Datasets:

TwanAPI
/

DataNote

@@ -1,8 +1,8 @@
 {
   "id": "dcc43ef1-4f83-4afe-a59d-61a9ae99cb51",
   "title": "Untitled",
-  "content": "import express from 'express';\nimport { MongoClient, ObjectId } from 'mongodb';\nimport multer from 'multer';\nimport bcryptjs from 'bcryptjs';\nimport jwt from 'jsonwebtoken';\nimport fs from 'fs';\nimport path from 'path';\nimport { fileURLToPath } from 'url';\nimport dotenv from 'dotenv';\nimport cluster from 'cluster';\nimport os from 'os';\nimport compression from 'compression';\n\n// Load environment variables\ndotenv.config({ path: '.env.server' });\n\nconst __dirname = path.dirname(fileURLToPath(import.meta.url));\nconst uploadsDir = path.join(__dirname, 'uploads');\nconst tempChunksDir = path.join(__dirname, 'uploads_tmp');\n\nif (!fs.existsSync(uploadsDir)) {\n  fs.mkdirSync(uploadsDir, { recursive: true });\n}\n\nif (!fs.existsSync(tempChunksDir)) {\n  fs.mkdirSync(tempChunksDir, { recursive: true });\n}\n\nconst app = express();\nconst PORT = process.env.PORT || 3001;\nconst MONGODB_URI = process.env.MONGODB_URI || 'mongodb+srv://admin:Tuandzvcl@userupload.1zqgqci.mongodb.net/?appName=UserUpload';\nconst JWT_SECRET = process.env.JWT_SECRET || 'TwanDz';\n\n// Rate limiting per IP to prevent abuse\nconst requestCounts = new Map();\nconst RATE_LIMIT_WINDOW = 60000; // 1 minute\nconst MAX_REQUESTS_PER_WINDOW = 1500; // 1500 req/min supports 8 files × adaptive chunks\n\n// Cleanup request counts every 5 minutes\nsetInterval(() => {\n  requestCounts.clear();\n}, 5 * 60 * 1000);\n\n// Rate limiter middleware (skip for upload-chunk to allow fast uploads)\napp.use((req, res, next) => {\n  // Skip rate limiting for upload-chunk endpoint to allow high-speed parallel uploads\n  if (req.path === '/api/files/upload-chunk') {\n    return next();\n  }\n\n  const ip = req.ip;\n  const now = Date.now();\n  \n  if (!requestCounts.has(ip)) {\n    requestCounts.set(ip, []);\n  }\n  \n  const requests = requestCounts.get(ip);\n  const recentRequests = requests.filter(t => now - t < RATE_LIMIT_WINDOW);\n  \n  if (recentRequests.length >= MAX_REQUESTS_PER_WINDOW) {\n    return res.status(429).json({ error: 'Too many requests, please try again later' });\n  }\n  \n  recentRequests.push(now);\n  requestCounts.set(ip, recentRequests);\n  next();\n});\n\nlet db;\nlet mongoClient;\n\n// Track concurrent uploads\nconst uploadSessions = new Map(); // uploadId -> { chunks: Set, totalChunks, status }\n\n// Initialize MongoDB\nasync function initMongoDB() {\n  try {\n    console.log('🔄 Connecting to MongoDB...');\n    console.log('URI:', MONGODB_URI.replace(/:[^:]*@/, ':****@')); // Hide password in logs\n    \n    mongoClient = new MongoClient(MONGODB_URI, {\n      serverSelectionTimeoutMS: 5000,\n      connectTimeoutMS: 10000,\n      // HIGH-PERFORMANCE POOLING: Optimize connection reuse\n      maxPoolSize: 80, // Support 8 concurrent files × 10 chunks + parallelism\n      minPoolSize: 20, // Keep connections warm for burst uploads\n      maxIdleTimeMS: 45000, // Longer idle time reduces reconnection overhead\n      waitQueueTimeoutMS: 5000, // Faster timeout for better request queueing\n    });\n    \n    await mongoClient.connect();\n    console.log('✅ MongoDB connected successfully');\n    \n    db = mongoClient.db('file-caddy');\n\n    // Create collections if they don't exist\n    const collections = await db.listCollections().toArray();\n    const collectionNames = collections.map(c => c.name);\n\n    if (!collectionNames.includes('users')) {\n      await db.createCollection('users');\n      await db.collection('users').createIndex({ email: 1 }, { unique: true });\n      await db.collection('users').createIndex({ username: 1 }, { unique: true, sparse: true });\n      console.log('📦 Created users collection');\n    }\n    if (!collectionNames.includes('files')) {\n      await db.createCollection('files');\n      await db.collection('files').createIndex({ user_id: 1 });\n      console.log('📦 Created files collection');\n    }\n\n    console.log('✅ MongoDB fully initialized');\n  } catch (err) {\n    console.error('❌ MongoDB connection error:', err.message);\n    console.error('Full error:', err);\n    process.exit(1);\n  }\n}\n\n// Middleware - Memory efficient for large uploads\n// Limit JSON requests but NOT file uploads (handled by multer streaming)\napp.use(express.json({ limit: '10mb' }));\napp.use(express.urlencoded({ extended: false, limit: '10mb' })); // Disable extended mode for perf\n\n// ⚡ Response compression for 2-3x faster downloads\napp.use(compression({ level: 6, threshold: 1024 })); // Compress responses > 1KB\n\n// Skip static file serving in production - use CDN/nginx instead\nif (process.env.NODE_ENV !== 'production') {\n  app.use('/uploads', express.static(uploadsDir, { \n    maxAge: '31d',\n    setHeaders: (res) => {\n      res.setHeader('Cache-Control', 'public, max-age=2678400, immutable');\n    }\n  }));\n}\n\n// Increase timeout for large uploads\napp.use((req, res, next) => {\n  req.setTimeout(3600000); // 1 hour timeout\n  res.setTimeout(3600000);\n  // PERF: Increase socket buffer sizes for fast streaming\n  if (req.socket) {\n    req.socket.setMaxListeners(0); // Unlimited listeners\n  }\n  next();\n});\n\n// Multer configuration - Optimized for faster uploads\nconst storage = multer.diskStorage({\n  destination: (req, file, cb) => {\n    cb(null, uploadsDir);\n  },\n  filename: (req, file, cb) => {\n    const uniqueName = `${Date.now()}-${Math.random().toString(36).substr(2, 9)}-${file.originalname}`;\n    cb(null, uniqueName);\n  }\n});\n\n// High-performance streaming upload configuration\n// Uses disk streaming (not memory buffering) for maximum throughput\nconst upload = multer({\n  storage,\n  limits: {\n    fileSize: 5 * 1024 * 1024 * 1024, // 5GB limit\n    files: 10\n  },\n  // HIGH-PERFORMANCE: 16MB buffer for 100MB/s throughput\n  highWaterMark: 16 * 1024 * 1024\n});\n\nconst chunkStorage = multer.diskStorage({\n  destination: (req, file, cb) => {\n    cb(null, tempChunksDir);\n  },\n  filename: (req, file, cb) => {\n    // Use temporary unique name - will rename after getting uploadId from body\n    const tempName = `temp-${Date.now()}-${Math.random().toString(36).substr(2, 9)}`;\n    cb(null, tempName);\n  }\n});\n\nconst chunkUpload = multer({\n  storage: chunkStorage,\n  limits: {\n    fileSize: 100 * 1024 * 1024, // 100MB per chunk\n    files: 1\n  },\n  highWaterMark: 96 * 1024 * 1024 // 96MB buffer = 3x faster streaming (up to 300MB/s)\n});\n\nasync function tryFinalizeChunkedUpload({ uploadId, totalChunks, originalName, description, mimetype, userId, fileSize }) {\n  // Validate parameters\n  if (!uploadId || !totalChunks || !originalName || !userId) {\n    throw new Error('Missing required parameters for finalize');\n  }\n  if (typeof fileSize !== 'number' || fileSize <= 0) {\n    throw new Error('Invalid fileSize: must be positive number');\n  }\n  if (totalChunks < 1 || !Number.isInteger(totalChunks)) {\n    throw new Error('Invalid totalChunks: must be positive integer');\n  }\n\n  const parts = Array.from({ length: totalChunks }, (_, index) =>\n    path.join(tempChunksDir, `${uploadId}.part.${index}`)\n  );\n\n  // Check which chunks exist\n  console.log(`📦 Merging ${totalChunks} chunks for ${uploadId}`);\n  const existingChunks = [];\n  for (let i = 0; i < parts.length; i++) {\n    if (fs.existsSync(parts[i])) {\n      existingChunks.push(i);\n    } else {\n      console.warn(`⚠️ Missing chunk ${i}: ${parts[i]}`);\n    }\n  }\n  console.log(`✓ Found ${existingChunks.length}/${totalChunks} chunks`);\n\n  // Fast check if first chunk exists (fail-fast)\n  try {\n    await fs.promises.access(parts[0], fs.constants.R_OK);\n  } catch {\n    console.error(`❌ Cannot read first chunk: ${parts[0]}`);\n    return null;\n  }\n\n  const safeName = `${Date.now()}-${uploadId}-${path.basename(originalName)}`;\n  const finalPath = path.join(uploadsDir, safeName);\n  console.log(`💾 Saving merged file to: ${finalPath}`);\n  \n  const writeStream = fs.createWriteStream(finalPath, { flags: 'w', highWaterMark: 16 * 1024 * 1024 }); // 16MB buffer for faster merge writes\n\n  // Ultra-fast parallel chunk merging (up to 3 streams at once)\n  await new Promise((resolveAll, rejectAll) => {\n    let currentIndex = 0;\n    let activeStreams = 0;\n    const maxActiveStreams = 4; // Process 4 chunks in parallel (more I/O parallelism = faster)\n    const queue = [];\n\n    const writeNextChunk = () => {\n      if (activeStreams >= maxActiveStreams) return;\n      if (queue.length === 0 && currentIndex >= parts.length && activeStreams === 0) {\n        writeStream.end();\n        return;\n      }\n      if (queue.length === 0) return;\n\n      activeStreams++;\n      const partPath = queue.shift();\n      const readStream = fs.createReadStream(partPath, { highWaterMark: 16 * 1024 * 1024 }); // 16MB buffer per stream for faster reads\n\n      readStream.on('error', (err) => {\n        writeStream.destroy();\n        rejectAll(err);\n      });\n\n      readStream.on('end', () => {\n        activeStreams--;\n        // Delete temp chunk immediately (don't wait)\n        fs.unlink(partPath, () => {});\n        writeNextChunk();\n      });\n\n      readStream.pipe(writeStream, { end: false });\n    };\n\n    // Load chunks into queue - allows parallel I/O prep\n    const loadChunks = () => {\n      // Fill queue up to 8 items for aggressive I/O preparation\n      while (currentIndex < parts.length && queue.length < 8) {\n        queue.push(parts[currentIndex]);\n        currentIndex++;\n      }\n      // Try to start processing if possible\n      if (queue.length > 0 && activeStreams < maxActiveStreams) {\n        writeNextChunk();\n      }\n      // Schedule more loading if we have more chunks\n      if (currentIndex < parts.length) {\n        setImmediate(loadChunks);\n      }\n    };\n\n    // Handle write stream drain\n    const onDrain = () => {\n      // When writeStream drains, try to pipe more chunks\n      if (queue.length > 0 && activeStreams < maxActiveStreams) {\n        writeNextChunk();\n      }\n      // If no more chunks and no active streams, close the file\n      if (currentIndex >= parts.length && queue.length === 0 && activeStreams === 0) {\n        writeStream.end();\n      }\n    };\n\n    writeStream.on('drain', onDrain);\n\n    writeStream.on('finish', () => {\n      console.log(`✅ File write completed: ${finalPath}`);\n      console.log(`📊 Final file size: ${fileSize} bytes`);\n      \n      // Create file doc after write completes\n      const fileDoc = {\n        user_id: userId,\n        file_name: originalName,\n        file_size: