public function findMissingProducts()
 {
     $items = WPLA_ListingQueryHelper::findMissingProducts();
     $mode = isset($_REQUEST['mode']) ? $_REQUEST['mode'] : false;
     if ($mode == 'delete') {
         foreach ($items as $item) {
             WPLA_ListingsModel::deleteItem($item->id);
         }
         wpla_show_message(sizeof($items) . ' items have been deleted.');
         return;
     }
     if ($mode == 'import') {
         foreach ($items as $item) {
             $data = array('status' => 'imported');
             WPLA_ListingsModel::updateWhere(array('id' => $item->id), $data);
         }
         wpla_show_message(sizeof($items) . ' items have been added to the import queue.');
         return;
     }
     if (!empty($items)) {
         $nonce = wp_create_nonce('wpla_tools_page');
         $btn_delete = '<a href="admin.php?page=wpla-tools&tab=inventory&action=wpla_check_for_missing_products&mode=delete&_wpnonce=' . $nonce . '" class="button button-small button-secondary">' . 'Delete all from DB' . '</a> &nbsp; ';
         $btn_import = '<a href="admin.php?page=wpla-tools&tab=inventory&action=wpla_check_for_missing_products&mode=import&_wpnonce=' . $nonce . '" class="button button-small button-primary"  >' . 'Add to import queue' . '</a>';
         $buttons = ' &nbsp; ' . $btn_delete . $btn_import;
         wpla_show_message('There are ' . sizeof($items) . ' listing(s) without a linked product in WooCommerce.' . $buttons, 'error');
     } else {
         wpla_show_message('No missing products found.');
     }
 }