src/middleware/auth.js

const jwt = require('jsonwebtoken');

function authMiddleware(req, res, next) {
  const authHeader = req.headers.authorization;
  if (!authHeader || !authHeader.startsWith('Bearer ')) {
    return res.status(401).json({ message: 'No token provided' });
  }
  const token = authHeader.split(' ')[1];
  try {
    const decoded = jwt.verify(token, process.env.JWT_SECRET);
    req.userId = decoded.userId;
    next();
  } catch {
    return res.status(401).json({ message: 'Invalid or expired token' });
  }
}

module.exports = authMiddleware;