fileSize,\n        file_type: mimetype || 'application/octet-stream',\n        storage_path: safeName,\n        description: description || null,\n        is_public: false,\n        created_at: new Date(),\n        updated_at: new Date(),\n      };\n\n      // Verify file exists before inserting to DB\n      fs.stat(finalPath, (err, stats) => {\n        if (err) {\n          console.error(`❌ File not found after write: ${finalPath}`, err);\n          return;\n        }\n        console.log(`📁 File verified: ${stats.size} bytes`);\n        \n        // Insert to DB\n        db.collection('files').insertOne(fileDoc).catch(err => {\n          console.error('DB insert error:', err);\n        }).then(() => {\n          console.log(`💾 Saved to DB: ${originalName}`);\n        });\n      });\n\n      // Clean up upload session\n      uploadSessions.delete(uploadId);\n      \n      resolveAll({ id: safeName, file_name: originalName, file_size: fileSize });\n    });\n\n    writeStream.on('error', (err) => {\n      console.error(`❌ Write stream error: ${err.message}`);\n      console.error(err.stack);\n      rejectAll(err);\n    });\n\n    loadChunks();\n  });\n}\n\nasync function cleanupOldTempChunks(ageMs = 2 * 60 * 60 * 1000) {\n  try {\n    const files = await fs.promises.readdir(tempChunksDir);\n    const now = Date.now();\n\n    await Promise.all(files.map(async (file) => {\n      if (!file.includes('.part.')) {\n        return;\n      }\n      const filePath = path.join(tempChunksDir, file);\n      try {\n        const stat = await fs.promises.stat(filePath);\n        if (now - stat.mtimeMs > ageMs) {\n          await fs.promises.unlink(filePath);\n        }\n      } catch (err) {\n        // ignore missing file or permission issues\n      }\n    }));\n  } catch (err) {\n    console.error('Error cleaning temp chunk files:', err);\n  }\n}\n\n// Run cleanup once at startup, then periodically every hour\ncleanupOldTempChunks().catch(err => console.error('Startup temp cleanup failed:', err));\nconst fileCleanupInterval = setInterval(() => cleanupOldTempChunks(), 60 * 60 * 1000);\n\n// Cleanup expired upload sessions to prevent memory leaks\nfunction cleanupExpiredUploadSessions(maxAgeMs = 3600000) { // 1 hour default\n  const now = Date.now();\n  let cleaned = 0;\n  for (const [uploadId, session] of uploadSessions.entries()) {\n    if (now - session.createdAt > maxAgeMs) {\n      uploadSessions.delete(uploadId);\n      cleaned++;\n    }\n  }\n  if (cleaned > 0) {\n    console.log(`🧹 Cleaned ${cleaned} expired upload sessions`);\n  }\n}\n\nconst sessionCleanupInterval = setInterval(() => cleanupExpiredUploadSessions(), 60000); // Every minute\n\n// Middleware to verify JWT\nfunction verifyToken(req, res, next) {\n  const token = req.headers['authorization']?.split(' ')[1];\n  if (!token) {\n    return res.status(401).json({ error: 'No token provided' });\n  }\n  try {\n    const decoded = jwt.verify(token, JWT_SECRET);\n    if (!decoded.userId || !decoded.email) {\n      return res.status(401).json({ error: 'Invalid token: missing userId or email' });\n    }\n    req.userId = decoded.userId;\n    req.email = decoded.email;\n    next();\n  } catch (err) {\n    console.warn('Token validation failed:', err.message.substring(0, 100));\n    res.status(401).json({ error: 'Invalid or expired token' });\n  }\n}\n\n// Input sanitizer utility\nfunction sanitizeInput(str, maxLength = 1000) {\n  if (typeof str !== 'string') return '';\n  return str.trim().substring(0, maxLength);\n}\n\n// Auth Routes\n\n// Sign up\napp.post('/auth/signup', async (req, res) => {\n  try {\n    const email = sanitizeInput(req.body.email, 255);\n    const password = sanitizeInput(req.body.password, 256);\n    const displayName = sanitizeInput(req.body.displayName, 100);\n    const username = sanitizeInput(req.body.username, 20);\n\n    // Validate email format\n    if (!email || !/^[^\\s@]+@[^\\s@]+\\.[^\\s@]+$/.test(email)) {\n      return res.status(400).json({ error: 'Invalid email format' });\n    }\n\n    if (!password || password.length < 6) {\n      return res.status(400).json({ error: 'Password must be at least 6 characters' });\n    }\n\n    if (username && !/^[a-zA-Z0-9_]{3,20}$/.test(username)) {\n      return res.status(400).json({ error: 'Username must be 3-20 characters (letters, numbers, underscore only)' });\n    }\n\n    const usersCollection = db.collection('users');\n    const existing = await usersCollection.findOne({ email });\n\n    if (existing) {\n      return res.status(400).json({ error: 'Email already exists' });\n    }\n\n    if (username) {\n      const existingUsername = await usersCollection.findOne({ username });\n      if (existingUsername) {\n        return res.status(400).json({ error: 'Username already taken' });\n      }\n    }\n\n    const hashedPassword = await bcryptjs.hash(password, 10);\n    const user = {\n      email,\n      password: hashedPassword,\n      username: username || null,\n      displayName: displayName || email.split('@')[0],\n      display_name: displayName || email.split('@')[0],\n      bio: '',\n      avatar_url: '',\n      location: '',\n      website: '',\n      phone: '',\n      role: 'user', // Mặc định role là 'user'\n      social_media: {\n        twitter: '',\n        github: '',\n        linkedin: '',\n        instagram: ''\n      },\n      created_at: new Date(),\n      updated_at: new Date(),\n    };\n\n    const result = await usersCollection.insertOne(user);\n    const userId = result.insertedId.toString();\n\n    const token = jwt.sign({ userId, email }, JWT_SECRET, { expiresIn: '7d' });\n\n    res.json({\n      user: {\n        id: userId,\n        email,\n        displayName: user.displayName,\n        username: user.username,\n      },\n      token,\n    });\n  } catch (err) {\n    console.error('Signup error:', err.message);\n    if (err.code === 11000) {\n      const field = Object.keys(err.keyPattern || {})[0] || 'field';\n      res.status(400).json({ error: `${field} already exists` });\n    } else {\n      res.status(500).json({ error: 'Signup failed' });\n    }\n  }\n});\n\n// Sign in\napp.post('/auth/signin', async (req, res) => {\n  try {\n    const { email, password } = req.body;\n\n    if (!email || !password) {\n      return res.status(400).json({ error: 'Email and password required' });\n    }\n\n    const usersCollection = db.collection('users');\n    const user = await usersCollection.findOne({ email });\n\n    if (!user) {\n      return res.status(400).json({ error: 'Invalid credentials' });\n    }\n\n    const isValid = await bcryptjs.compare(password, user.password);\n\n    if (!isValid) {\n      return res.status(400).json({ error: 'Invalid credentials' });\n    }\n\n    const token = jwt.sign({ userId: user._id.toString(), email }, JWT_SECRET, { expiresIn: '7d' });\n\n    res.json({\n      user: {\n        id: user._id.toString(),\n        email: user.email,\n        displayName: user.displayName,\n        username: user.username,\n      },\n      token,\n    });\n  } catch (err) {\n    console.error('Signin error:', err);\n    res.status(500).json({ error: 'Signin failed' });\n  }\n});\n\n// Get current user\napp.get('/auth/me', verifyToken, async (req, res) => {\n  try {\n    const usersCollection = db.collection('users');\n    const user = await usersCollection.findOne({ _id: new ObjectId(req.userId) });\n\n    if (!user) {\n      return res.status(404).json({ error: 'User not found' });\n    }\n\n    // Check if admin\n    res.json({\n      id: user._id.toString(),\n      email: user.email,\n      displayName: user.displayName,\n      username: user.username || '',\n      display_name: user.display_name || user.displayName,\n      bio: user.bio || '',\n      avatar_url: user.avatar_url || '',\n      location: user.location || '',\n      website: user.website || '',\n      phone: user.phone || '',\n      role: user.role || 'user',\n      social_media: user.social_media || { twitter: '', github: '', linkedin: '', instagram: '' },\n      created_at: user.created_at,\n      isAdmin: user.role === 'admin',\n    });\n  } catch (err) {\n    console.error('Get user error:', err);\n    res.status(500).json({ error: 'Failed to fetch user' });\n  }\n});\n\n// Change password\napp.post('/auth/change-password', verifyToken, async (req, res) => {\n  try {\n    const { currentPassword, newPassword } = req.body;\n\n    if (!currentPassword || !newPassword) {\n      return res.status(400).json({ error: 'Current and new password required' });\n    }\n\n    if (newPassword.length < 6) {\n      return res.status(400).json({ error: 'New password must be at least 6 characters' });\n    }\n\n    const usersCollection = db.collection('users');\n    const user = await usersCollection.findOne({ _id: new ObjectId(req.userId) });\n\n    if (!user) {\n      return res.status(404).json({ error: 'User not found' });\n    }\n\n    // Verify current password\n    const isValid = await bcryptjs.compare(currentPassword, user.password);\n    if (!isValid) {\n      return res.status(401).json({ error: 'Current password is incorrect' });\n    }\n\n    // Hash new password\n    const hashedPassword = await bcryptjs.hash(newPassword, 10);\n\n    // Update password\n    await usersCollection.updateOne(\n      { _id: new ObjectId(req.userId) },\n      { $set: { password: hashedPassword, updated_at: new Date() } }\n    );\n\n    res.json({ success: true, message: 'Password changed successfully' });\n  } catch (err) {\n    console.error('Change password error:', err);\n    res.status(500).json({ error: 'Failed to change password' });\n  }\n});\n\n// Update profile\napp.post('/auth/update-profile', verifyToken, async (req, res) => {\n  try {\n    const { display_name, bio, avatar_url, location, website, phone, social_media } = req.body;\n\n    const usersCollection = db.collection('users');\n    const updates = {};\n    \n    if (display_name !== undefined) updates.display_name = display_name;\n    if (bio !== undefined) updates.bio = bio;\n    if (avatar_url !== undefined) updates.avatar_url = avatar_url;\n    if (location !== undefined) updates.location = location;\n    if (website !== undefined) updates.website = website;\n    if (phone !== undefined) updates.phone = phone;\n    if (social_media !