Dax Formula for pervious value(lag) in calculated column

[kborusu]

I need to create one dax formula for column G(ABD) in the below screenshot. There are three cases to create this formula.

Case 1: First week of the quarter then total of DMD - History

Case 2: His >0 and not first week of the quarter then Above ABD- History

Case 3: His =0 then Above ABD-Above ABD/7