Put vat description in separate property

Factr.php

@@ -1,6 +1,7 @@
 <?php
 namespace SumoCoders\Factr;
 
+use InvalidArgumentException;
 use SumoCoders\Factr\Exception;
 use SumoCoders\Factr\Client\Client;
 use SumoCoders\Factr\Invoice\Invoice;
@@ -568,7 +569,7 @@ public function invoices(array $filters = null)
                 $filters,
                 function($filter) use ($allowedFilters) {
                     if (!in_array($filter, $allowedFilters)) {
-                        throw new \InvalidArgumentException('Invalid filter');
+                        throw new InvalidArgumentException('Invalid filter');
                     }
                 }
             );
@@ -641,6 +642,11 @@ public function invoicesGetByIid($iid)
      */
     public function invoicesCreate(Invoice $invoice)
     {
+        if (($invoice->getVatException() && !$invoice->getVatDescription())
+            || (!$invoice->getVatException() && $invoice->getVatDescription())) {
+            throw new InvalidArgumentException('Vat exception and vat description are required if one of them is filled');
+        }
+
         $parameters['invoice'] = $invoice->toArray(true);
         $rawData = $this->doCall('invoices.json', $parameters, 'POST');
 

Invoice/Invoice.php

@@ -2,7 +2,6 @@
 namespace SumoCoders\Factr\Invoice;
 
 use SumoCoders\Factr\Client\Client;
-use SumoCoders\Factr\Factr;
 
 /**
  * Class Invoice
@@ -59,7 +58,7 @@ class Invoice
     /**
      * @var string
      */
-    protected $discountDescription, $vatException;
+    protected $discountDescription, $vatException, $vatDescription;
 
     /**
      * @var bool
@@ -423,6 +422,25 @@ public function setVatException($vatException)
         return $this;
     }
 
+    /**
+     * @return string
+     */
+    public function getVatDescription()
+    {
+        return $this->vatDescription;
+    }
+
+    /**
+     * @param string $vatDescription
+     * @return $this
+     */
+    public function setVatDescription($vatDescription)
+    {
+        $this->vatDescription = $vatDescription;
+
+        return $this;
+    }
+
     /**
      * Initialize the object with raw data
      *
@@ -491,9 +509,9 @@ public function toArray($forApi = false)
         }
         if ($this->getVatException()) {
             $data['vat_exception'] = $this->getVatException();
-            if ($this->getVatException() === 'cash_discount') {
-                $data['vat_description'] = 'btw verlegd';
-            }
+        }
+        if ($this->getVatDescription()) {
+            $data['vat_description'] = $this->getVatDescription();
         }
 
         $data['items'] = array();