<?php
/**
 * Authentication Helper
 * TPU Survey System
 */

session_start();

function isLoggedIn() {
    return isset($_SESSION['user_id']);
}

function isAdmin() {
    return isset($_SESSION['role']) && $_SESSION['role'] === 'admin';
}

function isTeacher() {
    return isset($_SESSION['role']) && $_SESSION['role'] === 'teacher';
}

function requireLogin() {
    if (!isLoggedIn()) {
        http_response_code(401);
        header('Content-Type: application/json; charset=utf-8');
        echo json_encode(['error' => 'กรุณาเข้าสู่ระบบ']);
        exit;
    }
}

function requireAdmin() {
    requireLogin();
    if (!isAdmin()) {
        http_response_code(403);
        header('Content-Type: application/json; charset=utf-8');
        echo json_encode(['error' => 'ไม่มีสิทธิ์เข้าถึง']);
        exit;
    }
}

function getCurrentUser() {
    if (!isLoggedIn()) return null;
    return [
        'id' => $_SESSION['user_id'],
        'username' => $_SESSION['username'],
        'role' => $_SESSION['role'],
        'full_name' => $_SESSION['full_name']
    ];
}