Add payment condition to supplier

There is a desire that payment conditions can be added by supplier.
This works as follows:
Example:
Payment condition: 45 days

Discount: 2% within 14 days

The purchase invoice will then automatically show the discount until 14 days after invoice date, after that it will be adjusted to the normal rate.

Other option can be:
Have field come up on the purchase invoice if payment terms are set for the specific suppliers.
Here you can then check/uncheck whether the payment condition should be applied to the purchase invoice. The total amount is then reduced by the discount amount entered.

In both scenarios the Payment Conditions are then preset at the contact itself.