hjælp til oversættelse af link til [url][/url]

Preg
$besked = preg_replace("/<a href=\"(\S+)\" target=\"_blank\">(\S+)<\/a>/i","[url]\\1[/url]",$besked);

Lille test scenarie
<?php
    $besked = 'abc [url]http://www.something.com[/url] def';
   
    echo $besked."<br>";

    $besked = preg_replace("/\[url\](\S+)\[\/url\]/i","<a href=\"\\1\" target=\"_blank\">\\1</a>",$besked);

    echo $besked."<br>";

    $besked = preg_replace("/<a href=\"(\S+)\" target=\"_blank\">(\S+)<\/a>/i","[url]\\1[/url]",$besked);

    echo $besked."<br>";
?>