page share link
      slideUrl: `${protocol}://${baseUrl}/api/public/view/${userId}/${pptId}/${slideIndex}`,
      // Complete PPT share link
      pptUrl: `${protocol}://${baseUrl}/api/public/ppt/${userId}/${pptId}`,
      // Frontend view link
      viewUrl: `${protocol}://${baseUrl}/public/${userId}/${pptId}/${slideIndex}`,
      // Screenshot link (直接返回图片)
      screenshotUrl: `${protocol}://${baseUrl}/api/public/image/${userId}/${pptId}/${slideIndex}?format=jpg&quality=90`,
      // 新增：直接图片URL (无需用户交互)
      directImageUrl: `${protocol}://${baseUrl}/api/public/direct-image/${userId}/${pptId}/${slideIndex}`,
      // Add PPT information
      pptInfo: {
        id: pptId,
        title: pptData?.title || 'Unknown Title',
        slideCount: pptData?.slides?.length || 0
      }
    };

    console.log('Share links generated successfully:', shareLinks);
    res.json(shareLinks);
  } catch (error) {
    next(error);
  }
});

// Screenshot endpoint - Frontend Export Strategy
router.get('/screenshot/:userId/:pptId/:slideIndex?', async (req, res, next) => {
  try {
    const { userId, pptId, slideIndex = 0 } = req.params;
    const { format = 'jpeg', quality = 90, strategy = 'frontend-first', returnHtml = 'true' } = req.query;
    
    console.log(`Screenshot request: userId=${userId}, pptId=${pptId}, slideIndex=${slideIndex}, strategy=${strategy}, returnHtml=${returnHtml}`);
    
    // Get PPT data
    const fileName = `${pptId}.json`;
    let pptData = null;
    
    // Try all GitHub repositories
    for (let i = 0; i < githubService.repositories.length; i++) {
      try {
        const result = await githubService.getFile(userId, fileName, i);
        if (result) {
          pptData = result.content;
          break;
        }
      } catch (error) {
        continue;
      }
    }

    if (!pptData) {
      return res.status(404).json({ error: 'PPT not found' });
    }

    // Check if slides array exists
    if (!pptData.slides || !Array.isArray(pptData.slides)) {
      return res.status(400).json({ error: 'Invalid PPT data: slides not found' });
    }

    const slideIdx = parseInt(slideIndex);
    
    // 安全检查：确保 slides 数组存在
    if (!pptData.slides || !Array.isArray(pptData.slides)) {
      console.log(`❌ Invalid PPT data: slides array not found`);
      
      if (format === 'svg') {
        const invalidDataSvg = `<svg width="800" height="450" xmlns="http://www.w3.org/2000/svg">
          <rect width="100%" height="100%" fill="#f8f9fa"/>
          <text x="400" y="200" text-anchor="middle" font-family="Arial, sans-serif" font-size="24" fill="#6c757d">Invalid PPT Data</text>
          <text x="400" y="250" text-anchor="middle" font-family="Arial, sans-serif" font-size="16" fill="#6c757d">Slides data not found</text>
          <text x="400" y="300" text-anchor="middle" font-family="Arial, sans-serif" font-size="12" fill="#999">${new Date().toISOString()}</text>
        </svg>`;
        
        res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
        return res.send(invalidDataSvg);
      } else {
        const errorPage = generateErrorPage('Invalid PPT Data', 'PPT slides data not found or corrupted.');
        res.setHeader('Content-Type', 'text/html; charset=utf-8');
        return res.status(400).send(errorPage);
      }
    }
    
    if (slideIdx >= pptData.slides.length || slideIdx < 0) {
      return res.status(404).json({ error: 'Invalid slide index' });
    }

    // Frontend Export Strategy - Return HTML page for client-side screenshot generation
    if (strategy === 'frontend-first' && returnHtml !== 'false') {
      console.log('Using frontend export strategy - returning HTML page');
      
      // 使用共享模块生成导出页面
      const htmlPage = generateExportPage(pptData, slideIdx, {
        format,
        quality: parseInt(quality),
        autoDownload: req.query.autoDownload === 'true'
      });
      
      res.setHeader('Content-Type', 'text/html; charset=utf-8');
      res.setHeader('X-Screenshot-Strategy', 'frontend-export');
      res.setHeader('X-Generation-Time', '< 100ms');
      return res.send(htmlPage);
    }