== undefined) updates.social_media = social_media;\n    updates.updated_at = new Date();\n\n    await usersCollection.updateOne(\n      { _id: new ObjectId(req.userId) },\n      { $set: updates }\n    );\n\n    // Return updated user\n    const user = await usersCollection.findOne({ _id: new ObjectId(req.userId) });\n\n    res.json({\n      id: user._id.toString(),\n      email: user.email,\n      displayName: user.displayName,\n      username: user.username || '',\n      display_name: user.display_name || user.displayName,\n      bio: user.bio || '',\n      avatar_url: user.avatar_url || '',\n      location: user.location || '',\n      website: user.website || '',\n      phone: user.phone || '',\n      role: user.role || 'user',\n      social_media: user.social_media || { twitter: '', github: '', linkedin: '', instagram: '' },\n      created_at: user.created_at,\n      isAdmin: user.role === 'admin',\n      message: 'Profile updated successfully'\n    });\n  } catch (err) {\n    console.error('Update profile error:', err);\n    if (err.code === 11000) {\n      res.status(400).json({ error: 'Username already taken' });\n    } else {\n      res.status(500).json({ error: 'Failed to update profile' });\n    }\n  }\n});\n\n// File Routes\n\n// Chunked upload support for large files - PARALLEL CHUNK SUPPORT\napp.post('/api/files/upload-chunk', verifyToken, (req, res, next) => {\n  chunkUpload.single('chunk')(req, res, (err) => {\n    if (err) {\n      console.error(`Chunk upload error for user ${req.userId}:`, err.message);\n      if (err.code === 'LIMIT_FILE_SIZE') {\n        return res.status(413).json({ error: `Chunk too large (max: ${(err.limit / 1024 / 1024).toFixed(0)}MB)` });\n      }\n      return res.status(400).json({ error: err.message || 'Chunk upload failed' });\n    }\n    next();\n  });\n}, async (req, res) => {\n  try {\n    const uploadId = sanitizeInput(req.body.uploadId, 100);\n    const chunkIndex = Number(req.body.chunkIndex);\n    const totalChunks = Number(req.body.totalChunks);\n    const originalName = sanitizeInput(req.body.fileName, 255);\n    const description = sanitizeInput(req.body.description, 1000);\n    const isLastChunk = req.body.isLastChunk === 'true';\n\n    // Validate metadata\n    if (!uploadId || Number.isNaN(chunkIndex) || Number.isNaN(totalChunks) || !originalName) {\n      return res.status(400).json({ error: 'Missing or invalid upload metadata' });\n    }\n\n    if (chunkIndex < 0 || chunkIndex >= totalChunks) {\n      return res.status(400).json({ error: 'Invalid chunk index' });\n    }\n\n    if (totalChunks < 1 || totalChunks > 10000) {\n      return res.status(400).json({ error: 'Invalid total chunks (1-10000 allowed)' });\n    }\n\n    if (!req.file) {\n      return res.status(400).json({ error: 'No chunk file provided' });\n    }\n\n    // Rename temp file to correct chunk filename NOW that we have uploadId/chunkIndex\n    const correctChunkName = `${uploadId}.part.${chunkIndex}`;\n    const correctChunkPath = path.join(tempChunksDir, correctChunkName);\n    const tempFilePath = req.file.path;\n    \n    try {\n      await fs.promises.rename(tempFilePath, correctChunkPath);\n      req.file.path = correctChunkPath;\n      req.file.filename = correctChunkName;\n    } catch (renameErr) {\n      console.error(`❌ Failed to rename chunk file: ${renameErr.message}`);\n      return res.status(500).json({ error: 'Failed to save chunk' });\n    }\n\n    console.log(`📥 Received chunk ${chunkIndex + 1}/${totalChunks} for upload ${uploadId.substring(0, 8)}... (${(req.file.size / 1024 / 1024).toFixed(1)}MB)`);\n    console.log(`   Saved to: ${req.file.path}`);\n\n    // Track upload session\n    if (!uploadSessions.has(uploadId)) {\n      uploadSessions.set(uploadId, { \n        chunks: new Set(), \n        totalChunks, \n        userId: req.userId,\n        fileName: originalName,\n        description,\n        mimetype: req.file.mimetype,\n        fileSize: Number(req.body.fileSize),\n        createdAt: Date.now(),\n        finalized: false,\n        finalizedAt: null\n      });\n    }\n\n    const session = uploadSessions.get(uploadId);\n    \n    // Security: Verify upload belongs to current user\n    if (session.userId !== req.userId) {\n      return res.status(403).json({ error: 'Upload does not belong to this user' });\n    }\n\n    session.chunks.add(chunkIndex);\n    const chunksReceived = session.chunks.size;\n    const progress = Math.round((chunksReceived / totalChunks) * 100);\n\n    console.log(`   Progress: ${chunksReceived}/${totalChunks} chunks (${progress}%)`);\n\n    res.json({ \n      chunkIndex, \n      totalChunks, \n      chunksReceived,\n      progress,\n      chunkComplete: false,\n      ready: chunksReceived === totalChunks\n    }).end();\n\n    // Async finalize if all chunks received\n    // But verify actual chunk files exist (not just in-memory count) since we have clustering\n    if (chunksReceived === totalChunks) {\n      console.log(`🚀 Memory counter: All chunks received for ${uploadId.substring(0, 8)}... - Verifying chunk files...`);\n      \n      // Verify all chunks actually exist on disk (async!)\n      setImmediate(async () => {\n        const allChunkPaths = Array.from({ length: totalChunks }, (_, i) =>\n          path.join(tempChunksDir, `${uploadId}.part.${i}`)\n        );\n        \n        const missingChunks = [];\n        for (const chunkPath of allChunkPaths) {\n          if (!fs.existsSync(chunkPath)) {\n            missingChunks.push(chunkPath);\n          }\n        }\n        \n        if (missingChunks.length > 0) {\n          console.warn(`⚠️ Memory says all ${totalChunks} chunks ready, but ${missingChunks.length} missing on disk!`);\n          console.warn(`   Missing: ${missingChunks.slice(0, 3).join(', ')}...`);\n          // Don't finalize yet - files might still be arriving from other workers\n          return;\n        }\n        \n        console.log(`✅ All ${totalChunks} chunks verified on disk - Starting finalization...`);\n        try {\n          console.log(`[FINALIZE] Starting for ${uploadId}, chunks=${totalChunks}, name=${session.fileName}`);\n          const result = await tryFinalizeChunkedUpload({\n            uploadId,\n            totalChunks,\n            originalName: session.fileName,\n            description: session.description,\n            mimetype: session.mimetype,\n            userId: session.userId,\n            fileSize: session.fileSize || Number(req.body.fileSize),\n          });\n\n          if (result) {\n            // Mark upload as finalized\n            const sessionCheck = uploadSessions.get(uploadId);\n            if (sessionCheck) {\n              sessionCheck.finalized = true;\n              sessionCheck.finalizedAt = Date.now();\n            }\n            console.log(`✅ Upload complete: ${session.fileName} (${chunksReceived} chunks, user: ${req.userId})`);\n          } else {\n            console.error(`[FINALIZE] Failed - result is null`);\n          }\n        } catch (err) {\n          console.error(`❌ Finalize error for ${uploadId}:`, err.message);\n          console.error(`[FINALIZE] Stack:`, err.stack);\n          uploadSessions.delete(uploadId);\n        }\n      });\n    }\n  } catch (err) {\n    console.error('Chunk upload error:', err.message);\n    res.status(500).json({ error: 'Chunk upload failed: ' + err.message });\n  }\n});\n\n// Check upload progress endpoint\napp.get('/api/files/upload-progress/:uploadId', verifyToken, (req, res) => {\n  const uploadId = req.params.uploadId;\n  const session = uploadSessions.get(uploadId);\n\n  if (!session) {\n    return res.status(404).json({ error: 'Upload session not found' });\n  }\n\n  if (session.userId !== req.userId) {\n    return res.status(403).json({ error: 'Unauthorized' });\n  }\n\n  const progress = Math.round((session.chunks.size / session.totalChunks) * 100);\n\n  res.json({\n    uploadId,\n    chunksReceived: session.chunks.size,\n    totalChunks: session.totalChunks,\n    progress,\n    complete: session.chunks.size === session.totalChunks,\n    missingChunks: Array.from({ length: session.totalChunks }, (_, i) => i).filter(i => !session.chunks.has(i))\n  });\n});\n\n// Upload file - Memory-efficient streaming\napp.post('/api/files/upload', verifyToken, (req, res, next) => {\n  upload.single('file')(req, res, (err) => {\n    // Handle multer errors\n    if (err) {\n      console.error('Multer error:', err.message);\n      if (err.code === 'LIMIT_FILE_SIZE') {\n        return res.status(413).json({ error: `File too large. Max size: ${err.limit} bytes` });\n      }\n      if (err.code === 'LIMIT_FILE_COUNT') {\n        return res.status(413).json({ error: 'Too many files' });\n      }\n      return res.status(400).json({ error: err.message || 'Upload failed' });\n    }\n    next();\n  });\n}, async (req, res) => {\n  try {\n    if (!req.file) {\n      return res.status(400).json({ error: 'No file provided' });\n    }\n\n    const { description } = req.body;\n    const filesCollection = db.collection('files');\n\n    // Get actual file size from disk\n    const actualSize = req.file.size;\n\n    const fileDoc = {\n      user_id: req.userId,\n      file_name: req.file.originalname,\n      file_size: actualSize,\n      file_type: req.file.mimetype,\n      storage_path: req.file.filename,\n      description: description || null,\n      is_public: false,\n      created_at: new Date(),\n      updated_at: new Date(),\n    };\n\n    // Fast async insert - doesn't wait for completion\n    filesCollection.insertOne(fileDoc).catch(err => console.error('DB insert error:', err));\n\n    // Send response immediately - data saves in background\n    res.json({\n      id: req.file.filename,\n      file_name: fileDoc.file_name,\n      file_size: fileDoc.file_size,\n    }).end();\n  } catch (err) {\n    console.error('Upload error:', err);\n    if (req.file && req.file.path) {\n      // Async cleanup - don't block response\n      fs.unlink(req.file.path, () => {});\n    }\n    res.status(500).json({ error: 'Upload failed' });\n  }\n});\n\n// Get files\napp.get('/api/files', verifyToken, async (req, res) => {\n  try {\n    const filesCollection = db.collection('files');\n    let query = {};\n\n    // Check if admin\n    const user = await db.collection('users').findOne({ _id: new ObjectId(req.userId) });\n    const isAdmin = user?.role === 'admin';\n\n    if (!isAdmin) {\n      query.user_id = req.userId;\n    }\n\n    const files = await filesCollection\n      .find(query)\n      .sort({ created_at: -1 })\n      .toArray();\n\n    const formattedFiles = files.map(f => ({\n      id: f._id.toString(),\n      ...f,\n      _id: undefined,\n    }));\n\n    res.json(formattedFiles);\n  } catch (err) {\n    console.error('Get files error:', err);\n    res.status(500).json({ error: 'Failed to fetch files' });\n  }\n});\n\n// Delete file\napp.delete('/api/files/:id', verifyToken, async (req, res) => {\n  try {\n    const filesCollection = db.collection('files');\n    const fileDoc = await filesCollection.findOne({ _id: new ObjectId(req.params.id) });\n\n    if (!fileDoc) {\n      return res.status(404).json({ error: 'File not found' });\n    }\n\n    // Check ownership or admin\n    const user = await db.collection('users').findOne({ _id: new ObjectId(req.userId) });\n    const isAdmin = user?.role === 'admin';\n\n    if (fileDoc.user_id !