public function preProcess()
 {
     parent::preProcess();
     //Add or remove product with Ajax
     if (Tools::getValue('ajax') and Tools::getValue('id_product') and Tools::getValue('action')) {
         if (Tools::getValue('action') == 'add') {
             if (isset(self::$cookie->id_customer)) {
                 if (CompareProduct::getCustomerNumberProducts(self::$cookie->id_customer) < Configuration::get('PS_COMPARATOR_MAX_ITEM')) {
                     CompareProduct::addCustomerCompareProduct((int) self::$cookie->id_customer, (int) Tools::getValue('id_product'));
                 } else {
                     die('0');
                 }
             } else {
                 if (isset(self::$cookie->id_guest) and CompareProduct::getGuestNumberProducts(self::$cookie->id_guest) < Configuration::get('PS_COMPARATOR_MAX_ITEM')) {
                     CompareProduct::addGuestCompareProduct((int) self::$cookie->id_guest, (int) Tools::getValue('id_product'));
                 } else {
                     die('0');
                 }
             }
         } elseif (Tools::getValue('action') == 'remove') {
             if (isset(self::$cookie->id_customer)) {
                 CompareProduct::removeCustomerCompareProduct((int) self::$cookie->id_customer, (int) Tools::getValue('id_product'));
             } elseif (isset(self::$cookie->id_guest)) {
                 CompareProduct::removeGuestCompareProduct((int) self::$cookie->id_guest, (int) Tools::getValue('id_product'));
             } else {
                 die('0');
             }
         } else {
             die('0');
         }
         die('1');
     }
 }