How to load coupon details via API

<?php
include 'PapApi.class.php'; //the PapApi.class.php can be found at the PAP installation folder, in the 'api' directory 

$session = new Pap_Api_Session("https://your_pap_url/scripts/server.php");
if(!$session->login("merchant login","password")) {
    die("Cannot login. Message: ". $session->getMessage());
}

$couponCode = 'xxxxxx';
$request = new Gpf_Rpc_FormRequest("Pap_Features_Coupon_OfflineSaleForm", "load", $session); 
$request->setField('Id', $couponCode); 
try { 
    $request->sendNow();
} catch(Exception $e) {
    die("API call error: ".$e->getMessage()); 
}

$responseForm = $request->getForm();

if($responseForm->isSuccessful() && $responseForm->existsField('couponcode') && $responseForm->getFieldValue('couponcode') != null) {
    echo 'Coupon is valid.';
    echo '<br>'; 
    echo 'Coupon code: '.$responseForm->getFieldValue('couponcode'); 
    echo '<br>';
    echo 'Coupon name:'.$responseForm->getFieldValue('name'); 
    echo '<br>';
    echo 'Coupon description: '.$responseForm->getFieldValue('description');
    echo '<br>';
    echo 'Banner description: '.$responseForm->getFieldValue('bannerDescription');
    echo '<br>';
    $userRecord = $responseForm->getFields()->getRecord('userid'); 

    $affiliateValues = $userRecord->get(Gpf_Rpc_Form::FIELD_VALUES); 
    $affiliateValuesNames = array_flip($affiliateValues[0]); 
    echo 'User ID: '.$affiliateValues[1][$affiliateValuesNames['userid']];
    echo '<br>'; 
    echo 'User login name: '.$affiliateValues[1][$affiliateValuesNames['username']];
    echo '<br>'; 
    echo 'User firstname: '.$affiliateValues[1][$affiliateValuesNames['firstname']];
    echo '<br>'; 
    echo 'User lastname: '.$affiliateValues[1][$affiliateValuesNames['lastname']];
    echo '<br>'; 
} else {
    echo 'Coupon is invalid.';
}
?>