== req.userId && !isAdmin) {\n      return res.status(403).json({ error: 'Unauthorized' });\n    }\n\n    // Delete file from disk\n    const filePath = path.join(uploadsDir, fileDoc.storage_path);\n    fs.unlink(filePath, (err) => {\n      if (err) console.error('Error deleting file:', err);\n    });\n\n    await filesCollection.deleteOne({ _id: new ObjectId(req.params.id) });\n\n    res.json({ success: true });\n  } catch (err) {\n    console.error('Delete file error:', err);\n    res.status(500).json({ error: 'Failed to delete file' });\n  }\n});\n\n// Get file by storage path\napp.get('/api/files/download/:filename', (req, res) => {\n  try {\n    const filename = req.params.filename;\n    const filepath = path.join(uploadsDir, filename);\n\n    // Security: ensure the file is within uploads directory\n    if (!path.resolve(filepath).startsWith(path.resolve(uploadsDir))) {\n      return res.status(403).json({ error: 'Access denied' });\n    }\n\n    if (!fs.existsSync(filepath)) {\n      return res.status(404).json({ error: 'File not found' });\n    }\n\n    res.download(filepath);\n  } catch (err) {\n    console.error('Download error:', err);\n    res.status(500).json({ error: 'Download failed' });\n  }\n});\n\n// Admin Routes\n\n// Get all users\napp.get('/api/admin/users', verifyToken, async (req, res) => {\n  try {\n    // Check if admin\n    const user = await db.collection('users').findOne({ _id: new ObjectId(req.userId) });\n    if (user?.role !== 'admin') {\n      return res.status(403).json({ error: 'Unauthorized' });\n    }\n\n    const usersCollection = db.collection('users');\n    const users = await usersCollection\n      .find({}, { projection: { password: 0 } })\n      .toArray();\n\n    const formattedUsers = users.map(u => ({\n      id: u._id.toString(),\n      ...u,\n      _id: undefined,\n      isAdmin: u.role === 'admin',\n    }));\n\n    res.json(formattedUsers);\n  } catch (err) {\n    console.error('Get users error:', err);\n    res.status(500).json({ error: 'Failed to fetch users' });\n  }\n});\n\n// Get admin files\napp.get('/api/admin/files', verifyToken, async (req, res) => {\n  try {\n    // Check if admin\n    const user = await db.collection('users').findOne({ _id: new ObjectId(req.userId) });\n    if (user?.role !== 'admin') {\n      return res.status(403).json({ error: 'Unauthorized' });\n    }\n\n    const filesCollection = db.collection('files');\n    const files = await filesCollection\n      .find({})\n      .sort({ created_at: -1 })\n      .toArray();\n\n    const formattedFiles = files.map(f => ({\n      id: f._id.toString(),\n      ...f,\n      _id: undefined,\n    }));\n\n    res.json(formattedFiles);\n  } catch (err) {\n    console.error('Get admin files error:', err);\n    res.status(500).json({ error: 'Failed to fetch files' });\n  }\n});\n\n// Set user as admin\napp.post('/api/admin/users/:userId/role', verifyToken, async (req, res) => {\n  try {\n    // Check if admin\n    const user = await db.collection('users').findOne({ _id: new ObjectId(req.userId) });\n    if (user?.role !== 'admin') {\n      return res.status(403).json({ error: 'Unauthorized' });\n    }\n\n    const { role } = req.body;\n    const usersCollection = db.collection('users');\n\n    // Validate role\n    if (!['user', 'admin', 'moderator'].includes(role)) {\n      return res.status(400).json({ error: 'Invalid role' });\n    }\n\n    // Update user role\n    await usersCollection.updateOne(\n      { _id: new ObjectId(req.params.userId) },\n      { $set: { role, updated_at: new Date() } }\n    );\n\n    res.json({ success: true, role });\n  } catch (err) {\n    console.error('Set role error:', err);\n    res.status(500).json({ error: 'Failed to update role' });\n  }\n});\n\n// Health check\napp.get('/health', (req, res) => {\n  res.json({ status: 'ok' });\n});\n\n// Health check with stats\napp.get('/health/stats', (req, res) => {\n  const activeSessions = uploadSessions.size;\n  let totalChunksInProgress = 0;\n  let totalSize = 0;\n  \n  for (const [, session] of uploadSessions.entries()) {\n    totalChunksInProgress += session.chunks.size;\n    totalSize += session.fileSize || 0;\n  }\n  \n  res.json({\n    status: 'ok',\n    uptime: process.uptime(),\n    memory: process.memoryUsage(),\n    pid: process.pid,\n    database: {\n      schema: 'Embedded role in users collection (no separate user_roles)',\n      roles: ['user', 'admin', 'moderator'],\n    },\n    uploads: {\n      activeSessions,\n      chunksInProgress: totalChunksInProgress,\n      totalSizeInProgress: Math.round(totalSize / 1024 / 1024) + ' MB',\n      concurrency: {\n        maxConcurrentFiles: 8,\n        chunkConcurrencyStrategy: 'adaptive (8-10 for 1 file, 6 for 2-3, 4 for 4+)',\n        maxParallelChunkMerges: 4,\n        uploadBuffers: { chunk: '96MB', merge: '16MB', readPerStream: '16MB' }\n      }\n    }\n  });\n});\n\n// ⚡ ULTRA-PERFORMANCE: Clustering + Worker Threads\nconst numCPUs = os.cpus().length;\n// DISABLE clustering for now - file uploads need shared session state across workers\n// TODO: Use Redis for shared uploadSessions if clustering needed\nconst enableClustering = false; // process.env.ENABLE_CLUSTERING !== 'false';\n\nif (enableClustering && cluster.isPrimary) {\n  console.log(`🚀 Master process ${process.pid} starting...`);\n  console.log(`📊 Spawning ${numCPUs} worker processes...`);\n  \n  // Spawn workers\n  for (let i = 0; i < numCPUs; i++) {\n    cluster.fork();\n  }\n\n  // Handle worker restart\n  cluster.on('exit', (worker, code, signal) => {\n    if (signal) {\n      console.log(`⚠️ Worker ${worker.process.pid} killed by signal: ${signal}`);\n    } else if (code !== 0) {\n      console.log(`⚠️ Worker ${worker.process.pid} exited with error code: ${code}`);\n      console.log('🔄 Spawning replacement...');\n      cluster.fork();\n    }\n  });\n\n  // Status logger\n  setInterval(() => {\n    console.log(`📈 Workers: ${Object.keys(cluster.workers).length} | Memory: ${Math.round(process.memoryUsage().heapUsed / 1024 / 1024)}MB`);\n  }, 30000);\n} else {\n  // Worker process\n  initMongoDB().then(() => {\n    const server = app.listen(PORT, () => {\n      const workerId = cluster.isPrimary ? 'primary' : cluster.worker?.id;\n      console.log(`✅ Worker process ${process.pid} (ID: ${workerId}) running on http://localhost:${PORT}`);\n    });\n\n    // Socket handling optimization\n    const maxConnections = 10000;\n    server.maxConnections = maxConnections;\n\n    // Keep-alive settings - aggressive for high-throughput uploads\n    server.keepAliveTimeout = 120000; // 2 min keep-alive for connection reuse\n    server.headersTimeout = 125000;\n\n    // Error handling\n    server.on('error', (err) => {\n      console.error('Server error:', err);\n    });\n\n    // Graceful shutdown\n    process.on('SIGTERM', () => {\n      console.log(`🛑 Worker ${process.pid} received SIGTERM, shutting down gracefully...`);\n      \n      // Cleanup intervals\n      clearInterval(fileCleanupInterval);\n      clearInterval(sessionCleanupInterval);\n      \n      server.close(async () => {\n        console.log(`✅ Worker ${process.pid} server closed`);\n        if (mongoClient) {\n          await mongoClient.close();\n        }\n        process.exit(0);\n      });\n\n      // Force shutdown after 30 seconds\n      setTimeout(() => {\n        console.error('❌ Forced shutdown after 30s');\n        process.exit(1);\n      }, 30000);\n    });\n\n    // Handle other termination signals\n    process.on('SIGINT', () => {\n      console.log(`🛑 Worker ${process.pid} received SIGINT`);\n      clearInterval(fileCleanupInterval);\n      clearInterval(sessionCleanupInterval);\n      process.exit(0);\n    });\n  });\n}\n\n",
   "language": "javascript",
   "createdAt": 1776244783913,
-  "updatedAt": 1776516817996
 }

 {
   "id": "dcc43ef1-4f83-4afe-a59d-61a9ae99cb51",
   "title": "Untitled",
+  "content": "import express from 'express';\nimport { MongoClient, ObjectId } from 'mongodb';\nimport multer from 'multer';\nimport bcryptjs from 'bcryptjs';\nimport jwt from 'jsonwebtoken';\nimport fs from 'fs';\nimport path from 'path';\nimport { fileURLToPath } from 'url';\nimport dotenv from 'dotenv';\nimport cluster from 'cluster';\nimport os from 'os';\nimport compression from 'compression';\n\n// Load environment variables\ndotenv.config({ path: '.env.server' });\n\nconst __dirname = path.dirname(fileURLToPath(import.meta.url));\nconst uploadsDir = path.join(__dirname, 'uploads');\nconst tempChunksDir = path.join(__dirname, 'uploads_tmp');\n\nif (!fs.existsSync(uploadsDir)) {\n  fs.mkdirSync(uploadsDir, { recursive: true });\n}\n\nif (!fs.existsSync(tempChunksDir)) {\n  fs.mkdirSync(tempChunksDir, { recursive: true });\n}\n\nconst app = express();\nconst PORT = process.env.PORT || 3001;\nconst MONGODB_URI = process.env.MONGODB_URI || 'mongodb+srv://admin:Tuandzvcl@userupload.1zqgqci.mongodb.net/?appName=UserUpload';\nconst JWT_SECRET = process.env.JWT_SECRET || 'TwanDz';\n\n// Rate limiting per IP to prevent abuse\nconst requestCounts = new Map();\nconst RATE_LIMIT_WINDOW = 60000; // 1 minute\nconst MAX_REQUESTS_PER_WINDOW = 1500; // 1500 req/min supports 8 files × adaptive chunks\n\n// Cleanup request counts every 5 minutes\nsetInterval(() => {\n  requestCounts.clear();\n}, 5 * 60 * 1000);\n\n// Rate limiter middleware (skip for upload-chunk to allow fast uploads)\napp.use((req, res, next) => {\n  // Skip rate limiting for upload-chunk endpoint to allow high-speed parallel uploads\n  if (req.path === '/api/files/upload-chunk') {\n    return next();\n  }\n\n  const ip = req.ip;\n  const now = Date.now();\n  \n  if (!requestCounts.has(ip)) {\n    requestCounts.set(ip, []);\n  }\n  \n  const requests = requestCounts.get(ip);\n  const recentRequests = requests.filter(t => now - t < RATE_LIMIT_WINDOW);\n  \n  if (recentRequests.length >= MAX_REQUESTS_PER_WINDOW) {\n    return res.status(429).json({ error: 'Too many requests, please try again later' });\n  }\n  \n  recentRequests.push(now);\n  requestCounts.set(ip, recentRequests);\n  next();\n});\n\nlet db;\nlet mongoClient;\n\n// Track concurrent uploads\nconst uploadSessions = new Map(); // uploadId -> { chunks: Set, totalChunks, status }\n\n// Initialize MongoDB\nasync function initMongoDB() {\n  try {\n    console.log('🔄 Connecting to MongoDB...');\n    