    // Fallback: Backend screenshot (if specifically requested)
    console.log('Using backend screenshot for direct image return...');
    
    // 使用共享模块生成HTML用于后端截图
    const htmlContent = generateSlideHTML(pptData, slideIdx, { format: 'screenshot' });
    
    try {
      const screenshot = await screenshotService.generateScreenshot(htmlContent, {
        format,
        quality: parseInt(quality),
        width: pptData.viewportSize || 1000,
        height: Math.ceil((pptData.viewportSize || 1000) * (pptData.viewportRatio || 0.5625))
      });
      
      res.setHeader('Content-Type', `image/${format}`);
      res.setHeader('X-Screenshot-Type', 'backend-generated');
      res.setHeader('X-Generation-Time', '2-5s');
      res.send(screenshot);
      
    } catch (error) {
      console.error('Backend screenshot failed:', error);
      
      // Generate fallback image
      const fallbackImage = screenshotService.generateFallbackImage(
        pptData.viewportSize || 1000, 
        Math.ceil((pptData.viewportSize || 1000) * (pptData.viewportRatio || 0.5625))
      );
      
      res.setHeader('Content-Type', `image/${format}`);
      res.setHeader('X-Screenshot-Type', 'fallback-generated');
      res.setHeader('X-Generation-Time', '< 50ms');
      res.send(fallbackImage);
    }
    
  } catch (error) {
    next(error);
  }
});

// 🔥 关键修改：image端点现在支持多种格式，包括SVG和JPG
router.get('/image/:userId/:pptId/:slideIndex?', async (req, res, next) => {
  try {
    const { userId, pptId, slideIndex = 0 } = req.params;
    const { format = 'svg', quality = 90, width: requestWidth, height: requestHeight } = req.query;
    
    console.log(`🔥 Image request: userId=${userId}, pptId=${pptId}, slideIndex=${slideIndex}, format=${format}`);
    
    // Get PPT data
    const fileName = `${pptId}.json`;
    let pptData = null;
    
    for (let i = 0; i < githubService.repositories.length; i++) {
      try {
        const result = await githubService.getFile(userId, fileName, i);
        if (result) {
          pptData = result.content;
          console.log(`✅ PPT data found in repository ${i}`);
          break;
        }
      } catch (error) {
        continue;
      }
    }

    if (!pptData) {
      console.log(`❌ PPT not found: ${pptId}`);
      
      if (format === 'svg') {
        const notFoundSvg = `<svg width="800" height="450" xmlns="http://www.w3.org/2000/svg">
          <rect width="100%" height="100%" fill="#f8f9fa"/>
          <text x="400" y="200" text-anchor="middle" font-family="Arial, sans-serif" font-size="24" fill="#6c757d">PPT Not Found</text>
          <text x="400" y="250" text-anchor="middle" font-family="Arial, sans-serif" font-size="16" fill="#6c757d">PPT ${pptId} does not exist</text>
          <text x="400" y="300" text-anchor="middle" font-family="Arial, sans-serif" font-size="12" fill="#999">${new Date().toISOString()}</text>
        </svg>`;
        
        res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
        return res.send(notFoundSvg);
      } else {
        // 对于JPG/PNG格式，返回截图工具页面
        const errorPage = generateErrorPage('PPT Not Found', `PPT ${pptId} not found. Please check the PPT ID.`);
        res.setHeader('Content-Type', 'text/html; charset=utf-8');
        return res.status(404).send(errorPage);
      }
    }

    const slideIdx = parseInt(slideIndex);
    
