MagentoOneStepCoupon.php

public function couponPostAction()
    {
        /**
         * No reason continue with empty shopping cart
         */
       
        if ($this->_expireAjax()) {
            return;
        }
 
        $couponCode = (string) $this->getRequest()->getParam('coupon_code');
        if ($remov=$this->getRequest()->getParam('remove') == 1) {
            $couponCode = '';
        }
         //$result['enabled']=false;
        $oldCouponCode = $this->_getQuote()->getCouponCode();
 
        if (!strlen($couponCode) && !strlen($oldCouponCode)) {
           $result['enabled']=false;
            return;
        }
       
        /**
         * Gift Certificate Change
         */
 
        $cert = Mage::getModel('ugiftcert/cert')->load($couponCode, 'cert_number');
 
        try {
            if ($cert->getId()){
               if($cert->getStatus()=='A' && $cert->getBalance()>0) {
                    $quote = $this->_getQuote();
                    $cert->addToQuote($quote);
                    $quote->collectTotals()->save();
                   
                    // success return
                    $result['success'] = $this->__("Gift certificate '%s' was applied to your order.", Mage::helper('core')->htmlEscape($cert->getCertNumber()));
                    $result['reload']=true;
               } else {
                    // fail return
                    $result['error'] = $this->__('Coupon code "%s" is not valid.', Mage::helper('core')->htmlEscape($cert->getCertNumber()));
                    $result['reload']=true;                  
               }
            } else {
                $this->_getQuote()->getShippingAddress()->setCollectShippingRates(true);
                $this->_getQuote()->setCouponCode(strlen($couponCode) ? $couponCode : '')
                 ->collectTotals()
                 ->save();  
            }
 
            if ($couponCode) {
                if(!$cert->getId()){
                    if ($couponCode == $this->_getQuote()->getCouponCode()) {
                        $result['success'] = $this->__('Coupon code "%s" was applied successfully.', Mage::helper('core')->htmlEscape($couponCode));
                        $result['reload']=true;
                    }
                    else {
 
                       $result['error'] =$this->__('Coupon code "%s" is not valid.', Mage::helper('core')->htmlEscape($couponCode));
                       $result['reload']=false;
                    }
               }
            } else {
                $result['error'] = $this->__('Coupon code was canceled successfully.');
               $result['reload']=true;
            }
 
        }
        catch (Mage_Core_Exception $e) {
             $result['error'] = $e->getMessage();
        }
        catch (Exception $e) {
           
            $result['error'] = $this->__('Can not apply coupon code.');
        }
        $this->getResponse()->setBody(Zend_Json::encode($result));
                return;
    }