Code Review Prompt (Gemini)

language: TypeScript
context: Express.js route handler for user login
code:
async function login(req, res) {
  const user = await db.query('SELECT * FROM users WHERE email = ' + req.body.email);
  if (user && user.password === req.body.password) {
    res.json({ token: jwt.sign({ id: user.id }, 'secret') });
  }
}

**1. Security — SQL Injection [critical]**
Location: db.query call
Issue: String concatenation builds the SQL query directly from user input, allowing an attacker to bypass authentication or dump the database.
Fix: Use parameterised queries: `db.query('SELECT * FROM users WHERE email = $1', [req.body.email])`

**2. Security — Hardcoded JWT Secret [critical]**
Location: jwt.sign call
Issue: The secret 'secret' is hardcoded. Anyone with access to the source code can forge tokens.
Fix: Load from environment: `process.env.JWT_SECRET`

**3. Security — Plain-text Password Comparison [critical]**
Location: user.password === req.body.password
Issue: Passwords must be hashed. This comparison only works if passwords are stored in plain text, which is a severe breach.
Fix: Use bcrypt: `await bcrypt.compare(req.body.password, user.password)`