Validation before discount applies

Hello Claudio!
I would like to know whether is there a way to apply the discount (on a specific payment method) based on a previous validation.
Let’s say, we could add a field (similar to a coupon field) that whenever the input is validated, the discount applies.
In this way, we could ask the user to provide, for example, first digits of credit card (bin number) and if those numbers are validated, the discount applies for a specific payment method.
Thanks