clean install

web/modules/consumers/src/EventSubscriber/ConsumerVaryEventSubscriber.php

@@ -0,0 +1,75 @@
+<?php
+
+namespace Drupal\consumers\EventSubscriber;
+
+use Drupal\consumers\MissingConsumer;
+use Drupal\consumers\Negotiator;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+use Symfony\Component\HttpKernel\Event\ResponseEvent;
+use Symfony\Component\HttpKernel\KernelEvents;
+
+/**
+ * Vary header by consumer.
+ */
+class ConsumerVaryEventSubscriber implements EventSubscriberInterface {
+
+  /**
+   * The consumer id header key.
+   *
+   * @var string
+   */
+  const CONSUMER_ID_HEADER = 'X-Consumer-ID';
+
+  /**
+   * The consumer negotiator.
+   *
+   * @var \Drupal\consumers\Negotiator
+   */
+  protected $negotiator;
+
+  /**
+   * ConsumerVaryEventSubscriber constructor.
+   *
+   * @param \Drupal\consumers\Negotiator $negotiator
+   *   The consumer negotiator.
+   */
+  public function __construct(Negotiator $negotiator) {
+    $this->negotiator = $negotiator;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents() {
+    return [
+      KernelEvents::RESPONSE => 'onRespond',
+    ];
+  }
+
+  /**
+   * React on response and set the Vary header.
+   */
+  public function onRespond(ResponseEvent $event) {
+    $response = $event->getResponse();
+
+    try {
+      $consumer = $this->negotiator->negotiateFromRequest($event->getRequest());
+    }
+    catch (MissingConsumer $e) {
+      // If there's no consumer in the header, and no default consumer then we
+      // don't need to add any Vary headers.
+      $consumer = FALSE;
+    }
+
+    if ($consumer) {
+      // Add consumer id to headers.
+      $response->headers->set(self::CONSUMER_ID_HEADER, $consumer->getClientId());
+
+      // Add consumer id to vary headers.
+      $vary_headers = $response->getVary();
+      $vary_headers[] = self::CONSUMER_ID_HEADER;
+      $response->setVary($vary_headers);
+    }
+  }
+
+}