check_session.php

<?php
// Start session if not already started
if (session_status() === PHP_SESSION_NONE) {
    session_start();
}

// Import isLoggedIn function from config.php instead of redefining it
require_once __DIR__ . '/config.php';

// Redirect to login page with message
function redirectToLogin($message = '') {
    // Determine which login page to redirect to based on role
    $login_page = 'login.php';
    
    if (isset($_SESSION['role'])) {
        if ($_SESSION['role'] === 'Staff') {
            $login_page = 'user_staff.php';
        } elseif ($_SESSION['role'] === 'Student') {
            $login_page = 'user_student.php';
        } elseif ($_SESSION['role'] === 'Admin') {
            $login_page = 'user_admin.php';
        }
    }
    
    // Clear all session variables
    $_SESSION = array();
    
    // Destroy the session
    session_destroy();
    
    // Redirect with message if provided
    if (!empty($message)) {
        header("Location: $login_page?error=" . urlencode($message));
    } else {
        header("Location: $login_page");
    }
    exit;
}

// For pages that require authentication
function requireLogin($required_role = null) {
    if (!isLoggedIn()) {
        redirectToLogin('Please login to continue.');
    }
    
    // Check if user has required role (if specified)
    if ($required_role !== null && $_SESSION['role'] !== $required_role) {
        redirectToLogin('You do not have permission to access this page.');
    }
}
?>