    // 安全检查：确保 slides 数组存在
    if (!pptData.slides || !Array.isArray(pptData.slides)) {
      console.log(`❌ Invalid PPT data: slides array not found`);
      
      if (format === 'svg') {
        const invalidDataSvg = `<svg width="800" height="450" xmlns="http://www.w3.org/2000/svg">
          <rect width="100%" height="100%" fill="#f8f9fa"/>
          <text x="400" y="200" text-anchor="middle" font-family="Arial, sans-serif" font-size="24" fill="#6c757d">Invalid PPT Data</text>
          <text x="400" y="250" text-anchor="middle" font-family="Arial, sans-serif" font-size="16" fill="#6c757d">Slides data not found</text>
          <text x="400" y="300" text-anchor="middle" font-family="Arial, sans-serif" font-size="12" fill="#999">${new Date().toISOString()}</text>
        </svg>`;
        
        res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
        return res.send(invalidDataSvg);
      } else {
        const errorPage = generateErrorPage('Invalid PPT Data', 'PPT slides data not found or corrupted.');
        res.setHeader('Content-Type', 'text/html; charset=utf-8');
        return res.status(400).send(errorPage);
      }
    }
    
    if (slideIdx >= pptData.slides.length || slideIdx < 0) {
      console.log(`❌ Invalid slide index: ${slideIndex}`);
      
      if (format === 'svg') {
        const invalidSlideSvg = `<svg width="800" height="450" xmlns="http://www.w3.org/2000/svg">
          <rect width="100%" height="100%" fill="#f8f9fa"/>
          <text x="400" y="200" text-anchor="middle" font-family="Arial, sans-serif" font-size="24" fill="#6c757d">Invalid Slide</text>
          <text x="400" y="250" text-anchor="middle" font-family="Arial, sans-serif" font-size="16" fill="#6c757d">Slide ${slideIndex} not found</text>
          <text x="400" y="300" text-anchor="middle" font-family="Arial, sans-serif" font-size="12" fill="#999">${new Date().toISOString()}</text>
        </svg>`;
        
        res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
        return res.send(invalidSlideSvg);
      } else {
        const errorPage = generateErrorPage('Invalid Slide', `Slide ${slideIndex} not found in this PPT.`);
        res.setHeader('Content-Type', 'text/html; charset=utf-8');
        return res.status(404).send(errorPage);
      }
    }

    // 根据格式处理
    if (format === 'svg') {
      // SVG格式 - 直接生成并返回
      console.log(`✅ Generating SVG for slide ${slideIdx}`);
      
      const defaultWidth = pptData.viewportSize || 1000;
      const defaultHeight = Math.ceil(defaultWidth * (pptData.viewportRatio || 0.5625));
      const finalWidth = requestWidth ? parseInt(requestWidth) : defaultWidth;
      const finalHeight = requestHeight ? parseInt(requestHeight) : defaultHeight;
      
      const slide = pptData.slides[slideIdx];
      const svgContent = generateSlideSVG(slide, pptData, { 
        width: finalWidth, 
        height: finalHeight 
      });
      
      console.log(`🎉 SVG generated successfully, returning image data`);
      
      res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
      res.setHeader('Cache-Control', 'no-cache, no-store, must-revalidate');
      res.setHeader('Access-Control-Allow-Origin', '*');
      res.setHeader('X-Force-Update', 'true');
      res.setHeader('X-Generation-Time', '< 10ms');
      res.send(svgContent);
      
    } else {
      // JPG/PNG格式 - 使用优化的截图方法
      console.log(`✅ Generating ${format} image using optimized screenshot method`);
      
      try {
        // 使用共享模块生成HTML用于后端截图
        const htmlContent = generateSlideHTML(pptData, slideIdx, { format: 'screenshot' });
        
        const screenshot = await screenshotService.generateScreenshot(htmlContent, {
          format: format === 'jpg' ? 'jpeg' : format,
          quality: parseInt(quality),
          width: pptData.viewportSize || 1000,
          height: Math.ceil((pptData.viewportSize || 1000) * (pptData.viewportRatio || 0.5625))
        });
        
        res.setHeader('Content-Type', `image/${format === 'jpg' ? 'jpeg' : format}`);
        res.setHeader('X-Screenshot-Type', 'backend-generated');
        res.setHeader('X-Generation-Time', '1-3s'); // 优化后的时间估计
        res.setHeader('Cache-Control', 'public, max-age=3600'); // 缓存1小时
        res.send(screenshot);
        
      } catch (error) {
        console.error(`Backend ${format} generation failed:`, error);
        
