Affiliate module but with discount codes.

[beepow]

Hi,
I'm looking for an affiliate module that allows promoters to use discount codes to boost sales. At the end of the month, promoters will receive a commission based on the total amount of sales made with their codes. So the module should easily show the number and the amount of sales generated by these codes. 
All the affiliate module I'm checking seems to works mainly with referral URLs and loyalty points. But the promoters of this store meets customers in person, so referral url can't be used. There will also be an affiliate program with some websites, but even in this case the shop owner would prefer to manage the promoters' sales and related commissions with the codes used.

The shop is going to be soon upgraded from 1.6 to 8.