all of the instruction of the method should be called when an update happens, I would just like it broken down to a few more methods. the mouse handling could be a method for each case (leaving the input check in the main method. I dont think a single method should span more than one vertical page just for readability. This also gives you a chance to name chunks of code, this helps the code to be self documenting. 

lastly when you do subclass you will be able to override just the parts of code that are different, which is more DRY