        // 生成后备图片
        const fallbackImage = screenshotService.generateFallbackImage(
          pptData.viewportSize || 1000, 
          Math.ceil((pptData.viewportSize || 1000) * (pptData.viewportRatio || 0.5625)),
          `PPT ${format.toUpperCase()} Image`,
          'Image generation failed'
        );
        
        res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
        res.setHeader('X-Screenshot-Type', 'fallback-generated');
        res.setHeader('X-Generation-Time', '< 50ms');
        res.send(fallbackImage);
      }
    }
    
  } catch (error) {
    console.error('❌ Image generation failed:', error);
    
    // 根据格式返回错误
    if (req.query.format === 'svg') {
      res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
      res.setHeader('Access-Control-Allow-Origin', '*');
      
      const errorSvg = `<svg width="800" height="450" xmlns="http://www.w3.org/2000/svg">
        <rect width="100%" height="100%" fill="#ffe6e6"/>
        <text x="400" y="200" text-anchor="middle" font-family="Arial, sans-serif" font-size="24" fill="#cc0000">Generation Error</text>
        <text x="400" y="250" text-anchor="middle" font-family="Arial, sans-serif" font-size="16" fill="#cc0000">Failed to generate image</text>
        <text x="400" y="300" text-anchor="middle" font-family="Arial, sans-serif" font-size="12" fill="#999">${new Date().toISOString()}</text>
      </svg>`;
      
      res.send(errorSvg);
    } else {
      const errorPage = generateErrorPage('Generation Error', 'Failed to generate the requested image format.');
      res.setHeader('Content-Type', 'text/html; charset=utf-8');
      res.status(500).send(errorPage);
    }
  }
});

// Screenshot data endpoint - For frontend direct rendering
router.get('/screenshot-data/:userId/:pptId/:slideIndex?', async (req, res, next) => {
  try {
    const { userId, pptId, slideIndex = 0 } = req.params;
    const { format = 'jpeg', quality = 90 } = req.query;
    
    console.log(`Screenshot data request: userId=${userId}, pptId=${pptId}, slideIndex=${slideIndex}`);
    
    // Get PPT data
    const fileName = `${pptId}.json`;
    let pptData = null;
    
    for (let i = 0; i < githubService.repositories.length; i++) {
      try {
        const result = await githubService.getFile(userId, fileName, i);
        if (result) {
          pptData = result.content;
          break;
        }
      } catch (error) {
        continue;
      }
    }

    if (!pptData) {
      return res.status(404).json({ error: 'PPT not found' });
    }

    // Check if slides array exists
    if (!pptData.slides || !Array.isArray(pptData.slides)) {
      return res.status(400).json({ error: 'Invalid PPT data: slides not found' });
    }

    const slideIdx = parseInt(slideIndex);
    
    // 安全检查：确保 slides 数组存在
    if (!pptData.slides || !Array.isArray(pptData.slides)) {
      console.log(`❌ Invalid PPT data: slides array not found`);
      
      if (format === 'svg') {
        const invalidDataSvg = `<svg width="800" height="450" xmlns="http://www.w3.org/2000/svg">
          <rect width="100%" height="100%" fill="#f8f9fa"/>
          <text x="400" y="200" text-anchor="middle" font-family="Arial, sans-serif" font-size="24" fill="#6c757d">Invalid PPT Data</text>
          <text x="400" y="250" text-anchor="middle" font-family="Arial, sans-serif" font-size="16" fill="#6c757d">Slides data not found</text>
          <text x="400" y="300" text-anchor="middle" font-family="Arial, sans-serif" font-size="12" fill="#999">${new Date().toISOString()}</text>
        </svg>`;
        
        res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
        return res.send(invalidDataSvg);
      } else {
        const errorPage = generateErrorPage('Invalid PPT Data', 'PPT slides data not found or corrupted.');
        res.setHeader('Content-Type', 'text/html; charset=utf-8');
        return res.status(400).send(errorPage);
      }
    }
    
    if (slideIdx >= pptData.slides.length || slideIdx < 0) {
      return res.status(404).json({ error: 'Invalid slide index' });
    }

