Building weekly schedule based on allocation rules

[nesa47]

Hi all,
I need to build a weekly working schedule in excel based on table of allocation. for example:
In each day i have 7 'a' (a1,a2,a3...) spots, 5 'b' spots and 3 'c' spots. and i have a table that tells be to give 'James' 2 'a' and 1 'b', and so on.
The tricky part is that i need to make sure that each value (James) will get different spots each day -
if James get a1 on Sunday, he cant have a1 until he don't have a choice.

Thanks to the helpers.