function noFollowLinks($str, $nofollow, $userId){
    if(true) {
        if(strpos($str, "rel")){
            $pattern = '/(?!<<a)rel=.?\".*?\"/';
            $replace = "rel=\"$nofollow\"";
        }
        else {
            $pattern = "/<a /";
            $replace = "<a rel=\"$nofollow\" ";
        }
        return preg_replace($pattern, $replace, $str);
    }
    return $str;
}