<!--<?php-->
// Enhanced Database configuration for XAMPP with additional utilities
<!--class Database {-->
<!--    private $host = "localhost";-->
    // private $db_name = "quiz_platform";
    // private $username = "root";
    // private $password = "";
    // public $conn;
    
<!--    private $db_name = "u333683714_ems2";-->
<!--    private $username = "u333683714_ems2";-->
<!--    private $password = "EMS@New@123";-->
<!--    public $conn;-->


<!--    public function getConnection() {-->
<!--        $this->conn = null;-->
<!--        try {-->
<!--            $this->conn = new PDO("mysql:host=" . $this->host . ";dbname=" . $this->db_name, -->
<!--                                $this->username, $this->password);-->
<!--            $this->conn->exec("set names utf8");-->
<!--            $this->conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);-->
<!--        } catch(PDOException $exception) {-->
<!--            echo "Connection error: " . $exception->getMessage();-->
<!--        }-->
<!--        return $this->conn;-->
<!--    }-->
<!--}-->

// Enhanced Security functions
<!--function sanitize_input($data) {-->
<!--    $data = trim($data);-->
<!--    $data = stripslashes($data);-->
<!--    $data = htmlspecialchars($data);-->
<!--    return $data;-->
<!--}-->

<!--function generate_csrf_token() {-->
<!--    if (!isset($_SESSION['csrf_token'])) {-->
<!--        $_SESSION['csrf_token'] = bin2hex(random_bytes(32));-->
<!--    }-->
<!--    return $_SESSION['csrf_token'];-->
<!--}-->

<!--function verify_csrf_token($token) {-->
<!--    return isset($_SESSION['csrf_token']) && hash_equals($_SESSION['csrf_token'], $token);-->
<!--}-->

<!--function generate_verification_token() {-->
<!--    return bin2hex(random_bytes(32));-->
<!--}-->

<!--function generate_password_reset_token() {-->
<!--    return bin2hex(random_bytes(32));-->
<!--}-->

// Enhanced Authentication functions
<!--function is_logged_in() {-->
<!--    return isset($_SESSION['user_id']) && !empty($_SESSION['user_id']);-->
<!--}-->

<!--function is_admin() {-->
<!--    return isset($_SESSION['role']) && $_SESSION['role'] === 'admin';-->
<!--}-->

<!--function is_instructor() {-->
<!--    return isset($_SESSION['role']) && $_SESSION['role'] === 'instructor';-->
<!--}-->

<!--function is_student() {-->
<!--    return isset($_SESSION['role']) && $_SESSION['role'] === 'student';-->
<!--}-->

<!--function can_manage_exams() {-->
<!--    return is_admin() || is_instructor();-->
<!--}-->

<!--function check_account_lock($user_id) {-->
<!--    $database = new Database();-->
<!--    $db = $database->getConnection();-->
    
<!--    $stmt = $db->prepare("SELECT locked_until FROM users WHERE id = ?");-->
<!--    $stmt->execute([$user_id]);-->
<!--    $result = $stmt->fetch(PDO::FETCH_ASSOC);-->
    
<!--    if ($result && $result['locked_until'] && strtotime($result['locked_until']) > time()) {-->
<!--        return true;-->
<!--    }-->
    
<!--    return false;-->
<!--}-->

<!--function increment_login_attempts($user_id) {-->
<!--    $database = new Database();-->
<!--    $db = $database->getConnection();-->
    
<!--    $stmt = $db->prepare("UPDATE users SET login_attempts = login_attempts + 1 WHERE id = ?");-->
<!--    $stmt->execute([$user_id]);-->
    
    // Check if we need to lock the account
<!--    $stmt = $db->prepare("SELECT login_attempts FROM users WHERE id = ?");-->
<!--    $stmt->execute([$user_id]);-->
<!--    $attempts = $stmt->fetchColumn();-->
    
<!--    if ($attempts >= 5) {-->
<!--        $lock_until = date('Y-m-d H:i:s', strtotime('+30 minutes'));-->
<!--        $stmt = $db->prepare("UPDATE users SET locked_until = ? WHERE id = ?");-->
<!--        $stmt->execute([$lock_until, $user_id]);-->
        return true; // Account locked
<!--    }-->
    
<!--    return false;-->
<!--}-->

<!--function reset_login_attempts($user_id) {-->
<!--    $database = new Database();-->
<!--    $db = $database->getConnection();-->
    
<!--    $stmt = $db->prepare("UPDATE users SET login_attempts = 0, locked_until = NULL WHERE id = ?");-->
<!--    $stmt->execute([$user_id]);-->
<!--}-->