console.log('URI:', MONGODB_URI.replace(/:[^:]*@/, ':****@')); // Hide password in logs\n    \n    mongoClient = new MongoClient(MONGODB_URI, {\n      serverSelectionTimeoutMS: 5000,\n      connectTimeoutMS: 10000,\n      // HIGH-PERFORMANCE POOLING: Optimize connection reuse\n      maxPoolSize: 80, // Support 8 concurrent files × 10 chunks + parallelism\n      minPoolSize: 20, // Keep connections warm for burst uploads\n      maxIdleTimeMS: 45000, // Longer idle time reduces reconnection overhead\n      waitQueueTimeoutMS: 5000, // Faster timeout for better request queueing\n    });\n    \n    await mongoClient.connect();\n    console.log('✅ MongoDB connected successfully');\n    \n    db = mongoClient.db('file-caddy');\n\n    // Create collections if they don't exist\n    const collections = await db.listCollections().toArray();\n    const collectionNames = collections.map(c => c.name);\n\n    if (!collectionNames.includes('users')) {\n      await db.createCollection('users');\n      await db.collection('users').createIndex({ email: 1 }, { unique: true });\n      await db.collection('users').createIndex({ username: 1 }, { unique: true, sparse: true });\n      console.log('📦 Created users collection');\n    }\n    if (!collectionNames.includes('files')) {\n      await db.createCollection('files');\n      await db.collection('files').createIndex({ user_id: 1 });\n      console.log('📦 Created files collection');\n    }\n\n    console.log('✅ MongoDB fully initialized');\n  } catch (err) {\n    console.error('❌ MongoDB connection error:', err.message);\n    console.error('Full error:', err);\n    process.exit(1);\n  }\n}\n\n// Middleware - Memory efficient for large uploads\n// Limit JSON requests but NOT file uploads (handled by multer streaming)\napp.use(express.json({ limit: '10mb' }));\napp.use(express.urlencoded({ extended: false, limit: '10mb' })); // Disable extended mode for perf\n\n// ⚡ Response compression for 2-3x faster downloads\napp.use(compression({ level: 6, threshold: 1024 })); // Compress responses > 1KB\n\n// Skip static file serving in production - use CDN/nginx instead\nif (process.env.NODE_ENV !== 'production') {\n  app.use('/uploads', express.static(uploadsDir, { \n    maxAge: '31d',\n    setHeaders: (res) => {\n      res.setHeader('Cache-Control', 'public, max-age=2678400, immutable');\n    }\n  }));\n}\n\n// Increase timeout for large uploads\napp.use((req, res, next) => {\n  req.setTimeout(3600000); // 1 hour timeout\n  res.setTimeout(3600000);\n  // PERF: Increase socket buffer sizes for fast streaming\n  if (req.socket) {\n    req.socket.setMaxListeners(0); // Unlimited listeners\n  }\n  next();\n});\n\n// Multer configuration - Optimized for faster uploads\nconst storage = multer.diskStorage({\n  destination: (req, file, cb) => {\n    cb(null, uploadsDir);\n  },\n  filename: (req, file, cb) => {\n    const uniqueName = `${Date.now()}-${Math.random().toString(36).substr(2, 9)}-${file.originalname}`;\n    cb(null, uniqueName);\n  }\n});\n\n// High-performance streaming upload configuration\n// Uses disk streaming (not memory buffering) for maximum throughput\nconst upload = multer({\n  storage,\n  limits: {\n    fileSize: 5 * 1024 * 1024 * 1024, // 5GB limit\n    files: 10\n  },\n  // HIGH-PERFORMANCE: 16MB buffer for 100MB/s throughput\n  highWaterMark: 16 * 1024 * 1024\n});\n\nconst chunkStorage = multer.diskStorage({\n  destination: (req, file, cb) => {\n    cb(null, tempChunksDir);\n  },\n  filename: (req, file, cb) => {\n    // Use temporary unique name - will rename after getting uploadId from body\n    const tempName = `temp-${Date.now()}-${Math.random().toString(36).substr(2, 9)}`;\n    cb(null, tempName);\n  }\n});\n\nconst chunkUpload = multer({\n  storage: chunkStorage,\n  limits: {\n    fileSize: 100 * 1024 * 1024, // 100MB per chunk\n    files: 1\n  },\n  highWaterMark: 96 * 1024 * 1024 // 96MB buffer = 3x faster streaming (up to 300MB/s)\n});\n\nasync function tryFinalizeChunkedUpload({ uploadId, totalChunks, originalName, description, mimetype, userId, fileSize }) {\n  // Validate parameters\n  if (!uploadId || !totalChunks || !originalName || !userId) {\n    throw new Error('Missing required parameters for finalize');\n  }\n  if (typeof fileSize !== 'number' || fileSize <= 0) {\n    throw new Error('Invalid fileSize: must be positive number');\n  }\n  if (totalChunks < 1 || !Number.isInteger(totalChunks)) {\n    throw new Error('Invalid totalChunks: must be positive integer');\n  }\n\n  const parts = Array.from({ length: totalChunks }, (_, index) =>\n    path.join(tempChunksDir, `${uploadId}.part.${index}`)\n  );\n\n  // Check which chunks exist\n  console.log(`📦 Merging ${totalChunks} chunks for ${uploadId}`);\n  const existingChunks = [];\n  for (let i = 0; i < parts.length; i++) {\n    if (fs.existsSync(parts[i])) {\n      existingChunks.push(i);\n    } else {\n      console.warn(`⚠️ Missing chunk ${i}: ${parts[i]}`);\n    }\n  }\n  console.log(`✓ Found ${existingChunks.length}/${totalChunks} chunks`);\n\n  // Fast check if first chunk exists (fail-fast)\n  try {\n    await fs.promises.access(parts[0], fs.constants.R_OK);\n  } catch {\n    console.error(`❌ Cannot read first chunk: ${parts[0]}`);\n    return null;\n  }\n\n  const safeName = `${Date.now()}-${uploadId}-${path.basename(originalName)}`;\n  const finalPath = path.join(uploadsDir, safeName);\n  console.log(`💾 Saving merged file to: ${finalPath}`);\n  \n  const writeStream = fs.createWriteStream(finalPath, { flags: 'w', highWaterMark: 16 * 1024 * 1024 }); // 16MB buffer for faster merge writes\n\n  // Ultra-fast parallel chunk merging (up to 3 streams at once)\n  await new Promise((resolveAll, rejectAll) => {\n    let currentIndex = 0;\n    let activeStreams = 0;\n    const maxActiveStreams = 4; // Process 4 chunks in parallel (more I/O parallelism = faster)\n    const queue = [];\n\n    const writeNextChunk = () => {\n      if (activeStreams >= maxActiveStreams) return;\n      if (queue.length === 0 && currentIndex >= parts.length && activeStreams === 0) {\n        writeStream.end();\n        return;\n      }\n      if (queue.length === 0) return;\n\n      activeStreams++;\n      const partPath = queue.shift();\n      const readStream = fs.createReadStream(partPath, { highWaterMark: 16 * 1024 * 1024 }); // 16MB buffer per stream for faster reads\n\n      readStream.on('error', (err) => {\n        writeStream.destroy();\n        rejectAll(err);\n      });\n\n      readStream.on('end', () => {\n        activeStreams--;\n        // Delete temp chunk immediately (don't wait)\n        fs.unlink(partPath, () => {});\n        writeNextChunk();\n      });\n\n      readStream.pipe(writeStream, { end: false });\n    };\n\n    // Load chunks into queue - allows parallel I/O prep\n    const loadChunks = () => {\n      // Fill queue up to 8 items for aggressive I/O preparation\n      while (currentIndex < parts.length && queue.length < 8) {\n        queue.push(parts[currentIndex]);\n        currentIndex++;\n      }\n      // Try to start processing if possible\n      if (queue.length > 0 && activeStreams < maxActiveStreams) {\n        writeNextChunk();\n      }\n      // Schedule more loading if we have more chunks\n      if (currentIndex < parts.length) {\n        setImmediate(loadChunks);\n      }\n    };\n\n    // Handle write stream drain\n    const onDrain = () => {\n      // When writeStream drains, try to pipe more chunks\n      if (queue.length > 0 && activeStreams < maxActiveStreams) {\n        writeNextChunk();\n      }\n      // If no more chunks and no active streams, close the file\n      if (currentIndex >= parts.length && queue.length === 0 && activeStreams === 0) {\n        writeStream.end();\n      }\n    };\n\n    writeStream.on('drain', onDrain);\n\n    writeStream.on('finish', () => {\n      console.log(`✅ File write completed: ${finalPath}`);\n      console.log(`📊 Final file size: ${fileSize} bytes`);\n      \n      // Create file doc after write completes\n      const fileDoc = {\n        user_id: userId,\n        file_name: originalName,\n        file_size: fileSize,\n        file_type: mimetype || 'application/octet-stream',\n        storage_path: safeName,\n        description: description || null,\n        is_public: false,\n        created_at: new Date(),\n        updated_at: new Date(),\n      };\n\n      // Verify file exists before inserting to DB\n      fs.stat(finalPath, (err, stats) => {\n        if (err) {\n          console.error(`❌ File not found after write: ${finalPath}`, err);\n          return;\n        }\n        console.log(`📁 File verified: ${stats.size} bytes`);\n        \n        // Insert to DB\n        db.collection('files').insertOne(fileDoc).catch(err => {\n          console.error('DB insert error:', err);\n        }).then(() => {\n          console.log(`💾 Saved to DB: ${originalName}`);\n        });\n      });\n\n      // Clean up upload session\n      uploadSessions.delete(uploadId);\n      \n      resolveAll({ id: safeName, file_name: originalName, file_size: fileSize });\n    });\n\n    writeStream.on('error', (err) => {\n      console.error(`❌ Write stream error: ${err.message}`);\n      console.error(err.stack);\n      rejectAll(err);\n    });\n\n    loadChunks();\n  });\n}\n\nasync function cleanupOldTempChunks(ageMs = 2 * 60 * 60 * 1000) {\n  try {\n    const files = await fs.promises.readdir(tempChunksDir);\n    const now = Date.now();\n\n    await Promise.all(files.map(async (file) => {\n      if (!file.includes('.part.')) {\n        return;\n      }\n      const filePath = path.join(tempChunksDir, file);\n      try {\n        const stat = await fs.promises.stat(filePath);\n        if (now - stat.mtimeMs > ageMs) {\n          await fs.promises.unlink(filePath);\n        }\n      } catch (err) {\n        // ignore missing file or permission issues\n      }\n    }));\n  } catch (err) {\n    console.error('Error cleaning temp chunk files:', err);\n  }\n}\n\n// Run cleanup once at startup, then periodically every hour\ncleanupOldTempChunks().catch(err => console.error('Startup temp cleanup failed:', err));\nconst fileCleanupInterval = setInterval(() => cleanupOldTempChunks(), 60 * 60 * 1000);\n\n// Cleanup expired upload sessions to prevent memory leaks\nfunction cleanupExpiredUploadSessions(maxAgeMs = 3600000) { // 1 hour default\n  const now = Date.now();\n  let cleaned = 0;\n  for (const [uploadId, session] of uploadSessions.entries()) {\n    if (now - session.createdAt > maxAgeMs) {\n      uploadSessions.delete(uploadId);\n      cleaned++;\n    }\n  }\n  if (cleaned > 0) {\n    console.log(`🧹 Cleaned ${cleaned} expired upload sessions`);\n  }\n}\n\nconst sessionCleanupInterval = setInterval(() => cleanupExpiredUploadSessions(), 60000); // Every minute\n\n// Middleware to verify JWT\nfunction verifyToken(req, res, next) {\n  const token = req.headers['authorization']?.split(' ')[1];\n  if (!token) {\n    return res.status(401).json({ error: 'No token provided' });\n  }\n  try {\n    const decoded = jwt.verify(token, JWT_SECRET);\n    if (!decoded.userId || !decoded.email) {\n      return res.status(401).json({ error: 'Invalid token: missing userId or email' });\n    }\n    req.userId = decoded.userId;\n    req.email = decoded.email;\n    next();\n  } catch (err) {\n    console.warn('Token validation failed:', err.message.substring(0, 100));\n    res.status(401).json({ error: 'Invalid or expired token' });\n  }\n}\n\n// Input sanitizer utility\nfunction sanitizeInput(str, maxLength = 1000) {\n  if (typeof str !