const express = require('express');
const cors = require('cors');
const bcrypt = require('bcrypt');
const jwt = require('jsonwebtoken');
const pool = require('./db');
require('dotenv').config();

const app = express();
const PORT = process.env.PORT || 5000;

app.use(cors());
app.use(express.json());

// Registration
app.post('/api/register', async (req, res) => {
  try {
    const { username, email, password } = req.body;
    
    // Check if user exists
    const userExists = await pool.query('SELECT * FROM users WHERE email = $1 OR username = $2', [email, username]);
    if (userExists.rows.length > 0) {
      return res.status(400).json({ error: 'User already exists' });
    }

    // Hash password
    const salt = await bcrypt.genSalt(10);
    const passwordHash = await bcrypt.hash(password, salt);

    // Save to DB
    const newUser = await pool.query(
      'INSERT INTO users (username, email, password_hash) VALUES ($1, $2, $3) RETURNING id, username, email',
      [username, email, passwordHash]
    );

    res.status(201).json({ user: newUser.rows[0] });
  } catch (err) {
    console.error(err);
    res.status(500).json({ error: 'Server error' });
  }
});

// Login
app.post('/api/login', async (req, res) => {
  try {
    const { email, password } = req.body;

    // Find user
    const user = await pool.query('SELECT * FROM users WHERE email = $1', [email]);
    if (user.rows.length === 0) {
      return res.status(400).json({ error: 'Invalid credentials' });
    }

    // Check password
    const validPassword = await bcrypt.compare(password, user.rows[0].password_hash);
    if (!validPassword) {
      return res.status(400).json({ error: 'Invalid credentials' });
    }

    // Create token
    const token = jwt.sign(
      { id: user.rows[0].id, username: user.rows[0].username },
      process.env.JWT_SECRET || 'fallback_secret',
      { expiresIn: '1h' }
    );

    res.json({ token, user: { id: user.rows[0].id, username: user.rows[0].username, email: user.rows[0].email } });
  } catch (err) {
    console.error(err);
    res.status(500).json({ error: 'Server error' });
  }
});

app.listen(PORT, () => {
  console.log(\`Server running on port \${PORT}\`);
});