// Audit logging
<!--function log_audit($action, $table_name = null, $record_id = null, $old_values = null, $new_values = null) {-->
<!--    $database = new Database();-->
<!--    $db = $database->getConnection();-->
    
<!--    $stmt = $db->prepare("-->
<!--        INSERT INTO audit_logs (user_id, action, table_name, record_id, old_values, new_values, ip_address, user_agent)-->
<!--        VALUES (?, ?, ?, ?, ?, ?, ?, ?)-->
<!--    ");-->
    
<!--    $user_id = $_SESSION['user_id'] ?? null;-->
<!--    $ip_address = $_SERVER['REMOTE_ADDR'] ?? '';-->
<!--    $user_agent = $_SERVER['HTTP_USER_AGENT'] ?? '';-->
    
<!--    $stmt->execute([-->
<!--        $user_id, $action, $table_name, $record_id,-->
<!--        $old_values ? json_encode($old_values) : null,-->
<!--        $new_values ? json_encode($new_values) : null,-->
<!--        $ip_address, $user_agent-->
<!--    ]);-->
<!--}-->

// Notification system
<!--function create_notification($user_id, $title, $message, $type = 'info', $category = 'system', $action_url = null) {-->
<!--    $database = new Database();-->
<!--    $db = $database->getConnection();-->
    
<!--    $stmt = $db->prepare("-->
<!--        INSERT INTO notifications (user_id, title, message, type, category, action_url)-->
<!--        VALUES (?, ?, ?, ?, ?, ?)-->
<!--    ");-->
    
<!--    return $stmt->execute([$user_id, $title, $message, $type, $category, $action_url]);-->
<!--}-->

<!--function get_unread_notifications($user_id) {-->
<!--    $database = new Database();-->
<!--    $db = $database->getConnection();-->
    
<!--    $stmt = $db->prepare("-->
<!--        SELECT * FROM notifications -->
<!--        WHERE user_id = ? AND is_read = FALSE -->
<!--        AND (expires_at IS NULL OR expires_at > NOW())-->
<!--        ORDER BY created_at DESC-->
<!--    ");-->
<!--    $stmt->execute([$user_id]);-->
    
<!--    return $stmt->fetchAll(PDO::FETCH_ASSOC);-->
<!--}-->

// System settings
<!--function get_setting($key, $default = null) {-->
<!--    $database = new Database();-->
<!--    $db = $database->getConnection();-->
    
<!--    $stmt = $db->prepare("SELECT setting_value FROM system_settings WHERE setting_key = ?");-->
<!--    $stmt->execute([$key]);-->
<!--    $result = $stmt->fetchColumn();-->
    
<!--    return $result !== false ? $result : $default;-->
<!--}-->

<!--function update_setting($key, $value, $description = null) {-->
<!--    $database = new Database();-->
<!--    $db = $database->getConnection();-->
    
<!--    $stmt = $db->prepare("-->
<!--        INSERT INTO system_settings (setting_key, setting_value, description, updated_by)-->
<!--        VALUES (?, ?, ?, ?)-->
<!--        ON DUPLICATE KEY UPDATE-->
<!--        setting_value = VALUES(setting_value),-->
<!--        description = COALESCE(VALUES(description), description),-->
<!--        updated_by = VALUES(updated_by)-->
<!--    ");-->
    
<!--    return $stmt->execute([$key, $value, $description, $_SESSION['user_id'] ?? null]);-->
<!--}-->

// Certificate functions
<!--function generate_certificate_id() {-->
<!--    return 'CERT-' . date('Y') . '-' . strtoupper(substr(uniqid(), -8));-->
<!--}-->

<!--function generate_qr_verification_url($certificate_id) {-->
<!--    $base_url = (isset($_SERVER['HTTPS']) ? 'https' : 'http') . '://' . $_SERVER['HTTP_HOST'];-->
<!--    return $base_url . '/verify_certificate.php?id=' . $certificate_id;-->
<!--}-->

// Start session if not already started
<!--if (session_status() == PHP_SESSION_NONE) {-->
<!--    session_start();-->
<!--}-->

// Check maintenance mode
<!--if (get_setting('maintenance_mode') === 'true' && !is_admin()) {-->
<!--    if (!in_array(basename($_SERVER['PHP_SELF']), ['maintenance.html', 'login.php'])) {-->
<!--        header('Location: maintenance.html');-->
<!--        exit;-->
<!--    }-->
<!--}-->
<!--?>-->


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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
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        <div class="text-center">
            <i class="fas fa-search fa-5x text-muted mb-4"></i>
            <h1 class="display-1 fw-bold text-primary">404</h1>
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