server.js

const express = require('express');
const multer = require('multer');
const path = require('path');
const cors = require('cors');
const fs = require('fs');

const app = express();
app.use(cors());
app.use('/uploads', express.static('uploads'));

// Ensure uploads directory exists
if (!fs.existsSync('uploads')) fs.mkdirSync('uploads');

const storage = multer.diskStorage({
  destination: (req, file, cb) => cb(null, 'uploads/'),
  filename: (req, file, cb) => cb(null, Date.now() + '-' + file.originalname)
});

const fileFilter = (req, file, cb) => {
  const allowed = ['image/jpeg', 'image/png', 'image/gif', 'application/pdf'];
  cb(null, allowed.includes(file.mimetype));
};

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

app.post('/upload', upload.single('file'), (req, res) => {
  if (!req.file) return res.status(400).json({ error: 'Invalid file type or no file uploaded.' });
  res.json({ url: `/uploads/${req.file.filename}`, name: req.file.originalname });
});

// Error handling middleware
app.use((err, req, res, next) => {
  if (err instanceof multer.MulterError) {
    if (err.code === 'LIMIT_FILE_SIZE') return res.status(400).json({ error: 'File too large (max 5MB).' });
    return res.status(400).json({ error: err.message });
  }
  res.status(500).json({ error: 'Server error.' });
});

app.listen(4000, () => console.log('Server running on http://localhost:4000'));