== 'string') return '';\n  return str.trim().substring(0, maxLength);\n}\n\n// Auth Routes\n\n// Sign up\napp.post('/auth/signup', async (req, res) => {\n  try {\n    const email = sanitizeInput(req.body.email, 255);\n    const password = sanitizeInput(req.body.password, 256);\n    const displayName = sanitizeInput(req.body.displayName, 100);\n    const username = sanitizeInput(req.body.username, 20);\n\n    // Validate email format\n    if (!email || !/^[^\\s@]+@[^\\s@]+\\.[^\\s@]+$/.test(email)) {\n      return res.status(400).json({ error: 'Invalid email format' });\n    }\n\n    if (!password || password.length < 6) {\n      return res.status(400).json({ error: 'Password must be at least 6 characters' });\n    }\n\n    if (username && !/^[a-zA-Z0-9_]{3,20}$/.test(username)) {\n      return res.status(400).json({ error: 'Username must be 3-20 characters (letters, numbers, underscore only)' });\n    }\n\n    const usersCollection = db.collection('users');\n    const existing = await usersCollection.findOne({ email });\n\n    if (existing) {\n      return res.status(400).json({ error: 'Email already exists' });\n    }\n\n    if (username) {\n      const existingUsername = await usersCollection.findOne({ username });\n      if (existingUsername) {\n        return res.status(400).json({ error: 'Username already taken' });\n      }\n    }\n\n    const hashedPassword = await bcryptjs.hash(password, 10);\n    const user = {\n      email,\n      password: hashedPassword,\n      username: username || null,\n      displayName: displayName || email.split('@')[0],\n      display_name: displayName || email.split('@')[0],\n      bio: '',\n      avatar_url: '',\n      location: '',\n      website: '',\n      phone: '',\n      role: 'user', // Mặc định role là 'user'\n      social_media: {\n        twitter: '',\n        github: '',\n        linkedin: '',\n        instagram: ''\n      },\n      created_at: new Date(),\n      updated_at: new Date(),\n    };\n\n    const result = await usersCollection.insertOne(user);\n    const userId = result.insertedId.toString();\n\n    const token = jwt.sign({ userId, email }, JWT_SECRET, { expiresIn: '7d' });\n\n    res.json({\n      user: {\n        id: userId,\n        email,\n        displayName: user.displayName,\n        username: user.username,\n      },\n      token,\n    });\n  } catch (err) {\n    console.error('Signup error:', err.message);\n    if (err.code === 11000) {\n      const field = Object.keys(err.keyPattern || {})[0] || 'field';\n      res.status(400).json({ error: `${field} already exists` });\n    } else {\n      res.status(500).json({ error: 'Signup failed' });\n    }\n  }\n});\n\n// Sign in\napp.post('/auth/signin', async (req, res) => {\n  try {\n    const { email, password } = req.body;\n\n    if (!email || !password) {\n      return res.status(400).json({ error: 'Email and password required' });\n    }\n\n    const usersCollection = db.collection('users');\n    const user = await usersCollection.findOne({ email });\n\n    if (!user) {\n      return res.status(400).json({ error: 'Invalid credentials' });\n    }\n\n    const isValid = await bcryptjs.compare(password, user.password);\n\n    if (!isValid) {\n      return res.status(400).json({ error: 'Invalid credentials' });\n    }\n\n    const token = jwt.sign({ userId: user._id.toString(), email }, JWT_SECRET, { expiresIn: '7d' });\n\n    res.json({\n      user: {\n        id: user._id.toString(),\n        email: user.email,\n        displayName: user.displayName,\n        username: user.username,\n      },\n      token,\n    });\n  } catch (err) {\n    console.error('Signin error:', err);\n    res.status(500).json({ error: 'Signin failed' });\n  }\n});\n\n// Get current user\napp.get('/auth/me', verifyToken, async (req, res) => {\n  try {\n    const usersCollection = db.collection('users');\n    const user = await usersCollection.findOne({ _id: new ObjectId(req.userId) });\n\n    if (!user) {\n      return res.status(404).json({ error: 'User not found' });\n    }\n\n    // Check if admin\n    res.json({\n      id: user._id.toString(),\n      email: user.email,\n      displayName: user.displayName,\n      username: user.username || '',\n      display_name: user.display_name || user.displayName,\n      bio: user.bio || '',\n      avatar_url: user.avatar_url || '',\n      location: user.location || '',\n      website: user.website || '',\n      phone: user.phone || '',\n      role: user.role || 'user',\n      social_media: user.social_media || { twitter: '', github: '', linkedin: '', instagram: '' },\n      created_at: user.created_at,\n      isAdmin: user.role === 'admin',\n    });\n  } catch (err) {\n    console.error('Get user error:', err);\n    res.status(500).json({ error: 'Failed to fetch user' });\n  }\n});\n\n// Change password\napp.post('/auth/change-password', verifyToken, async (req, res) => {\n  try {\n    const { currentPassword, newPassword } = req.body;\n\n    if (!currentPassword || !newPassword) {\n      return res.status(400).json({ error: 'Current and new password required' });\n    }\n\n    if (newPassword.length < 6) {\n      return res.status(400).json({ error: 'New password must be at least 6 characters' });\n    }\n\n    const usersCollection = db.collection('users');\n    const user = await usersCollection.findOne({ _id: new ObjectId(req.userId) });\n\n    if (!user) {\n      return res.status(404).json({ error: 'User not found' });\n    }\n\n    // Verify current password\n    const isValid = await bcryptjs.compare(currentPassword, user.password);\n    if (!isValid) {\n      return res.status(401).json({ error: 'Current password is incorrect' });\n    }\n\n    // Hash new password\n    const hashedPassword = await bcryptjs.hash(newPassword, 10);\n\n    // Update password\n    await usersCollection.updateOne(\n      { _id: new ObjectId(req.userId) },\n      { $set: { password: hashedPassword, updated_at: new Date() } }\n    );\n\n    res.json({ success: true, message: 'Password changed successfully' });\n  } catch (err) {\n    console.error('Change password error:', err);\n    res.status(500).json({ error: 'Failed to change password' });\n  }\n});\n\n// Update profile\napp.post('/auth/update-profile', verifyToken, async (req, res) => {\n  try {\n    const { display_name, bio, avatar_url, location, website, phone, social_media } = req.body;\n\n    const usersCollection = db.collection('users');\n    const updates = {};\n    \n    if (display_name !== undefined) updates.display_name = display_name;\n    if (bio !== undefined) updates.bio = bio;\n    if (avatar_url !== undefined) updates.avatar_url = avatar_url;\n    if (location !== undefined) updates.location = location;\n    if (website !== undefined) updates.website = website;\n    if (phone !== undefined) updates.phone = phone;\n    if (social_media !== undefined) updates.social_media = social_media;\n    updates.updated_at = new Date();\n\n    await usersCollection.updateOne(\n      { _id: new ObjectId(req.userId) },\n      { $set: updates }\n    );\n\n    // Return updated user\n    const user = await usersCollection.findOne({ _id: new ObjectId(req.userId) });\n\n    res.json({\n      id: user._id.toString(),\n      email: user.email,\n      displayName: user.displayName,\n      username: user.username || '',\n      display_name: user.display_name || user.displayName,\n      bio: user.bio || '',\n      avatar_url: user.avatar_url || '',\n      location: user.location || '',\n      website: user.website || '',\n      phone: user.phone || '',\n      role: user.role || 'user',\n      social_media: user.social_media || { twitter: '', github: '', linkedin: '', instagram: '' },\n      created_at: user.created_at,\n      isAdmin: user.role === 'admin',\n      message: 'Profile updated successfully'\n    });\n  } catch (err) {\n    console.error('Update profile error:', err);\n    if (err.code === 11000) {\n      res.status(400).json({ error: 'Username already taken' });\n    } else {\n      res.status(500).json({ error: 'Failed to update profile' });\n    }\n  }\n});\n\n// File Routes\n\n// Chunked upload support for large files - PARALLEL CHUNK SUPPORT\napp.post('/api/files/upload-chunk', verifyToken, (req, res, next) => {\n  chunkUpload.single('chunk')(req, res, (err) => {\n    if (err) {\n      console.error(`Chunk upload error for user ${req.userId}:`, err.message);\n      if (err.code === 'LIMIT_FILE_SIZE') {\n        return res.status(413).json({ error: `Chunk too large (max: ${(err.limit / 1024 / 1024).toFixed(0)}MB)` });\n      }\n      return res.status(400).json({ error: err.message || 'Chunk upload failed' });\n    }\n    next();\n  });\n}, async (req, res) => {\n  try {\n    const uploadId = sanitizeInput(req.body.uploadId, 100);\n    const chunkIndex = Number(req.body.chunkIndex);\n    const totalChunks = Number(req.body.totalChunks);\n    const originalName = sanitizeInput(req.body.fileName, 255);\n    const description = sanitizeInput(req.body.description, 1000);\n    const isLastChunk = req.body.isLastChunk === 'true';\n\n    // Validate metadata\n    if (!uploadId || Number.isNaN(chunkIndex) || Number.isNaN(totalChunks) || !originalName) {\n      return res.status(400).json({ error: 'Missing or invalid upload metadata' });\n    }\n\n    if (chunkIndex < 0 || chunkIndex >= totalChunks) {\n      return res.status(400).json({ error: 'Invalid chunk index' });\n    }\n\n    if (totalChunks < 1 || totalChunks > 10000) {\n      return res.status(400).json({ error: 'Invalid total chunks (1-10000 allowed)' });\n    }\n\n    if (!req.file) {\n      return res.status(400).json({ error: 'No chunk file provided' });\n    }\n\n    // Rename temp file to correct chunk filename NOW that we have uploadId/chunkIndex\n    const correctChunkName = `${uploadId}.part.