Update event API, editing series should reflect in changed date. DDFH…

…ER-132

As we use inheritance, we want an updated series to also reflect in the
updatedAt API property.
We could implement this, by programmatically saving all instances when
the series is saved, but this may have unforseen consequences, as it is
running against the Drupal system.
Instead, we'll look up the instance and series changed dates, and take
which ever is newer.

web/modules/custom/dpl_event/src/Services/EventRestMapper.php

@@ -66,7 +66,7 @@ public function getResponse(EventInstance $event_instance): EventsGET200Response
       'ticketCapacity' => $this->getValue('event_ticket_capacity'),
       'ticketCategories' => $this->getTicketCategories(),
       'createdAt' => $this->getDateField('created'),
-      'updatedAt' => $this->getDateField('changed'),
+      'updatedAt' => $this->getUpdatedDate(),
       'dateTime' => $this->getDate(),
       'externalData' => $this->getExternalData(),
       'series' => new EventsGET200ResponseInnerSeries([
@@ -75,6 +75,37 @@ public function getResponse(EventInstance $event_instance): EventsGET200Response
     ]);
   }
 
+  /**
+   * Getting relevant updated date - either the series or instance.
+   *
+   * As we use inheritance, we want an updated series to also reflect in the
+   * updatedAt API property.
+   * We could implement this, by programmatically saving all instances when
+   * the series is saved, but this may have unforseen consequences, as it is
+   * running against the Drupal system.
+   * Instead, we'll look up the instance and series changed dates, and take
+   * which ever is newer.
+   */
+  private function getUpdatedDate(): ?DateTime {
+    $series = $this->event->getEventSeries();
+
+    $changed_instance = $this->event->getChangedTime();
+    $changed_series = $series->getChangedTime();
+
+    // Setting the timestamp to whichever is the larger.
+    $timestamp = ($changed_instance > $changed_series) ?
+      $changed_instance : $changed_series;
+
+    if (empty($timestamp)) {
+      return NULL;
+    }
+
+    $date = new DateTime();
+    $date->setTimestamp(intval($timestamp));
+
+    return $date;
+  }
+
   /**
    * Getting associated branches.
    *