Dynamic period restriction for few columns

hi experts

Please help with code for dynamic text variable for year, and dynamic restriction for key figure with period variable.

I am having a query and it has year and period as selection variables and i have 6 columns and row( customer).

If user enters year = 2018 and period as 5 then my report heading should be like this.(I am separating headings with , to differentiate the columns here)

Customer, Actual Curr yr 2018, Acutal prior yr 2017, Plan Curr yr 2018, Plan prior yr 2017

1. For column 2 i.e Acutal curr yr 2018 - Here the year is what the user has entered

For column 3 i.e Actual prior yr 2017 - Here we have to minus year by 1 and display as 2017

2. For first column if user enters period as P5, then I need to restict the key figure with P1+P2+P3+P4+P5

For third column the period will be P6+P7+P8+P9+P10+P11+P12+P13.

please help how to write the exit for this 2 requriements.