------------------------------
Most Expensive IN THE CART SAMPLE
------------------------------

1. Say you want to create 'buy 4 or more, get the most expensive in the cart free'

2. create your rule - like this: regular BOGO deal, 'Buy 3 get the next one free'
    You can use this example to guide you:
    http://www.varktech.com/documentation/pricing-deals/examples/#bogo
    look for "Buy a NZ Gala Apple, get the next One Free"
    
      - Be sure to use ADVANCED mode, and to pay attention to the  Buy Group Amount Applies To : All Products or Each, as appropriate
          
      - If you want 'most expensive in the cart',   the 'Get Group' product filter should be 'Any Product'
      
      - If you want 'most expensive in a category', the 'Get Group' product filter should select that category
    
    
3. Take the Rule ID from the rule created in (2) and place it in the code below, replacing the 'XXX' with that number.
    (To find the Rule ID, look at the rule URL, and the number is just after "post=")
 
4. copy the code (from 'code to copy begin' to 'code to copy end', including those lines) to the bottom of your theme functions.php file. 
	(...BUT if there is a " ?>  " line at the bottom of the functions file, this code goes JUST BEFORE the  " ?>  " line.)


5. Done.
  
------------------------------




//CODE TO COPY BEGIN ==>> place in your theme's functions.php file, probably at bottom of file

add_filter('vtprd_additional_actionpop_include_criteria', 'process_additional_actionpop_include_criteria', 10, 3);

function process_additional_actionpop_include_criteria ($return_status, $i, $k) {
  global $vtprd_cart, $vtprd_cart_item, $vtprd_rules_set, $vtprd_rule, $vtprd_info, $vtprd_setup_options;
  $return_status = TRUE;
  
  //$vtprd_rules_set[$i]->post_id = Rule ID
  //$vtprd_cart is the cart contents ==> look at  core/vtprd-cart-classes.php  for cart contents structure
  //   and check this document for examples of how to access the cart data items.
 

      if ( (isset($vtprd_cart->cart_items[$k]->product_id)) &&
           ($vtprd_cart->cart_items[$k]->product_id > ' ') ) {
          $do_nothing = true;
       } else {
          return false;       
      }
  
      switch( $vtprd_rules_set[$i]->post_id ) { 
       
       case 'XXX':    // XXX = REPLACE WITH **RULE ID** FOR 'fake' most expensive RULE described above
       
                $most_expensive_price = 0;
                $most_expensive_id = '';
                foreach($vtprd_cart->cart_items as $vtprd_key => $vtprd_cart_item) { 
                    if ($vtprd_cart_item == '') {
                      continue;
                    } 
                    
                    if ($vtprd_cart_item->unit_price > $most_expensive_price) {
                        $most_expensive_price = $vtprd_cart_item->unit_price;
                        $most_expensive_id    = $vtprd_cart_item->product_id;
                    }
                    
                }
  
                if ($vtprd_cart->cart_items[$k]->product_id == $most_expensive_id) {             
                  $return_status = true; 
                } else {            
                  $return_status = false;
                }
                       
          break;
  
  	    /*
       case '002':    
             //any other rule filter for actionpop goes here     
          break;
  	   */        
    }
    
  return $return_status;
  
}

//CODE TO COPY END





  //**********************
  General tech directions
  //**********************
      ADDTIONAL RULE CRITERIA FILTER - optional, default = TRUE   (useful to add additional checks on a specific rule)
      
      all data needed accessible through global statement, eg global $vtprd_cart, $vtprd_rules_set, $vtprd_rule, $vtprd_info, $vtprd_setup_options;
        Rule ID = $vtprd_rules_set[$i]->post_id
       filter can check for specific rule_id, and apply criteria.
         if failed additional criteria check, return FALSE, so that the rule is not executed 
      To Execute, sample:
            add_filter('vtprd_additional_inpop_include_criteria', 'your function name', 10, 3);
	          add_filter('vtprd_additional_inpop_actionpop_criteria', 'your function name', 10, 3);
            
        $i = ruleset occurrence ($vtprd_rules_set[$i])
        $k = cart occurence  ($vtprd_cart->cart_items[$k])