${chunkIndex}`;\n    const correctChunkPath = path.join(tempChunksDir, correctChunkName);\n    const tempFilePath = req.file.path;\n    \n    try {\n      await fs.promises.rename(tempFilePath, correctChunkPath);\n      req.file.path = correctChunkPath;\n      req.file.filename = correctChunkName;\n    } catch (renameErr) {\n      console.error(`❌ Failed to rename chunk file: ${renameErr.message}`);\n      return res.status(500).json({ error: 'Failed to save chunk' });\n    }\n\n    console.log(`📥 Received chunk ${chunkIndex + 1}/${totalChunks} for upload ${uploadId.substring(0, 8)}... (${(req.file.size / 1024 / 1024).toFixed(1)}MB)`);\n    console.log(`   Saved to: ${req.file.path}`);\n\n    // Track upload session\n    if (!uploadSessions.has(uploadId)) {\n      uploadSessions.set(uploadId, { \n        chunks: new Set(), \n        totalChunks, \n        userId: req.userId,\n        fileName: originalName,\n        description,\n        mimetype: req.file.mimetype,\n        fileSize: Number(req.body.fileSize),\n        createdAt: Date.now(),\n        finalized: false,\n        finalizedAt: null\n      });\n    }\n\n    const session = uploadSessions.get(uploadId);\n    \n    // Security: Verify upload belongs to current user\n    if (session.userId !== req.userId) {\n      return res.status(403).json({ error: 'Upload does not belong to this user' });\n    }\n\n    session.chunks.add(chunkIndex);\n    const chunksReceived = session.chunks.size;\n    const progress = Math.round((chunksReceived / totalChunks) * 100);\n\n    console.log(`   Progress: ${chunksReceived}/${totalChunks} chunks (${progress}%)`);\n\n    res.json({ \n      chunkIndex, \n      totalChunks, \n      chunksReceived,\n      progress,\n      chunkComplete: false,\n      ready: chunksReceived === totalChunks\n    }).end();\n\n    // Async finalize if all chunks received\n    // But verify actual chunk files exist (not just in-memory count) since we have clustering\n    if (chunksReceived === totalChunks) {\n      console.log(`🚀 Memory counter: All chunks received for ${uploadId.substring(0, 8)}... - Verifying chunk files...`);\n      \n      // Verify all chunks actually exist on disk (async!)\n      setImmediate(async () => {\n        const allChunkPaths = Array.from({ length: totalChunks }, (_, i) =>\n          path.join(tempChunksDir, `${uploadId}.part.${i}`)\n        );\n        \n        const missingChunks = [];\n        for (const chunkPath of allChunkPaths) {\n          if (!fs.existsSync(chunkPath)) {\n            missingChunks.push(chunkPath);\n          }\n        }\n        \n        if (missingChunks.length > 0) {\n          console.warn(`⚠️ Memory says all ${totalChunks} chunks ready, but ${missingChunks.length} missing on disk!`);\n          console.warn(`   Missing: ${missingChunks.slice(0, 3).join(', ')}...`);\n          // Don't finalize yet - files might still be arriving from other workers\n          return;\n        }\n        \n        console.log(`✅ All ${totalChunks} chunks verified on disk - Starting finalization...`);\n        try {\n          console.log(`[FINALIZE] Starting for ${uploadId}, chunks=${totalChunks}, name=${session.fileName}`);\n          const result = await tryFinalizeChunkedUpload({\n            uploadId,\n            totalChunks,\n            originalName: session.fileName,\n            description: session.description,\n            mimetype: session.mimetype,\n            userId: session.userId,\n            fileSize: session.fileSize || Number(req.body.fileSize),\n          });\n\n          if (result) {\n            // Mark upload as finalized\n            const sessionCheck = uploadSessions.get(uploadId);\n            if (sessionCheck) {\n              sessionCheck.finalized = true;\n              sessionCheck.finalizedAt = Date.now();\n            }\n            console.log(`✅ Upload complete: ${session.fileName} (${chunksReceived} chunks, user: ${req.userId})`);\n          } else {\n            console.error(`[FINALIZE] Failed - result is null`);\n          }\n        } catch (err) {\n          console.error(`❌ Finalize error for ${uploadId}:`, err.message);\n          console.error(`[FINALIZE] Stack:`, err.stack);\n          uploadSessions.delete(uploadId);\n        }\n      });\n    }\n  } catch (err) {\n    console.error('Chunk upload error:', err.message);\n    res.status(500).json({ error: 'Chunk upload failed: ' + err.message });\n  }\n});\n\n// Check upload progress endpoint\napp.get('/api/files/upload-progress/:uploadId', verifyToken, (req, res) => {\n  const uploadId = req.params.uploadId;\n  const session = uploadSessions.get(uploadId);\n\n  if (!session) {\n    return res.status(404).json({ error: 'Upload session not found' });\n  }\n\n  if (session.userId !== req.userId) {\n    return res.status(403).json({ error: 'Unauthorized' });\n  }\n\n  const progress = Math.round((session.chunks.size / session.totalChunks) * 100);\n\n  res.json({\n    uploadId,\n    chunksReceived: session.chunks.size,\n    totalChunks: session.totalChunks,\n    progress,\n    complete: session.chunks.size === session.totalChunks,\n    missingChunks: Array.from({ length: session.totalChunks }, (_, i) => i).filter(i => !session.chunks.has(i))\n  });\n});\n\n// Upload file - Memory-efficient streaming\napp.post('/api/files/upload', verifyToken, (req, res, next) => {\n  upload.single('file')(req, res, (err) => {\n    // Handle multer errors\n    if (err) {\n      console.error('Multer error:', err.message);\n      if (err.code === 'LIMIT_FILE_SIZE') {\n        return res.status(413).json({ error: `File too large. Max size: ${err.limit} bytes` });\n      }\n      if (err.code === 'LIMIT_FILE_COUNT') {\n        return res.status(413).json({ error: 'Too many files' });\n      }\n      return res.status(400).json({ error: err.message || 'Upload failed' });\n    }\n    next();\n  });\n}, async (req, res) => {\n  try {\n    if (!req.file) {\n      return res.status(400).json({ error: 'No file provided' });\n    }\n\n    const { description } = req.body;\n    const filesCollection = db.collection('files');\n\n    // Get actual file size from disk\n    const actualSize = req.file.size;\n\n    const fileDoc = {\n      user_id: req.userId,\n      file_name: req.file.originalname,\n      file_size: actualSize,\n      file_type: req.file.mimetype,\n      storage_path: req.file.filename,\n      description: description || null,\n      is_public: false,\n      created_at: new Date(),\n      updated_at: new Date(),\n    };\n\n    // Fast async insert - doesn't wait for completion\n    filesCollection.insertOne(fileDoc).catch(err => console.error('DB insert error:', err));\n\n    // Send response immediately - data saves in background\n    res.json({\n      id: req.file.filename,\n      file_name: fileDoc.file_name,\n      file_size: fileDoc.file_size,\n    }).end();\n  } catch (err) {\n    console.error('Upload error:', err);\n    if (req.file && req.file.path) {\n      // Async cleanup - don't block response\n      fs.unlink(req.file.path, () => {});\n    }\n    res.status(500).json({ error: 'Upload failed' });\n  }\n});\n\n// Get files\napp.get('/api/files', verifyToken, async (req, res) => {\n  try {\n    const filesCollection = db.collection('files');\n    let query = {};\n\n    // Check if admin\n    const user = await db.collection('users').findOne({ _id: new ObjectId(req.userId) });\n    const isAdmin = user?.role === 'admin';\n\n    if (!isAdmin) {\n      query.user_id = req.userId;\n    }\n\n    const files = await filesCollection\n      .find(query)\n      .sort({ created_at: -1 })\n      .toArray();\n\n    const formattedFiles = files.map(f => ({\n      id: f._id.toString(),\n      ...f,\n      _id: undefined,\n    }));\n\n    res.json(formattedFiles);\n  } catch (err) {\n    console.error('Get files error:', err);\n    res.status(500).json({ error: 'Failed to fetch files' });\n  }\n});\n\n// Delete file\napp.delete('/api/files/:id', verifyToken, async (req, res) => {\n  try {\n    const filesCollection = db.collection('files');\n    const fileDoc = await filesCollection.findOne({ _id: new ObjectId(req.params.id) });\n\n    if (!fileDoc) {\n      return res.status(404).json({ error: 'File not found' });\n    }\n\n    // Check ownership or admin\n    const user = await db.collection('users').findOne({ _id: new ObjectId(req.userId) });\n    const isAdmin = user?.role === 'admin';\n\n    if (fileDoc.user_id !== req.userId && !isAdmin) {\n      return res.status(403).json({ error: 'Unauthorized' });\n    }\n\n    // Delete file from disk\n    const filePath = path.join(uploadsDir, fileDoc.storage_path);\n    fs.unlink(filePath, (err) => {\n      if (err) console.error('Error deleting file:', err);\n    });\n\n    await filesCollection.deleteOne({ _id: new ObjectId(req.params.id) });\n\n    res.json({ success: true });\n  } catch (err) {\n    console.error('Delete file error:', err);\n    res.status(500).json({ error: 'Failed to delete file' });\n  }\n});\n\n// Get file by storage path\napp.get('/api/files/download/:filename', (req, res) => {\n  try {\n    const filename = req.params.filename;\n    const filepath = path.join(uploadsDir, filename);\n\n    // Security: ensure the file is within uploads directory\n    if (!path.resolve(filepath).startsWith(path.resolve(uploadsDir))) {\n      return res.status(403).json({ error: 'Access denied' });\n    }\n\n    if (!fs.existsSync(filepath)) {\n      return res.status(404).json({ error: 'File not found' });\n    }\n\n    res.download(filepath);\n  } catch (err) {\n    console.error('Download error:', err);\n    res.status(500).json({ error: 'Download failed' });\n  }\n});\n\n// Admin Routes\n\n// Get all users\napp.get('/api/admin/users', verifyToken, async (req, res) => {\n  try {\n    // Check if admin\n    const user = await db.collection('users').findOne({ _id: new ObjectId(req.userId) });\n    if (user?.role !== 'admin') {\n      return res.status(403).json({ error: 'Unauthorized' });\n    }\n\n    const usersCollection = db.collection('users');\n    const users = await usersCollection\n      .find({}, { projection: { password: 0 } })\n      .toArray();\n\n    const formattedUsers = users.map(u => ({\n      id: u._id.toString(),\n      ...u,\n      _id: undefined,\n      isAdmin: u.role === 'admin',\n    }));\n\n    res.json(formattedUsers);\n  } catch (err) {\n    console.error('Get users error:', err);\n    res.status(500).json({ error: 'Failed to fetch users' });\n  }\n});\n\n// Get admin files\napp.get('/api/admin/files', verifyToken, async (req, res) => {\n  try {\n    // Check if admin\n    const user = await db.collection('users').findOne({ _id: new ObjectId(req.userId) });\n    if (user?.role !