WIP: Allow for creation of recurring and adhoc subscriptions (#15)

* WIP: Start work on getting subscription billing working

* When creating an adhoc subscription don't pass recurring settings over

* [security] Don't send over the passphrase as part of the request as it allows bad actors to change the amount being billed, etc.

* Reorder and make notes.  Email confirmation needs to be after the custom_xxx items

src/Message/PurchaseRequest.php

@@ -151,6 +151,66 @@ public function setCustomInt5($value)
         return $this->setParameter('customInt5', $value);
     }
 
+    public function getPaymentMethod()
+    {
+        return $this->getParameter('paymentMethod');
+    }
+
+    public function setPaymentMethod($value)
+    {
+        return $this->setParameter('paymentMethod', $value);
+    }
+
+    public function getSubscriptionType()
+    {
+        return $this->getParameter('subscriptionType');
+    }
+
+    public function getBillingDate()
+    {
+        return $this->getParameter('billingDate');
+    }
+
+    public function getRecurringAmount()
+    {
+        return $this->getParameter('recurringAmount');
+    }
+
+    public function getFrequency()
+    {
+        return $this->getParameter('frequency');
+    }
+
+    public function getCycles()
+    {
+        return $this->getParameter('cycles');
+    }
+
+    public function setSubscriptionType($value)
+    {
+        return $this->setParameter('subscriptionType', $value);
+    }
+
+    public function setBillingDate($value)
+    {
+        return $this->setParameter('billingDate', $value);
+    }
+
+    public function setRecurringAmount($value)
+    {
+        return $this->setParameter('recurringAmount', $value);
+    }
+
+    public function setFrequency($value)
+    {
+        return $this->setParameter('frequency', $value);
+    }
+
+    public function setCycles($value)
+    {
+        return $this->setParameter('cycles', $value);
+    }
+
     public function getData()
     {
         $this->validate('amount', 'description');
@@ -182,8 +242,30 @@ public function getData()
         $data['custom_str4'] = $this->getCustomStr4();
         $data['custom_str5'] = $this->getCustomStr5();
 
+        /**
+         * Allow overriding the Payment Method
+         */
+        if ($this->getPaymentMethod()) {
+            $data['payment_method'] = $this->getPaymentMethod();
+        }
+
+        /**
+         * Subscription billing options.
+         */
+        if (1 == $this->getSubscriptionType()) {
+            $data['subscription_type'] = $this->getSubscriptionType();
+            $data['billing_date'] = $this->getBillingDate();
+            $data['recurring_amount'] = $this->getRecurringAmount();
+            $data['frequency'] = $this->getFrequency();
+            $data['cycles'] = $this->getCycles();
+        }
+        if (2 == $this->getSubscriptionType()) {
+            $data['subscription_type'] = $this->getSubscriptionType();
+        }
+
         $data['passphrase'] = $this->getParameter('passphrase');
         $data['signature'] = $this->generateSignature($data);
+        unset($data['passphrase']);
 
         return $data;
     }
@@ -193,11 +275,34 @@ protected function generateSignature($data)
         $fields = array();
 
         // specific order required by PayFast
+        // @see https://developers.payfast.co.za/documentation/#checkout-page
         foreach (array('merchant_id', 'merchant_key', 'return_url', 'cancel_url', 'notify_url', 'name_first',
-                     'name_last', 'email_address', 'm_payment_id', 'amount', 'item_name', 'item_description',
-                     'email_confirmation', 'confirmation_address', 'custom_int1', 'custom_int2', 'custom_int3',
-                     'custom_int4', 'custom_int5', 'custom_str1', 'custom_str2', 'custom_str3', 'custom_str4',
-                     'custom_str5', 'passphrase') as $key) {
+                     'name_last', 'email_address', 'cell_number',
+                    /**
+                     * Transaction Details
+                     */
+                    'm_payment_id', 'amount', 'item_name', 'item_description',
+                    /**
+                     * Custom return data
+                     */
+                    'custom_int1', 'custom_int2', 'custom_int3', 'custom_int4', 'custom_int5',
+                    'custom_str1', 'custom_str2', 'custom_str3', 'custom_str4', 'custom_str5',
+                    /**
+                     * Email confirmation
+                     */
+                    'email_confirmation', 'confirmation_address',
+                    /**
+                     * Payment Method
+                     */
+                    'payment_method',
+                    /**
+                     * Subscriptions
+                     */
+                    'subscription_type', 'billing_date', 'recurring_amount', 'frequency', 'cycles',
+                    /**
+                     * Passphrase for md5 signature generation
+                     */
+                    'passphrase') as $key) {
             if (!empty($data[$key])) {
                 $fields[$key] = $data[$key];
             }