<?php
session_start();
require_once '../../db.php';
require_once '../models/User.php';
require_once '../models/Referral.php';

$database = new Database();
$db = $database->getConnection();

$referrer = null;
$referral_code = isset($_GET['ref']) ? $_GET['ref'] : '';

// Check if referral code is valid
if (!empty($referral_code)) {
    $user = new User($db);
    $referrer = $user->getUserByReferralCode($referral_code);
}

if ($_POST) {
    // Handle registration logic here
    $username = $_POST['username'];
    $email = $_POST['email'];
    $password = password_hash($_POST['password'], PASSWORD_DEFAULT);
    
    // Create new user
    $new_user = new User($db);
    // ... your registration logic
    
    // If registration successful and referral code was used
    if (!empty($referral_code) && $referrer) {
        $referral = new Referral($db);
        $referral->createReferral($referrer['id'], $new_user_id);
        
        $_SESSION['message'] = "Welcome! You were referred by " . $referrer['username'];
    }
}
?>

<!-- Your registration form HTML -->