<?php
function getLastSiteUpdate($dir) {
    $lastMod = 0;
    $allowedExtensions = ['php', 'js', 'css']; // only these file types

    $iterator = new RecursiveIteratorIterator(
        new RecursiveDirectoryIterator($dir, FilesystemIterator::SKIP_DOTS)
    );

    foreach ($iterator as $file) {
        if ($file->isFile()) {
            $extension = strtolower(pathinfo($file, PATHINFO_EXTENSION));
            if (in_array($extension, $allowedExtensions)) {
                $fileTime = $file->getMTime();
                if ($fileTime > $lastMod) {
                    $lastMod = $fileTime;
                }
            }
        }
    }
    return $lastMod;
}

$directory = __DIR__;
$lastUpdatedTimestamp = getLastSiteUpdate($directory);

echo date("d F Y", $lastUpdatedTimestamp);
?>