Merge application response headers

- Compose the application response into the SendApiProblemResponseListener when
  it is an HTTP response.
- When calling `sendHeaders()`, merge in the application response headers into
  the ApiProblemResponse headers to ensure things such as CORS support will
  function.

Author: weierophinney

composer.json

@@ -28,6 +28,7 @@
     "require": {
         "php": ">=5.3.23",
         "zendframework/zend-eventmanager": "~2.3",
+        "zendframework/zend-http": "~2.3",
         "zendframework/zend-json": "~2.3",
         "zendframework/zend-mvc": "~2.3",
         "zendframework/zend-view": "~2.3"
@@ -37,7 +38,6 @@
         "phpunit/PHPUnit": "3.7.*",
         "satooshi/php-coveralls": ">=0.6.0",
         "zendframework/zend-console": "~2.3",
-        "zendframework/zend-http": "~2.3",
         "zendframework/zend-loader": "~2.3"
     },
     "autoload": {

src/Factory/SendApiProblemResponseListenerFactory.php

@@ -6,6 +6,7 @@
 
 namespace ZF\ApiProblem\Factory;
 
+use Zend\Http\Response as HttpResponse;
 use Zend\ServiceManager\FactoryInterface;
 use Zend\ServiceManager\ServiceLocatorInterface;
 use ZF\ApiProblem\Listener\SendApiProblemResponseListener;
@@ -26,6 +27,13 @@ public function createService(ServiceLocatorInterface $serviceLocator)
         $listener = new SendApiProblemResponseListener();
         $listener->setDisplayExceptions($displayExceptions);
 
+        if ($serviceLocator->has('Response')) {
+            $response = $serviceLocator->get('Response');
+            if ($response instanceof HttpResponse) {
+                $listener->setApplicationResponse($response);
+            }
+        }
+
         return $listener;
     }
 }

src/Listener/SendApiProblemResponseListener.php

@@ -6,6 +6,7 @@
 
 namespace ZF\ApiProblem\Listener;
 
+use Zend\Http\Response as HttpResponse;
 use Zend\Mvc\ResponseSender\HttpResponseSender;
 use Zend\Mvc\ResponseSender\SendResponseEvent;
 use ZF\ApiProblem\ApiProblemResponse;
@@ -15,11 +16,26 @@
  */
 class SendApiProblemResponseListener extends HttpResponseSender
 {
+    /**
+     * @var HttpResponse;
+     */
+    protected $applicationResponse;
+
     /**
      * @var bool
      */
     protected $displayExceptions = false;
 
+    /**
+     * @param  HttpResponse $response
+     * @return self
+     */
+    public function setApplicationResponse(HttpResponse $response)
+    {
+        $this->applicationResponse = $response;
+        return $this;
+    }
+
     /**
      * Set the flag determining whether exception stack traces are included
      *
@@ -61,6 +77,29 @@ public function sendContent(SendResponseEvent $e)
         return parent::sendContent($e);
     }
 
+    /**
+     * Send HTTP response headers
+     *
+     * If an application response is composed, and is an HTTP response, merges
+     * its headers with the ApiProblemResponse headers prior to sending them.
+     *
+     * @param  SendResponseEvent $e
+     * @return self
+     */
+    public function sendHeaders(SendResponseEvent $e)
+    {
+        $response = $e->getResponse();
+        if (!$response instanceof ApiProblemResponse) {
+            return $this;
+        }
+
+        if ($this->applicationResponse instanceof HttpResponse) {
+            $this->mergeHeaders($this->applicationResponse, $response);
+        }
+
+        return parent::sendHeaders($e);
+    }
+
     /**
      * Send ApiProblem response
      *
@@ -79,4 +118,21 @@ public function __invoke(SendResponseEvent $event)
         $event->stopPropagation(true);
         return $this;
     }
+
+    /**
+     * Merge headers set on the application response into the API Problem response
+     *
+     * @param  HttpResponse $applicationResponse
+     * @param  ApiProblemResponse $apiProblemResponse
+     */
+    protected function mergeHeaders(HttpResponse $applicationResponse, ApiProblemResponse $apiProblemResponse)
+    {
+        $apiProblemHeaders = $apiProblemResponse->getHeaders();
+        foreach ($applicationResponse->getHeaders() as $header) {
+            if ($apiProblemHeaders->has($header->getFieldName())) {
+                continue;
+            }
+            $apiProblemHeaders->addHeader($header);
+        }
+    }
 }

test/Listener/SendApiProblemResponseListenerTest.php

@@ -81,4 +81,20 @@ public function testSendContentDoesNothingIfEventDoesNotContainApiProblemRespons
         $this->assertInternalType('string', $contents);
         $this->assertEmpty($contents);
     }
+
+    public function testSendHeadersMergesApplicationAndProblemHttpHeaders()
+    {
+        $appResponse = new HttpResponse();
+        $appResponse->getHeaders()->addHeaderLine('Access-Control-Allow-Origin', '*');
+
+        $listener = new SendApiProblemResponseListener();
+        $listener->setApplicationResponse($appResponse);
+
+        ob_start();
+        $listener->sendHeaders($this->event);
+        ob_get_clean();
+
+        $headers = $this->response->getHeaders();
+        $this->assertTrue($headers->has('Access-Control-Allow-Origin'));
+    }
 }