Change Main Product Image based on Combination Selected

We have JPGs already made and uploaded based on each attribute combination and the product sku. We only need code that would change the main product image on the product page whenever the customer selects a different shirt color or print color. For example if the customer chooses a Black Shirt, the main image would pull up "product-black-white.jpg" then they select Red Print Color the main image would pull up "sku-black-red.jpg"

That's it. I'd do it myself, but I don't have time to dive back into PHP right now.