referral code

Hey guys, What would you suggest me to build the following script: Build a kind of plugin that generates a unique referral link for every visitor and redirects after a certain number of referred visitors have visited the exact website where the first visitor was given the option to generate...

Anyone know a way to attach a cookie to autofill referral code or other way to have the app, after installed, to have a ref code in the form when they create account? Thanks!