    // Return PPT data for frontend rendering
    const responseData = {
      pptData: {
        id: pptData.id,
        title: pptData.title,
        theme: pptData.theme,
        viewportSize: pptData.viewportSize,
        viewportRatio: pptData.viewportRatio,
        slide: pptData.slides[slideIdx]
      },
      slideIndex: slideIdx,
      totalSlides: pptData.slides.length,
      exportConfig: {
        format,
        quality: parseInt(quality),
        width: pptData.viewportSize || 1000,
        height: Math.ceil((pptData.viewportSize || 1000) * (pptData.viewportRatio || 0.5625))
      },
      strategy: 'frontend-direct-rendering',
      timestamp: new Date().toISOString()
    };
    
    res.setHeader('X-Screenshot-Strategy', 'frontend-data-api');
    res.json(responseData);
    
  } catch (error) {
    next(error);
  }
});

// Screenshot health check
router.get('/screenshot-health', async (req, res, next) => {
  try {
    const status = {
      status: 'healthy',
      timestamp: new Date().toISOString(),
      environment: {
        nodeEnv: process.env.NODE_ENV,
        isHuggingFace: process.env.SPACE_ID ? true : false,
        platform: process.platform
      },
      screenshotService: {
        available: true,
        strategy: 'frontend-first',
        backendFallback: false, // Disable backend browsers
        screenshotSize: 0
      }
    };

    // Test fallback image generation
    try {
      const testImage = screenshotService.generateFallbackImage(100, 100);
      status.screenshotService.screenshotSize = testImage.length;
      status.screenshotService.fallbackAvailable = true;
    } catch (error) {
      status.screenshotService.fallbackAvailable = false;
      status.screenshotService.fallbackError = error.message;
    }

    res.json(status);
  } catch (error) {
    res.status(500).json({
      status: 'error',
      timestamp: new Date().toISOString(),
      error: error.message
    });
  }
});

// 新增：截图工具页面端点（原来的image端点功能）
router.get('/screenshot-tool/:userId/:pptId/:slideIndex?', async (req, res, next) => {
  try {
    const { userId, pptId, slideIndex = 0 } = req.params;
    const { format = 'jpeg', quality = 90 } = req.query;
    
    console.log(`Screenshot tool request: userId=${userId}, pptId=${pptId}, slideIndex=${slideIndex}`);
    
    // Get PPT data
    const fileName = `${pptId}.json`;
    let pptData = null;
    
    for (let i = 0; i < githubService.repositories.length; i++) {
      try {
        const result = await githubService.getFile(userId, fileName, i);
        if (result) {
          pptData = result.content;
          console.log(`✅ PPT data found in repository ${i}`);
          break;
        }
      } catch (error) {
        continue;
      }
    }

    if (!pptData) {
      const errorPage = generateErrorPage('PPT Not Found', `PPT ${pptId} not found for user ${userId}`);
      res.setHeader('Content-Type', 'text/html; charset=utf-8');
      return res.status(404).send(errorPage);
    }

    const slideIdx = parseInt(slideIndex);
    
    // 安全检查：确保 slides 数组存在
    if (!pptData.slides || !Array.isArray(pptData.slides)) {
      console.log(`❌ Invalid PPT data: slides array not found`);
      
      if (format === 'svg') {
        const invalidDataSvg = `<svg width="800" height="450" xmlns="http://www.w3.org/2000/svg">
          <rect width="100%" height="100%" fill="#f8f9fa"/>
          <text x="400" y="200" text-anchor="middle" font-family="Arial, sans-serif" font-size="24" fill="#6c757d">Invalid PPT Data</text>
          <text x="400" y="250" text-anchor="middle" font-family="Arial, sans-serif" font-size="16" fill="#6c757d">Slides data not found</text>
          <text x="400" y="300" text-anchor="middle" font-family="Arial, sans-serif" font-size="12" fill="#999">${new Date().toISOString()}</text>
        </svg>`;
        
        res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
        return res.send(invalidDataSvg);
      } else {
        const errorPage = generateErrorPage('Invalid PPT Data', 'PPT slides data not found or corrupted.');
        res.setHeader('Content-Type', 'text/html; charset=utf-8');
        return res.status(400).send(errorPage);
      }
    }
    
    if (slideIdx >= pptData.slides.length || slideIdx < 0) {
      const errorPage = generateErrorPage('Invalid Slide', `Slide ${slideIndex} not found in PPT`);
      res.setHeader('Content-Type', 'text/html; charset=utf-8');
      return res.status(404).send(errorPage);
    }

