Support for fetching agreement

src/Message/RestFetchAgreementRequest.php

@@ -0,0 +1,75 @@
+<?php
+/**
+ * PayPal REST Fetch Transaction Request
+ */
+
+namespace Omnipay\PayPal\Message;
+
+/**
+ * PayPal REST Fetch Agreement Request
+ *
+ * To get details of Agreement created by a create subscription request, PayPal provides the /billing-agreements
+ *
+ * Example -- note this example assumes that the subscription creation request has been successful
+ * and that there is already an agreement recorded in Paypal
+ *
+ * <code>
+ *   // Fetch the transaction so that details can be found for refund, etc.
+ *   $transaction = $gateway->fetchAgreement();
+ *   $transaction->setAgreementId($agreementId);
+ *   $response = $transaction->send();
+ *   $data = $response->getData();
+ *   echo "Gateway fetchAgreement response data == " . print_r($data, true) . "\n";
+ * </code>
+ *
+ * @see RestCreateSubscriptionRequest
+ * @see Omnipay\PayPal\RestGateway
+ * @link https://developer.paypal.com/docs/api/payments.billing-agreements#agreement_get
+ */
+class RestFetchAgreementRequest extends AbstractRestRequest
+{
+    public function getData()
+    {
+        $this->validate('agreementId');
+        return array();
+    }
+
+    /**
+     * Get the agreement id
+     *
+     * @return mixed
+     */
+    public function getAgreementId()
+    {
+        return $this->getParameter('agreementId');
+    }
+
+    /**
+     * Set the agreement id
+     *
+     * @param $value
+     * @return \Omnipay\Common\Message\AbstractRequest
+     */
+    public function setAgreementId($value)
+    {
+        return $this->setParameter('agreementId', $value);
+    }
+
+    /**
+     * Get HTTP Method.
+     *
+     * The HTTP method for fetchTransaction requests must be GET.
+     * Using POST results in an error 500 from PayPal.
+     *
+     * @return string
+     */
+    protected function getHttpMethod()
+    {
+        return 'GET';
+    }
+
+    public function getEndpoint()
+    {
+        return parent::getEndpoint() . '/payments/billing-agreement/' . $this->getAgreementId();
+    }
+}

src/RestGateway.php

@@ -723,6 +723,20 @@ public function searchTransaction(array $parameters = array())
         return $this->createRequest('\Omnipay\PayPal\Message\RestSearchTransactionRequest', $parameters);
     }
 
+    /**
+     * Retrieve an agreement
+     *
+     * Use this call to fetch agreement details
+     *
+     * @link https://developer.paypal.com/docs/api/payments.billing-agreements#agreement_get
+     * @param array $parameters
+     * @return Message\AbstractRestRequest
+     */
+    public function fetchAgreement(array $parameters = array())
+    {
+        return $this->createRequest('\Omnipay\PayPal\Message\RestFetchAgreementRequest', $parameters);
+    }
+
     /**
      * @param array $parameters
      *
@@ -744,7 +758,6 @@ public function verifyWebhookSignature(array $parameters = [])
     }
 
     // TODO: Update an agreement
-    // TODO: Retrieve an agreement
     // TODO: Set outstanding agreement amounts
     // TODO: Bill outstanding agreement amounts
 }