To teach myself basic game programming, I am going to program a clone of Pong. I will use the Observer design pattern, with an interface between the input and the game engine. However, I'm not sure what the interface should do. One idea I had was for the input interface to tell the game engine that (e.g.) the screen was clicked, then to let the game engine decide what to do with that information (shoot a bullet, for example). Another idea I had was for the input interface, having caught the mouse click, to tell the game engine to shoot a bullet.

Which method would be better for me to use?