const multer = require('multer');
const path = require('path');
const fs = require('fs');
const { v4: uuidv4 } = require('uuid');

// Create uploads directory if it doesn't exist
const uploadDir = process.env.UPLOAD_DIR || './uploads';
const documentsDir = path.join(uploadDir, 'documents');
const profilesDir = path.join(uploadDir, 'profiles');
const tempDir = path.join(uploadDir, 'temp');

[uploadDir, documentsDir, profilesDir, tempDir].forEach(dir => {
  if (!fs.existsSync(dir)) {
    fs.mkdirSync(dir, { recursive: true });
  }
});

// Storage configuration
const storage = multer.diskStorage({
  destination: (req, file, cb) => {
    let folder = documentsDir;
    
    if (req.body.uploadType === 'profile') {
      folder = profilesDir;
    } else if (req.body.uploadType === 'temp') {
      folder = tempDir;
    }
    
    cb(null, folder);
  },
  filename: (req, file, cb) => {
    const uniqueId = uuidv4();
    const ext = path.extname(file.originalname);
    const filename = `${uniqueId}${ext}`;
    cb(null, filename);
  }
});

// File filter
const fileFilter = (req, file, cb) => {
  // Allowed file types
  const allowedTypes = [
    'application/pdf',
    'image/jpeg',
    'image/jpg',
    'image/png',
    'application/msword',
    'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
    'application/vnd.ms-excel',
    'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
  ];

  if (allowedTypes.includes(file.mimetype)) {
    cb(null, true);
  } else {
    cb(new Error('Invalid file type. Only PDF, JPG, PNG, DOC, DOCX, XLS, XLSX allowed'), false);
  }
};

// Multer upload configuration
const upload = multer({
  storage: storage,
  limits: {
    fileSize: parseInt(process.env.MAX_FILE_SIZE) || 10 * 1024 * 1024 // 10MB default
  },
  fileFilter: fileFilter
});

// Single file upload
const uploadSingle = upload.single('file');

// Multiple files upload
const uploadMultiple = upload.array('files', 10); // Max 10 files

// Error handler for multer
const handleUploadError = (err, req, res, next) => {
  if (err instanceof multer.MulterError) {
    if (err.code === 'LIMIT_FILE_SIZE') {
      return res.status(400).json({
        success: false,
        message: 'File too large. Maximum size is 10MB'
      });
    }
    return res.status(400).json({
      success: false,
      message: `Upload error: ${err.message}`
    });
  } else if (err) {
    return res.status(400).json({
      success: false,
      message: err.message
    });
  }
  next();
};

module.exports = {
  uploadSingle,
  uploadMultiple,
  handleUploadError
};