buy x items get the cheapest for free

[fruchtge]

Hi, I like to have the option buy x items get the cheapest for free in my shop. I like to change the $products_price variable in function calculate() und function get_products() of includes/classes/shopping_cart.php with this code (now it is basic and just an idea)

 

 if ( ($this->count_contents() > 3) && ($products_id == $this->cheapestproduct())) { $products_price = '0'; }

 

my Problem is to get the cheapest item in cart, my function cheapestproduct() does not work:

 

   function cheapestproduct() {

     if (is_array($this->contents)) {
       reset($this->contents);
       while (list($products_id, ) = each($this->contents)) {


         $product_special_query = tep_db_query("select products_id, products_price from " . TABLE_PRODUCTS . " where products_id = '" . (int)$products_id . "'");
         if ($product_special = tep_db_fetch_array($product_special_query)) {
           $pr_special_id = $product_special['products_id'];
           $products_special_price = $product_special['products_price'];

           $specials_special_query = tep_db_query("select specials_new_products_price from " . TABLE_SPECIALS . " where products_id = '" . (int)$prid . "' and status = '1'");
           if (tep_db_num_rows ($specials_special_query)) {
             $specials_special = tep_db_fetch_array($specials_special_query);
             $products_special_price = $specials_special['specials_new_products_price'];
           }
//            $this->total += $currencies->calculate_price($products_price, $products_tax, $qty);
//            $this->weight += ($qty * $products_weight);
         }

         if (tep_not_null($cheapestproduct)) {
           if ($products_special_price < $cheapestprice) {
             $cheapestproduct = $products_id;
             $cheapestprice = $products_special_price;
           } else {

           }

         } else {
         $cheapestproduct = $products_id;
         $cheapestprice = $products_special_price;
         }
       }
     }
     return $cheapestproduct;
   }

 

Maybe someone could help.