    // 使用共享模块生成导出页面
    const htmlPage = generateExportPage(pptData, slideIdx, {
      format,
      quality: parseInt(quality),
      autoDownload: false // 不自动下载，需要用户手动操作
    });
    
    res.setHeader('Content-Type', 'text/html; charset=utf-8');
    res.setHeader('X-Screenshot-Strategy', 'frontend-screenshot-tool');
    res.setHeader('X-Generation-Time', '< 50ms');
    res.send(htmlPage);
    
  } catch (error) {
    next(error);
  }
});

// 新增：PPT JSON导出端点
router.get('/export-json/:userId/:pptId', async (req, res, next) => {
  try {
    const { userId, pptId } = req.params;
    const fileName = `${pptId}.json`;

    let pptData = null;
    
    // Try all GitHub repositories
    for (let i = 0; i < githubService.repositories.length; i++) {
      try {
        const result = await githubService.getFile(userId, fileName, i);
        if (result) {
          pptData = result.content;
          break;
        }
      } catch (error) {
        continue;
      }
    }

    if (!pptData) {
      return res.status(404).json({ error: 'PPT not found' });
    }

    // 使用共享模块导出JSON
    const jsonData = exportPPTToJSON(pptData);
    
    res.setHeader('Content-Type', 'application/json; charset=utf-8');
    res.setHeader('Content-Disposition', `attachment; filename="${pptData.title || 'presentation'}.json"`);
    res.json(jsonData);
  } catch (error) {
    next(error);
  }
});

// 新增：PPT HTML演示文稿导出端点
router.get('/export-html/:userId/:pptId', async (req, res, next) => {
  try {
    const { userId, pptId } = req.params;
    const { interactive = 'true', standalone = 'true', css = 'true' } = req.query;
    const fileName = `${pptId}.json`;

    let pptData = null;
    
    // Try all GitHub repositories
    for (let i = 0; i < githubService.repositories.length; i++) {
      try {
        const result = await githubService.getFile(userId, fileName, i);
        if (result) {
          pptData = result.content;
          break;
        }
      } catch (error) {
        continue;
      }
    }

    if (!pptData) {
      return res.status(404).json({ error: 'PPT not found' });
    }

    // 使用共享模块生成完整HTML演示文稿
    const htmlContent = generateHTMLPresentation(pptData, {
      includeInteractivity: interactive === 'true',
      standalone: standalone === 'true',
      includeCSS: css === 'true'
    });
    
    res.setHeader('Content-Type', 'text/html; charset=utf-8');
    res.setHeader('Content-Disposition', `attachment; filename="${pptData.title || 'presentation'}.html"`);
    res.send(htmlContent);
  } catch (error) {
    next(error);
  }
});

// 新增：PPT完整演示文稿查看端点（在线查看，非下载）
router.get('/presentation/:userId/:pptId', async (req, res, next) => {
  try {
    const { userId, pptId } = req.params;
    const fileName = `${pptId}.json`;

    let pptData = null;
    
    // Try all GitHub repositories
    for (let i = 0; i < githubService.repositories.length; i++) {
      try {
        const result = await githubService.getFile(userId, fileName, i);
        if (result) {
          pptData = result.content;
          break;
        }
      } catch (error) {
        continue;
      }
    }

    if (!pptData) {
      return res.status(404).send(generateErrorPage('PPT Not Found', 'The presentation you are looking for does not exist.'));
    }

    // 使用共享模块生成完整HTML演示文稿用于在线查看
    const htmlContent = generateHTMLPresentation(pptData, {
      includeInteractivity: true,
      standalone: true,
      includeCSS: true
    });
    
    res.setHeader('Content-Type', 'text/html; charset=utf-8');
    res.send(htmlContent);
  } catch (error) {
    next(error);
  }
});

// 新增：直接返回图片的端点 - 必须放在其他路由之前避免被覆盖
router.get('/direct-image/:userId/:pptId/:slideIndex?', async (req, res, next) => {
  try {
    const { userId, pptId, slideIndex = 0 } = req.params;
    const { format = 'svg', quality = 90, width: requestWidth, height: requestHeight } = req.query;
    
    console.log(`🖼️ Direct image request: userId=${userId}, pptId=${pptId}, slideIndex=${slideIndex}, format=${format}`);
    
