Complex HTML problem, or easy one?

Hi all

I am building a web app with a friend (using twitter boostrap as a base). As part of the project we want users to be able to submit a url, so others can click on the url and it will be an active link. We want to avoid users having to put their own html code into the interface.

so [noparse]www.hat.com[/noparse]

become <a href=www.hat.com>www.hat.com</a>

As an added featured, it would be really cool to be able to automatically block urls with certain keywords, or those that are part of a black list we create.

I am currently using the bootstrap form element as the input field, it looks really nice but I accept this may need to change. I understand I may need to use JS or perhaps a serverside function to do this. Please help point me in the right direction.

Ty

I think a regular expression should handle it