Reverse group promotion?

[Birman]

There's an option that allows to promote members in a particular group to be promoted to another group after a certain amount of content or a certain amount of time. However, I was wondering if there's an option to reverse the process? There are groups I'd like to keep clean of inactive people. So basically, let's say a member hasn't logged in for 30 days, he/she would get moved to another group then. Is there an option for it hidden somewhere or how difficult would it be to set it up? 

[Christopher Bergsten]

Nothing set up like that at all, but should be fairly easy to set up IMO.

[Birman]

Alright, but do you or anyone else have any idea how to do it? I'm not skilled at php, let alone IPB code. Where should I even start? I imagine I could use the same group changing code and apply a check for "last login" value, but how could I implement it? 

Any help would be greatly appreciated!