Detecting irregular shape collisions might be difficult(hence why I suggested checking that your library hopefully does. It's a pity it doesn't).

I found this, if you're curious on reading:
http://seb.ly/2009/05/super-fast-tri...rsection-test/

There's a lot you can probably find on shape collision on google. The languages might be different but the logic is always the same.

I mean, it sounds like you're dealing with some complicated interactions(balls and rotating rectangles and such), if you're interested in doing even some basic physics stuff involving these objects interacting it might be beneficial looking into a library that will help you out.

Anyways, if you want to try to start working it out yourself, then imo the first thing I would do is work out whether a single point(your mouse) is within a shape.

After that, you just need to create bounding shapes out of a group of these points.