Calculating parts prices - Symphony CMS

data.parts.php

<?php
public function grab(&$param_pool=NULL){
      $result = new XMLElement($this->dsParamROOTELEMENT);

      try{
              include(TOOLKIT . '/data-sources/datasource.section.php');
      }
      catch(FrontendPageNotFoundException $e){
              // Work around. This ensures the 404 page is displayed and
              // is not picked up by the default catch() statement below
              FrontendPageNotFoundExceptionHandler::render($e);
      }
      catch(Exception $e){
              $result->appendChild(new XMLElement('error', $e->getMessage()));
              return $result;
      }

      if($this->_force_empty_result) $result = $this->emptyXMLSet();

      // Get and set default profit margin
      $dpm_query = 'SELECT value FROM sym_entries_data_1 LIMIT 1';
      $dpm_result = Symphony::Database()->fetch($dpm_query);
      $default_profit_margin = $dpm_result[0]['value'];
      // Add profit margin
      function addProfitMargin($profit_margin, $purchase_price) {
              return (100 + $profit_margin) * $purchase_price / 100;
      }
      // Loop through entries
      foreach($result->getChildren('entry') as $entry) {
              if($entry->getName() == 'entry') {
                      // Loop through entry fields
                      $entry_children = $entry->getChildren();
                      foreach($entry_children as $field) {
                              // Grab entry information required for calculation
                              switch($field->getName()) {
                                      case 'purchase-price':
                                              $purchase_price = $field->getValue();
                                              break;
                                      case 'fixed-sales-price':
                                              $fixed_sales_price = $field->getValue();
                                              break;
                                      case 'custom-profit-margin':
                                              $custom_profit_margin = $field->getValue();
                                              break;
                                      case 'sales-price':
                                              $field_child = $field->getChildrenByName('item');
                                              $sales_price = $field_child[0]->getValue();
                                              break;
                              }
                      }
                      // Calculate actual price
                      switch($sales_price) {
                              case 'Fixed':
                                      $actual_price = $fixed_sales_price;
                                      break;
                              case 'Custom profit margin':
                                      $actual_price = addProfitMargin($custom_profit_margin, $purchase_price);
                                      break;
                              case 'Default profit margin':
                                      $actual_price = addProfitMargin($default_profit_margin, $purchase_price);
                                      break;
                      }
                      // Remove unwanted XML from result
                      $entry->removeChildAt(3);
                      $entry->removeChildAt(4);
                      $entry->removeChildAt(5);
                      // Add actual price to result
                      $entry->appendChild(new XMLElement('price', $actual_price));
              }
      }

      return $result;
}
?>