title: optaplanner for calculating best discount
body: <p>I'm looking to use optaplanner to help calculate the best discount for a user buying a list of items  (e.g. A Shopping Cart).</p>
  
  <p>Does this sound like a good idea?  Has any tried it?  Any help would be greatly appreciated.</p>
  
  <p><strong>Consider:</strong></p>
  
  <ul>
  <li>I have a user wanting to buy a number of different items </li>
  <li><p>There are a number of Promotional Discounts available to this customer including: Percentage Discount and Buy-one-get-one-free on a number of the items</p>
  
  <p>-</p></li>
  <li>Each discount may only apply to some of the items</li>
  <li>Each item can only have one Promotion applied</li>
  <li>But each Promotion may be applied to multiple items.  The same Percentage Discount may be available to multiple items</li>
  <li>Applying each Promotion in different orders may result in a different total discount</li>
  </ul>
  
  <p><strong>Goal</strong> : I want to identify which Promotions applied in a certain order will give the user the greatest discount.</p>
  
  <p>I have looked at both drools-expert (considering the brute force option) and optaplanner.  With optaplanner I do not see how I can do the following:</p>
  
  <ul>
  <li>Take into account that a Promotion may apply to multiple items</li>
  <li>Discount gained from a Promotion may differ depending on the state of the basket (i.e. which promotions have already been applied) when it is applied.</li>
  </ul>