[Closed] Controller Scripts

How would I go about making a controller script that would stop free transforming, ie:

If you’re rigging a character and you don’t want it’s arm IK control to exceed the chain length, as the animator drags the effector and it reaches the limit it should stop/back transform to its proper place.

OR

You want to limit rotation of a non-IK bone, the animator can free transform the bone until it reaches its limit then it stops.

Is this possible? Has anything I just said made any sense?!? Help!