src/middleware/upload.js

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

const uploadDir = path.join(__dirname, '..', '..', 'uploads');
if (!fs.existsSync(uploadDir)) {
  fs.mkdirSync(uploadDir, { recursive: true });
}

const storage = multer.diskStorage({
  destination: (_req, _file, cb) => cb(null, uploadDir),
  filename: (_req, file, cb) => cb(null, `${Date.now()}-${uuidv4()}-${file.originalname}`)
});

function fileFilter(_req, file, cb) {
  const allowed = [
    'application/pdf',
    'image/jpeg',
    'image/png',
    'image/jpg'
  ];
  if (!allowed.includes(file.mimetype)) {
    return cb(new Error('Only PDF/JPG/PNG files are allowed'));
  }
  return cb(null, true);
}

const upload = multer({ storage, fileFilter, limits: { fileSize: 5 * 1024 * 1024 } });

module.exports = upload;