Merge pull request #920 from rosiel/infinite-derivs

Avoid Infinite Derivatives.

src/EventGenerator/EmitEvent.php

@@ -14,6 +14,7 @@
 use Drupal\Core\StringTranslation\StringTranslationTrait;
 use Drupal\islandora\Event\StompHeaderEvent;
 use Drupal\islandora\Event\StompHeaderEventException;
+use Drupal\islandora\Exception\IslandoraDerivativeException;
 use Stomp\Exception\StompException;
 use Stomp\StatefulStomp;
 use Stomp\Transport\Message;
@@ -168,6 +169,10 @@ public function execute($entity = NULL) {
         $event->getHeaders()->all()
       );
     }
+    catch (IslandoraDerivativeException $e) {
+      $this->logger->info($e->getMessage());
+      return;
+    }
     catch (StompHeaderEventException $e) {
       $this->logger->error($e->getMessage());
       $this->messenger->addError($e->getMessage());

src/Exception/IslandoraDerivativeException.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace Drupal\islandora\Exception;
+
+/**
+ * Islandora exceptions.
+ *
+ * @package islandora
+ */
+class IslandoraDerivativeException extends \RuntimeException {
+}

src/Plugin/Action/AbstractGenerateDerivative.php

@@ -5,6 +5,7 @@
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Url;
+use Drupal\islandora\Exception\IslandoraDerivativeException;
 
 /**
  * Emits a Node event.
@@ -60,6 +61,13 @@ protected function generateData(EntityInterface $entity) {
       throw new \RuntimeException("Could not locate taxonomy term with uri: " . $this->configuration['derivative_term_uri'], 500);
     }
 
+    // See if there is a destination media already set, and abort if it's the
+    // same as the source media. Dont cause an error, just don't continue.
+    $derivative_media = $this->utils->getMediaWithTerm($entity, $derivative_term);
+    if (!is_null($derivative_media) && $derivative_media->id() == $source_media->id()) {
+      throw new IslandoraDerivativeException("Halting derivative, as source and target media are the same. Derivative term: [" . $this->configuration['derivative_term_uri'] . "] Source term: [" . $this->configuration['source_term_uri'] . "] Node id: [" . $entity->id() . "].", 500);
+    }
+
     $route_params = [
       'node' => $entity->id(),
       'media_type' => $this->configuration['destination_media_type'],