Invoice Layout: VAT and Discount Calculation Logic Adjustment

I want the invoice layout to show the unit price excluding VAT, calculate VAT on that full amount, and display the total (unit price + VAT) before any discount in the Purchase Details (top box). Then, in the Summary (bottom box), I want it to display the total amount before discount, apply the discount, recalculate VAT on the discounted subtotal, and display the final Amount Paid. This is important for clarity and accuracy.