static public function getUploadFileUrl($filename)
    {
        if ($filename && strpos($filename, 'http') !== 0) {
            
            $filename = static::getUploadFileRelativePath($filename);
            
            if (static::isRootImageFile($filename)) {
                
                return static::getRootUrl() . '/' . $filename;
            }
            
            $filename = static::getUploadUrl(true) . '/' . $filename;
        }
        
        return $filename;
    }