Transition Epic only when stories are in certain state

I am looking for a method to control the transitioning of Epics based on the state of the user stories attached to them. Here is the set of transitions for Tasks/Stories:

On Task -> done, transition parent issue to done.
On Story -> done, do not transition unless all tasks are also done.

In this way, the story is automatically moved to done when the last task is done.

I cannot do this for Epics, however, as there is no condition equivalent to "Sub-Task Blocking Condition".