Help with Flying Entity Landing

Hey all! I'm working on a flying entity, and I'd like it to be able to land on blocks (like how bats hang upside-down from blocks except on the top of them) and be able to stay there, until a random amount of time has passed and it decides to fly again. 

This is my code so far to detect if an entity is flying, but I can't figure out how to make it land. I'm not a great coder, so any reworks are welcome!