On site and external file size checker

human_filesize

function get_file_size($url, $internal = true)
{

    if ($internal) {
        $path        = parse_url($url, PHP_URL_PATH);
        $server_path = $_SERVER['DOCUMENT_ROOT'] . $path;

        if (file_exists($server_path)) {
            return size_format(filesize($server_path));
        }

        return null;
    }

    $ch = curl_init();
    curl_setopt($ch, CURLOPT_HEADER, true);
    curl_setopt($ch, CURLOPT_NOBODY, true);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_exec($ch);

    $size = curl_getinfo($ch, CURLINFO_CONTENT_LENGTH_DOWNLOAD);

    if ($size > 0) {
        return size_format($size);
    }

    return null;
}