How can I avoid discount to products with Special Price?

[rcpp]

Dear board,

I have this issue: Products that are on sale (have special price) cannot have a discount for promotion (in this case, ot_product_discount). This promotion is available only to a few users, which is the easier part of this issue.

I've thought about adding every product with special price to the exclude table, but that would need a background script to update this table every time a new product have been put on sale. This can lead to some problems I'd like to avoid.

So, I thought about creating a method to just remove the discount from these products on sale. And that is where I'm stuck.

How and where I can tell Konakart to not apply this discount? I'm able to check if the product has a special price, but I'm failing to apply this temporary rule.

I've looked at the documentation, and I think my path would pass by PromotionIf and OrderProductIf. But I'm not good with Java and I'm having some troubles using these intefaces. What I'm not able to accomplish, is telling Konakart to temporary add a product to the Exclude list/rule.

If there is any example I could read, I'd be really thankful.

Thank you in advance!