How to create nested directories on server based on site hierarchy?

$e = &$modx->Event;
$docid = $e->params['id'];
$dir = $modx->config['rb_base_dir']."images/".$docid;
$folder_permissions = octdec($modx->config['new_folder_permissions']);

function mkdirs($strPath, $mode){ // recursive mkdir function
        if (is_dir($strPath)) return true;
        $pStrPath = dirname($strPath);
        if (!mkdirs($pStrPath, $mode)) return false;
        return @mkdir($strPath);
}

switch ($e->name) {
case "OnDocFormSave":
if($_REQUEST['template'] == 9)
{
  $old_umask = umask(0);
        mkdirs($dir,$folder_permissions);
  umask($old_umask);
  }
  break;
  
  default: "";

  return;
}