auderuy Makka

I made these roof tails and some of them are unclosed, I try to use foreach connected piece and Polyfill to fill the hole, but I don't know how to determine if there are unshared edges on them. How can I determine or is there any better ways to fill them.

How can I cut a regular polygon with only one primitive into multiple rectangles?
the shape is a randomly generated superposition of multiple rectangles so I can't use addprim ,addvertex to cut it