Champion based key bindings

I would like to be able to set key bindings based on what champions i am playing. Depending on which champion i am playing some spells might be regular case, quick cast, smart cast or smart self cast. Also some champions I get more active items so I may bind items to t or y or my 5 button mouse, but that awckward moment when you miss first blood because you forget to reset your key bindings every game.