Small barn repairs

Old small barn in need of some repairs. The horizontal support beam at the bend in the back roof needs to be replaced very very soon. The junction where the beam is (forgive my imprecise description) is the scissors type. The beam that the scissors rest on is what needs to be replaced. That beam rests on wood shelf- like things mounted on the posts. The shelf things look sound to my uneducated eye. It also needs some roof repair. The main roof is slate.