processing submitted links

I'm working on a wiki for my company. I have the editor in place, image uploading, saving/restoring from the db, etc all working. The last bit is handling links between topics in the wiki.

Right now, when a user submits a URL, the link generated is something like:

<a href='somelink'>text</a>

What I'd like is for it to generate something more akin to:

<a href="wiki.php?topic=somelink">text</a>

ie, prepend the 'wiki.php?topic='

Any way to do that via the configuration files? Or even better would be to convert all links to a javascript call, so that logic within a javascript function can handle the linking. If its not possible via configuration files, any ideas on how to alter the .js files to make it do this would be appreciated. I had also considered doing the processing on the server side when the new content is submitted, but I would like to avoid that.