<?php
session_start();
require_once __DIR__ . '/db/config.php';

// --- Input Validation ---
if ($_SERVER["REQUEST_METHOD"] !== "POST") {
    header('Location: register.php');
    exit();
}

$name = trim($_POST['name'] ?? '');
$usn = trim($_POST['usn'] ?? '');
$mobile = trim($_POST['mobile'] ?? '');

if (empty($name) || empty($usn) || empty($mobile)) {
    // In a real app, show a proper error message
    die('All fields are required.');
}

// --- Database Interaction ---
try {
    $pdo = db();

    // Check if USN already exists
    $stmt = $pdo->prepare("SELECT id FROM users WHERE usn = ?");
    $stmt->execute([$usn]);
    if ($stmt->fetch()) {
        // For simplicity, we'll just log them in and send to the game.
        // A real app might show an error "USN already registered".
        $stmt = $pdo->prepare("SELECT id FROM users WHERE usn = ?");
        $stmt->execute([$usn]);
        $user = $stmt->fetch();
        $_SESSION['user_id'] = $user['id'];
        header('Location: level1.php'); // Redirect to level 1
        exit();
    }

    // 1. Create a new User (without referral link first)
    $sql = "INSERT INTO users (name, usn, mobile, referralCount, hasWonReward, rewardClaimed, gameLevel) VALUES (?, ?, ?, 0, 'no', 'no', 0)";
    $stmt = $pdo->prepare($sql);
    $stmt->execute([$name, $usn, $mobile]);

    // 2. Get the new User's ID
    $userId = $pdo->lastInsertId();

    // 3. Generate and update the referralLink
    // Note: This assumes the domain is http:// and uses the current host.
    // In a production app, this should be a configurable value.
    $protocol = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off') ? "https" : "http";
    $host = $_SERVER['HTTP_HOST'] ?? 'localhost';
    $referralLink = $protocol . '://' . $host . '?ref=' . $userId;
    
    $updateSql = "UPDATE users SET referralLink = ? WHERE id = ?";
    $updateStmt = $pdo->prepare($updateSql);
    $updateStmt->execute([$referralLink, $userId]);

    // 4. Log this user in by storing their ID in the session
    $_SESSION['user_id'] = $userId;

    // 5. Navigate to Level 1 (placeholder)
    // We will create level1.php in a future step.
    header('Location: level1.php');
    exit();

} catch (PDOException $e) {
    // In a real app, log this error and show a generic error page.
    die("Database error: " . $e->getMessage());
}