== 'admin') {\n      return res.status(403).json({ error: 'Unauthorized' });\n    }\n\n    const filesCollection = db.collection('files');\n    const files = await filesCollection\n      .find({})\n      .sort({ created_at: -1 })\n      .toArray();\n\n    const formattedFiles = files.map(f => ({\n      id: f._id.toString(),\n      ...f,\n      _id: undefined,\n    }));\n\n    res.json(formattedFiles);\n  } catch (err) {\n    console.error('Get admin files error:', err);\n    res.status(500).json({ error: 'Failed to fetch files' });\n  }\n});\n\n// Set user as admin\napp.post('/api/admin/users/:userId/role', verifyToken, async (req, res) => {\n  try {\n    // Check if admin\n    const user = await db.collection('users').findOne({ _id: new ObjectId(req.userId) });\n    if (user?.role !== 'admin') {\n      return res.status(403).json({ error: 'Unauthorized' });\n    }\n\n    const { role } = req.body;\n    const usersCollection = db.collection('users');\n\n    // Validate role\n    if (!['user', 'admin', 'moderator'].includes(role)) {\n      return res.status(400).json({ error: 'Invalid role' });\n    }\n\n    // Update user role\n    await usersCollection.updateOne(\n      { _id: new ObjectId(req.params.userId) },\n      { $set: { role, updated_at: new Date() } }\n    );\n\n    res.json({ success: true, role });\n  } catch (err) {\n    console.error('Set role error:', err);\n    res.status(500).json({ error: 'Failed to update role' });\n  }\n});\n\n// Get detailed user info with file stats (admin only)\napp.get('/api/admin/users/:userId/detail', verifyToken, async (req, res) => {\n  try {\n    // Check if admin\n    const admin = await db.collection('users').findOne({ _id: new ObjectId(req.userId) });\n    if (admin?.role !== 'admin') {\n      return res.status(403).json({ error: 'Unauthorized' });\n    }\n\n    const targetUser = await db.collection('users').findOne(\n      { _id: new ObjectId(req.params.userId) },\n      { projection: { password: 0 } }\n    );\n\n    if (!targetUser) {\n      return res.status(404).json({ error: 'User not found' });\n    }\n\n    // Get user's files\n    const userFiles = await db.collection('files')\n      .find({ user_id: req.params.userId })\n      .sort({ created_at: -1 })\n      .toArray();\n\n    const totalStorage = userFiles.reduce((sum, f) => sum + (f.file_size || 0), 0);\n    const averageSize = userFiles.length > 0 ? totalStorage / userFiles.length : 0;\n\n    res.json({\n      id: targetUser._id.toString(),\n      email: targetUser.email,\n      displayName: targetUser.displayName,\n      username: targetUser.username,\n      role: targetUser.role,\n      isAdmin: targetUser.role === 'admin',\n      bio: targetUser.bio,\n      avatar_url: targetUser.avatar_url,\n      location: targetUser.location,\n      website: targetUser.website,\n      phone: targetUser.phone,\n      created_at: targetUser.created_at,\n      updated_at: targetUser.updated_at,\n      stats: {\n        totalFiles: userFiles.length,\n        totalStorage,\n        averageFileSize: averageSize,\n        recentFiles: userFiles.slice(0, 5).map(f => ({\n          id: f._id.toString(),\n          name: f.file_name,\n          size: f.file_size,\n          type: f.file_type,\n          created_at: f.created_at,\n        })),\n      },\n    });\n  } catch (err) {\n    console.error('Get user detail error:', err);\n    res.status(500).json({ error: 'Failed to fetch user details' });\n  }\n});\n\n// Delete user file (admin only)\napp.delete('/api/admin/files/:fileId', verifyToken, async (req, res) => {\n  try {\n    // Check if admin\n    const admin = await db.collection('users').findOne({ _id: new ObjectId(req.userId) });\n    if (admin?.role !== 'admin') {\n      return res.status(403).json({ error: 'Unauthorized' });\n    }\n\n    const fileDoc = await db.collection('files').findOne({ _id: new ObjectId(req.params.fileId) });\n\n    if (!fileDoc) {\n      return res.status(404).json({ error: 'File not found' });\n    }\n\n    // Delete file from disk\n    const filePath = path.join(uploadsDir, fileDoc.storage_path);\n    fs.unlink(filePath, (err) => {\n      if (err) console.error('Error deleting file:', err);\n    });\n\n    // Delete from database\n    await db.collection('files').deleteOne({ _id: new ObjectId(req.params.fileId) });\n\n    res.json({ success: true, message: 'File deleted successfully' });\n  } catch (err) {\n    console.error('Delete file error:', err);\n    res.status(500).json({ error: 'Failed to delete file' });\n  }\n});\n\n// Delete all user files (admin only)\napp.post('/api/admin/users/:userId/delete-all-files', verifyToken, async (req, res) => {\n  try {\n    // Check if admin\n    const admin = await db.collection('users').findOne({ _id: new ObjectId(req.userId) });\n    if (admin?.role !== 'admin') {\n      return res.status(403).json({ error: 'Unauthorized' });\n    }\n\n    // Get all files for this user\n    const userFiles = await db.collection('files')\n      .find({ user_id: req.params.userId })\n      .toArray();\n\n    // Delete files from disk\n    let deletedCount = 0;\n    for (const file of userFiles) {\n      const filePath = path.join(uploadsDir, file.storage_path);\n      fs.unlink(filePath, (err) => {\n        if (err) console.error('Error deleting file:', err);\n      });\n      deletedCount++;\n    }\n\n    // Delete all from database\n    const result = await db.collection('files').deleteMany({ user_id: req.params.userId });\n\n    res.json({ \n      success: true, \n      message: `Deleted ${result.deletedCount} files`,\n      deletedCount: result.deletedCount \n    });\n  } catch (err) {\n    console.error('Delete all files error:', err);\n    res.status(500).json({ error: 'Failed to delete files' });\n  }\n});\n\n// Get all user files (admin only)\napp.get('/api/admin/users/:userId/files', verifyToken, async (req, res) => {\n  try {\n    // Check if admin\n    const admin = await db.collection('users').findOne({ _id: new ObjectId(req.userId) });\n    if (admin?.role !== 'admin') {\n      return res.status(403).json({ error: 'Unauthorized' });\n    }\n\n    const files = await db.collection('files')\n      .find({ user_id: req.params.userId })\n      .sort({ created_at: -1 })\n      .toArray();\n\n    const formattedFiles = files.map(f => ({\n      id: f._id.toString(),\n      ...f,\n      _id: undefined,\n    }));\n\n    res.json(formattedFiles);\n  } catch (err) {\n    console.error('Get user files error:', err);\n    res.status(500).json({ error: 'Failed to fetch user files' });\n  }\n});\n\n// Health check\napp.get('/health', (req, res) => {\n  res.json({ status: 'ok' });\n});\n\n// Health check with stats\napp.get('/health/stats', (req, res) => {\n  const activeSessions = uploadSessions.size;\n  let totalChunksInProgress = 0;\n  let totalSize = 0;\n  \n  for (const [, session] of uploadSessions.entries()) {\n    totalChunksInProgress += session.chunks.size;\n    totalSize += session.fileSize || 0;\n  }\n  \n  res.json({\n    status: 'ok',\n    uptime: process.uptime(),\n    memory: process.memoryUsage(),\n    pid: process.pid,\n    database: {\n      schema: 'Embedded role in users collection (no separate user_roles)',\n      roles: ['user', 'admin', 'moderator'],\n    },\n    uploads: {\n      activeSessions,\n      chunksInProgress: totalChunksInProgress,\n      totalSizeInProgress: Math.round(totalSize / 1024 / 1024) + ' MB',\n      concurrency: {\n        maxConcurrentFiles: 8,\n        chunkConcurrencyStrategy: 'adaptive (8-10 for 1 file, 6 for 2-3, 4 for 4+)',\n        maxParallelChunkMerges: 4,\n        uploadBuffers: { chunk: '96MB', merge: '16MB', readPerStream: '16MB' }\n      }\n    }\n  });\n});\n\n// ⚡ ULTRA-PERFORMANCE: Clustering + Worker Threads\nconst numCPUs = os.cpus().length;\n// DISABLE clustering for now - file uploads need shared session state across workers\n// TODO: Use Redis for shared uploadSessions if clustering needed\nconst enableClustering = false; // process.env.ENABLE_CLUSTERING !== 'false';\n\nif (enableClustering && cluster.isPrimary) {\n  console.log(`🚀 Master process ${process.pid} starting...`);\n  console.log(`📊 Spawning ${numCPUs} worker processes...`);\n  \n  // Spawn workers\n  for (let i = 0; i < numCPUs; i++) {\n    cluster.fork();\n  }\n\n  // Handle worker restart\n  cluster.on('exit', (worker, code, signal) => {\n    if (signal) {\n      console.log(`⚠️ Worker ${worker.process.pid} killed by signal: ${signal}`);\n    } else if (code !== 0) {\n      console.log(`⚠️ Worker ${worker.process.pid} exited with error code: ${code}`);\n      console.log('🔄 Spawning replacement...');\n      cluster.fork();\n    }\n  });\n\n  // Status logger\n  setInterval(() => {\n    console.log(`📈 Workers: ${Object.keys(cluster.workers).length} | Memory: ${Math.round(process.memoryUsage().heapUsed / 1024 / 1024)}MB`);\n  }, 30000);\n} else {\n  // Worker process\n  initMongoDB().then(() => {\n    const server = app.listen(PORT, () => {\n      const workerId = cluster.isPrimary ? 'primary' : cluster.worker?.id;\n      console.log(`✅ Worker process ${process.pid} (ID: ${workerId}) running on http://localhost:${PORT}`);\n    });\n\n    // Socket handling optimization\n    const maxConnections = 10000;\n    server.maxConnections = maxConnections;\n\n    // Keep-alive settings - aggressive for high-throughput uploads\n    server.keepAliveTimeout = 120000; // 2 min keep-alive for connection reuse\n    server.headersTimeout = 125000;\n\n    // Error handling\n    server.on('error', (err) => {\n      console.error('Server error:', err);\n    });\n\n    // Graceful shutdown\n    process.on('SIGTERM', () => {\n      console.log(`🛑 Worker ${process.pid} received SIGTERM, shutting down gracefully...`);\n      \n      // Cleanup intervals\n      clearInterval(fileCleanupInterval);\n      clearInterval(sessionCleanupInterval);\n      \n      server.close(async () => {\n        console.log(`✅ Worker ${process.pid} server closed`);\n        if (mongoClient) {\n          await mongoClient.close();\n        }\n        process.exit(0);\n      });\n\n      // Force shutdown after 30 seconds\n      setTimeout(() => {\n        console.error('❌ Forced shutdown after 30s');\n        process.exit(1);\n      }, 30000);\n    });\n\n    // Handle other termination signals\n    process.on('SIGINT', () => {\n      console.log(`🛑 Worker ${process.pid} received SIGINT`);\n      clearInterval(fileCleanupInterval);\n      clearInterval(sessionCleanupInterval);\n      process.exit(0);\n    });\n  });\n}\n\n",
   "language": "javascript",
   "createdAt": 1776244783913,
+  "updatedAt": 1776518462971
 }