    // Get PPT data
    const fileName = `${pptId}.json`;
    let pptData = null;
    
    for (let i = 0; i < githubService.repositories.length; i++) {
      try {
        const result = await githubService.getFile(userId, fileName, i);
        if (result) {
          pptData = result.content;
          console.log(`✅ PPT data found in repository ${i}`);
          break;
        }
      } catch (error) {
        continue;
      }
    }

    if (!pptData) {
      console.log(`❌ PPT not found: ${pptId}`);
      // 返回404图片SVG
      const notFoundSvg = `<svg width="800" height="450" xmlns="http://www.w3.org/2000/svg">
        <rect width="100%" height="100%" fill="#f8f9fa"/>
        <text x="400" y="200" text-anchor="middle" font-family="Arial, sans-serif" font-size="24" fill="#6c757d">PPT Not Found</text>
        <text x="400" y="250" text-anchor="middle" font-family="Arial, sans-serif" font-size="16" fill="#6c757d">PPT ${pptId} does not exist</text>
      </svg>`;
      
      res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
      res.setHeader('Cache-Control', 'no-cache');
      res.setHeader('Access-Control-Allow-Origin', '*');
      return res.send(notFoundSvg);
    }

    const slideIdx = parseInt(slideIndex);
    
    // 安全检查：确保 slides 数组存在
    if (!pptData.slides || !Array.isArray(pptData.slides)) {
      console.log(`❌ Invalid PPT data: slides array not found`);
      
      if (format === 'svg') {
        const invalidDataSvg = `<svg width="800" height="450" xmlns="http://www.w3.org/2000/svg">
          <rect width="100%" height="100%" fill="#f8f9fa"/>
          <text x="400" y="200" text-anchor="middle" font-family="Arial, sans-serif" font-size="24" fill="#6c757d">Invalid PPT Data</text>
          <text x="400" y="250" text-anchor="middle" font-family="Arial, sans-serif" font-size="16" fill="#6c757d">Slides data not found</text>
          <text x="400" y="300" text-anchor="middle" font-family="Arial, sans-serif" font-size="12" fill="#999">${new Date().toISOString()}</text>
        </svg>`;
        
        res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
        return res.send(invalidDataSvg);
      } else {
        const errorPage = generateErrorPage('Invalid PPT Data', 'PPT slides data not found or corrupted.');
        res.setHeader('Content-Type', 'text/html; charset=utf-8');
        return res.status(400).send(errorPage);
      }
    }
    
    if (slideIdx >= pptData.slides.length || slideIdx < 0) {
      console.log(`❌ Invalid slide index: ${slideIndex}`);
      // 返回404幻灯片SVG
      const invalidSlideSvg = `<svg width="800" height="450" xmlns="http://www.w3.org/2000/svg">
        <rect width="100%" height="100%" fill="#f8f9fa"/>
        <text x="400" y="200" text-anchor="middle" font-family="Arial, sans-serif" font-size="24" fill="#6c757d">Invalid Slide</text>
        <text x="400" y="250" text-anchor="middle" font-family="Arial, sans-serif" font-size="16" fill="#6c757d">Slide ${slideIndex} not found</text>
      </svg>`;
      
      res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
      res.setHeader('Cache-Control', 'no-cache');
      res.setHeader('Access-Control-Allow-Origin', '*');
      return res.send(invalidSlideSvg);
    }

    console.log(`✅ Generating SVG for slide ${slideIdx}`);
    
    // 计算图片尺寸
    const defaultWidth = pptData.viewportSize || 1000;
    const defaultHeight = Math.ceil(defaultWidth * (pptData.viewportRatio || 0.5625));
    const finalWidth = requestWidth ? parseInt(requestWidth) : defaultWidth;
    const finalHeight = requestHeight ? parseInt(requestHeight) : defaultHeight;
    
