component_library-1.0.x-dev/src/EventSubscriber/EntityFieldYamlPlaceholders.php

<?php

declare(strict_types=1);

namespace Drupal\component_library\EventSubscriber;

use Drupal\component_library\Event\ConvertYamlPlaceholdersEvent;
use Drupal\Core\Cache\CacheableMetadata;
use Drupal\Core\Entity\ContentEntityInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;

final class EntityFieldYamlPlaceholders implements EventSubscriberInterface {

  public static function getSubscribedEvents(): array {
    return [
      ConvertYamlPlaceholdersEvent::class => ['onConvertYamlPlaceholders'],
    ];
  }

  public function onConvertYamlPlaceholders(ConvertYamlPlaceholdersEvent $event): void {
    $context = $event->getContext();
    foreach ($context as $key => $value) {
      if (\is_string($value) && \str_starts_with($value, 'field:')) {
        $values = \explode(':', $value);
        if (\count($values) !== 3) {
          // This isn't a field, so don't set the context item.
          continue;
        }
        [, $context_id, $field_name] = $values;
        if (!\array_key_exists($context_id, $context) || !$context[$context_id] instanceof ContentEntityInterface) {
          $event->setContextItem($key, []);
          continue;
        }
        $entity = $context[$context_id];
        $entity_access = $entity->access('view', NULL, TRUE);
        if (!$entity_access->isAllowed()) {
          $event->setContextItem($key, []);
          continue;
        }
        if (!$entity->hasField($field_name)) {
          $event->setContextItem($key, []);
          continue;
        }
        $field_access = $entity->get($field_name)->access('view', NULL, TRUE);
        if (!$field_access->isAllowed()) {
          $event->setContextItem($key, []);
          continue;
        }
        $build = $entity->get($field_name)->view($event->getViewMode());
        CacheableMetadata::createFromRenderArray($build)
          ->merge(CacheableMetadata::createFromObject($field_access))
          ->merge(CacheableMetadata::createFromObject($entity_access))
          ->merge(CacheableMetadata::createFromObject($entity))
          ->applyTo($build);
        $event->setContextItem($key, $build);
      }
    }
  }

}