Payment Method Discount based on Shipping Option

[skecchi]

I was wondering if anyone has a quick solution to this.

I want to make a discount where both shipping method and payment methods are considered. Easier to show a situation than explain what I mean.

I have 3 shipping options:
- Delivery
- Ship by Canada Post
- Ship by DHL

and I have 2 payment options:
- Paypal
- Cash on Delivery

I want a 10% Discount to apply if the shipping option selected is "Delivery" and the Payment Option selected is "Paypal"

One non-complicated way to do this would be to have 2 Paypal payment methods and have one or the other be available depending on shipping method.

Problem is- I'm not really good at PHP so how to do this is beyond me.

Any ideas or tips on how to achieve this?