    // 生成PPT幻灯片的SVG图片
    const slide = pptData.slides[slideIdx];
    const svgContent = generateSlideSVG(slide, pptData, { 
      width: finalWidth, 
      height: finalHeight 
    });
    
    console.log(`✅ SVG generated successfully, size: ${svgContent.length} characters`);
    
    // 设置正确的响应头，使其可以被其他网站作为图片引用
    res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
    res.setHeader('Cache-Control', 'public, max-age=3600'); // 缓存1小时
    res.setHeader('Access-Control-Allow-Origin', '*'); // 允许跨域引用
    res.setHeader('X-Generation-Time', '< 10ms');
    res.setHeader('X-Content-Source', 'direct-svg-generation');
    res.setHeader('Content-Disposition', 'inline'); // 确保浏览器内联显示图片
    
    // 直接返回SVG图片内容
    res.send(svgContent);
    
  } catch (error) {
    console.error('❌ Direct image generation failed:', error);
    
    // 返回错误图片SVG
    const errorSvg = `<svg width="800" height="450" xmlns="http://www.w3.org/2000/svg">
      <rect width="100%" height="100%" fill="#ffe6e6"/>
      <text x="400" y="200" text-anchor="middle" font-family="Arial, sans-serif" font-size="24" fill="#cc0000">Generation Error</text>
      <text x="400" y="250" text-anchor="middle" font-family="Arial, sans-serif" font-size="16" fill="#cc0000">Failed to generate image: ${error.message}</text>
    </svg>`;
    
    res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
    res.setHeader('Cache-Control', 'no-cache');
    res.setHeader('Access-Control-Allow-Origin', '*');
    res.send(errorSvg);
  }
});

// 存储前端生成的图片数据
const imageCache = new Map();

// POST endpoint to receive frontend-generated images
router.post('/save-image/:userId/:pptId/:slideIndex', express.json({ limit: '10mb' }), async (req, res, next) => {
  try {
    const { userId, pptId, slideIndex } = req.params;
    const { imageData, format = 'jpeg', quality = 90 } = req.body;
    
    if (!imageData) {
      return res.status(400).json({ error: 'Image data is required' });
    }
    
    // 生成唯一的图片ID
    const imageId = `${userId}-${pptId}-${slideIndex}-${Date.now()}`;
    
    // 存储图片数据到内存缓存
    imageCache.set(imageId, {
      data: imageData,
      format,
      quality,
      userId,
      pptId,
      slideIndex,
      timestamp: new Date().toISOString(),
      contentType: `image/${format === 'jpg' ? 'jpeg' : format}`
    });
    
    // 设置过期时间（1小时后自动清理）
    setTimeout(() => {
      imageCache.delete(imageId);
    }, 3600000);
    
    // 返回图片访问URL
    const baseUrl = req.protocol + '://' + req.get('host');
    const imageUrl = `${baseUrl}/api/public/cached-image/${imageId}`;
    
    console.log(`✅ Image saved with ID: ${imageId}`);
    
    res.json({
      success: true,
      imageId,
      imageUrl,
      expiresAt: new Date(Date.now() + 3600000).toISOString()
    });
    
  } catch (error) {
    console.error('❌ Failed to save image:', error);
    next(error);
  }
});

// GET endpoint to serve cached images
router.get('/cached-image/:imageId', async (req, res, next) => {
  try {
    const { imageId } = req.params;
    
    const cachedImage = imageCache.get(imageId);
    if (!cachedImage) {
      return res.status(404).json({ error: 'Image not found or expired' });
    }
    
    // 设置响应头
    res.setHeader('Content-Type', cachedImage.contentType);
    res.setHeader('Cache-Control', 'public, max-age=3600');
    res.setHeader('Access-Control-Allow-Origin', '*');
    res.setHeader('X-Image-Source', 'frontend-generated');
    res.setHeader('X-Generation-Time', cachedImage.timestamp);
    
    // 如果是base64数据，需要转换
    if (cachedImage.data.startsWith('data:')) {
      const base64Data = cachedImage.data.split(',')[1];
      const buffer = Buffer.from(base64Data, 'base64');
      res.send(buffer);
    } else {
      res.send(cachedImage.data);
    }
    
  } catch (error) {
    console.error('❌ Failed to serve cached image:', error);
    next(error);
  }
});

export default router;