conditional replacement of text
 

I'm running a small poker forum, and need to replace hand history posts to display card images. Luckily, all the cards are alway in brackets i.e. [As Ks], unfortunately replacing them with the replacement variable manager would take forever since some hand histories have up to four cards in between the brackets i.e. [As Ks Qs Js] which would mean like 26,160 replacement variable entries.

So what I'd like to do is somehow automatically check any text within a post that is in brackets for card values and change them to smilies, i.e. [As Ks] converted to :as: :ks: or [7d 5c 3s] converted to :7d: :5c: :3s:

How difficult would this be to do, and what kind of coding languages would be involved?

Thanks for any help in advance.