Building a programable IR controller?

I am looking for advice on building an IR project. I am considering purchasing a new lighting setup for my aquarium. The lights are controlled by a remote that uses IR. There is limited program-ability with the factory setup although there is tons of adjust-ability. In other words, if I sit there with the remote I can manually control a million independent functions. But I can't set the unit to control it self through a predefined bunch of functions while I am away.

So what I want to do is build a unit that can "learn" the IR patterns of each command from the stock remote and then be programmed to spit them back in any order at any time I choose. This way I have unlimited control without actually modifying the unit at all. I would prefer something that I could periodically hook up to my computer and change settings on. Also, the project has to have enough storage space/processing power to handle complicated programs that will simulate full day and night cycles, plus things like cloud cover, storms, sunrise/sunset, etc. It has to be able to hold and execute all of these on a schedule that I define.

So, is there any product that would do this that already exists? If not, what would be the best way to proceed? Any help you could supply would be greatly appreciated.