EBS solution for Vendor Rebate

Hello,
  When contemplating a solution in E-Business suite that will automate vendor rebate one would wonder if Oracle Contracts is a must use or the current 12.1+ functionality in purchasing is sufficient to capture contracts details for terms, rules and formulas to calculate rebates. The other piece will be if a rebate calculation engine is present to calculate the rebates on those contracts per the terms and formulas specified on the contracts. Finally, the calculations done for vendor contract rebates need to create credit memo that the supplier gets notified electronically. What we are not sure about is what functionality