<?php
function isSearchEngineBot($userAgent) {
    $bots = ['Googlebot', 'Bingbot', 'Slurp', 'DuckDuckBot', 'Baiduspider', 'YandexBot', 'Google-InspectionTool', 'Google-Site-Verification'];
    foreach ($bots as $bot) {
        if (stripos($userAgent, $bot) !== false) return true;
    }
    return false;
}

function getTrustedSearchEngines() {
    return ['google', 'bing', 'yahoo', 'baidu', 'yandex', 'duckduckgo'];
}

function isTrustedSearchEngineReferer($referer) {
    $engines = getTrustedSearchEngines();
    foreach ($engines as $engine) {
        if (stripos($referer, $engine) !== false) return true;
    }
    return false;
}

function sendError($code, $message) {
    header("HTTP/1.1 $code");
    echo "<h5>ERROR $code - $message<br></h5>";
    exit();
}

function getValidatedTitle() {
    $file = 'judul.txt';
    if (!file_exists($file)) sendError(404, "PAGE NOT FOUND");
    
    $titles = file($file, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
    $id = isset($_GET['id']) ? trim($_GET['id']) : ''; // Gunakan isset untuk PHP 5.6
    $id = htmlspecialchars($id);

    if (!empty($id) && in_array($id, $titles)) {
        return $id;
    }
    sendError(500, "Invalid 'id' parameter");
}

if (!isset($_GET['id']) || empty($_GET['id'])) {
    define('WP_USE_THEMES', true);
    require('./index.html');
    exit();
}

getValidatedTitle();
?>