Puzzle of the Week #477 - Twenty Sum Thing

Fill in all the empty squares of the grid with the digits 1-9, such that:

 1:            A diamond shape denotes that the four numbers adjacent to it add to 20.

2:            Every diamond uses a different way to add to 20, so if for example one diamond is surrounded by 1,2,8,9, no other diamonds can use those same four numbers, not even in a different order.

3:            Identical digits are not allowed to occupy adjacent squares of the grid, not even diagonally adjacent.