import bcrypt from 'bcryptjs';
import jwt from 'jsonwebtoken';
import { sql } from '@vercel/postgres';

const JWT_SECRET = process.env.JWT_SECRET || 'your-secret-key-change-in-production';

export default async function handler(req, res) {
  // Set CORS headers
  res.setHeader('Access-Control-Allow-Origin', '*');
  res.setHeader('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS');
  res.setHeader('Access-Control-Allow-Headers', 'Content-Type, Authorization');

  // Handle preflight requests
  if (req.method === 'OPTIONS') {
    res.status(200).end();
    return;
  }

  if (req.method !== 'POST') {
    return res.status(405).json({ error: 'Method not allowed' });
  }

  try {
    const { email, password } = req.body;

    if (!email || !password) {
      return res.status(400).json({ error: 'Email and password are required' });
    }

    if (password.length < 6) {
      return res.status(400).json({ error: 'Password must be at least 6 characters' });
    }

    // Check if user already exists
    const existingUser = await sql`
      SELECT id FROM users WHERE email = ${email}
    `;

    if (existingUser.rows.length > 0) {
      return res.status(409).json({ error: 'User already exists' });
    }

    // Hash password
    const hashedPassword = await bcrypt.hash(password, 12);

    // Create user
    const result = await sql`
      INSERT INTO users (email, password, role) 
      VALUES (${email}, ${hashedPassword}, ${'user'})
      RETURNING id, email, role, created_at
    `;

    const user = result.rows[0];

    // Generate JWT token
    const token = jwt.sign(
      { userId: user.id, email: user.email, role: user.role },
      JWT_SECRET,
      { expiresIn: '24h' }
    );

    res.status(201).json({
      success: true,
      user,
      token
    });

  } catch (error) {
    console.error('Registration error:', error);
    res.status(500).json({ error: 'Internal server error' });
  }
}