Return latest revision of content

Closes #3446883

Contains refactored contrib from @bstan

src/Plugin/GraphQL/DataProducer/EntityLoadRevision.php

+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\graphql_compose\Plugin\GraphQL\DataProducer;
+
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Drupal\Core\Entity\RevisionableInterface;
+use Drupal\Core\Entity\TranslatableInterface;
+use Drupal\Core\Entity\TranslatableRevisionableStorageInterface;
+use Drupal\Core\Language\LanguageManagerInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\graphql\GraphQL\Buffers\EntityRevisionBuffer;
+use Drupal\graphql\GraphQL\Execution\FieldContext;
+use Drupal\graphql\Plugin\GraphQL\DataProducer\DataProducerPluginBase;
+use GraphQL\Deferred;
+use GraphQL\Error\UserError;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Loads the entity by revision.
+ *
+ * @DataProducer(
+ *   id = "entity_load_revision",
+ *   name = @Translation("Load entity revision"),
+ *   description = @Translation("The entity belonging to the current url."),
+ *   produces = @ContextDefinition("entity",
+ *     label = @Translation("Entity"),
+ *   ),
+ *   consumes = {
+ *     "entity" = @ContextDefinition("any",
+ *       label = @Translation("The entity to load revisions from"),
+ *     ),
+ *     "identifier" = @ContextDefinition("any",
+ *       label = @Translation("Revision ID"),
+ *       required = FALSE,
+ *     ),
+ *     "language" = @ContextDefinition("string",
+ *       label = @Translation("Language code"),
+ *       required = FALSE,
+ *     ),
+ *   },
+ * )
+ */
+class EntityLoadRevision extends DataProducerPluginBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * The latest revision identifiers.
+   */
+  const REVISION_LATEST = [
+    'latest',
+    'newest',
+    'working',
+    'working-copy',
+  ];
+
+  /**
+   * The current revision identifiers.
+   */
+  const REVISION_CURRENT = [
+    'active',
+    'current',
+    'default',
+  ];
+
+  /**
+   * Constructs a \Drupal\Component\Plugin\PluginBase object.
+   *
+   * @param array $configuration
+   *   The plugin configuration array.
+   * @param string $pluginId
+   *   The plugin id.
+   * @param mixed $pluginDefinition
+   *   The plugin definition array.
+   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entityTypeManager
+   *   The language manager service.
+   * @param \Drupal\graphql\GraphQL\Buffers\EntityRevisionBuffer $entityRevisionBuffer
+   *   The entity revision buffer service.
+   * @param \Drupal\Core\Language\LanguageManagerInterface $languageManager
+   *   The language manager service.
+   */
+  public function __construct(
+    array $configuration,
+    $pluginId,
+    $pluginDefinition,
+    protected EntityTypeManagerInterface $entityTypeManager,
+    protected EntityRevisionBuffer $entityRevisionBuffer,
+    protected LanguageManagerInterface $languageManager,
+  ) {
+    parent::__construct($configuration, $pluginId, $pluginDefinition);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $container->get('entity_type.manager'),
+      $container->get('graphql.buffer.entity_revision'),
+      $container->get('language_manager'),
+    );
+  }
+
+  /**
+   * Resolve the entity revision.
+   *
+   * @param \Drupal\Core\Entity\EntityInterface|null $entity
+   *   The entity to load revisions from.
+   * @param int|string|null $identifier
+   *   The revision ID to load.
+   * @param string|null $language
+   *   The language code to use.
+   * @param \Drupal\graphql\GraphQL\Execution\FieldContext $context
+   *   Cache context.
+   */
+  public function resolve(?EntityInterface $entity, int|string|null $identifier, ?string $language, FieldContext $context): Deferred|EntityInterface|null {
+
+    $identifier = $identifier ? strtolower((string) $identifier) : NULL;
+
+    if (!$identifier || in_array($identifier, self::REVISION_CURRENT)) {
+      return $entity;
+    }
+
+    if (!$entity instanceof RevisionableInterface) {
+      return $entity;
+    };
+
+    $entity_id = $entity->id();
+    $entity_type_id = $entity->getEntityTypeId();
+
+    // We need a langcode for getLatestTranslationAffectedRevisionId().
+    // Set the default langcode to the current context language.
+    // Fall back to the current language.
+    $langcode = $language
+      ?: $context->getContextLanguage()
+      ?: $this->languageManager->getCurrentLanguage()->getId();
+
+    // Quickly resolve the latest revision.
+    if (in_array($identifier, self::REVISION_LATEST)) {
+      /** @var \Drupal\Core\Entity\RevisionableStorageInterface $storage */
+      $storage = $this->entityTypeManager->getStorage($entity_type_id);
+
+      $identifier = ($storage instanceof TranslatableRevisionableStorageInterface)
+        ? $storage->getLatestTranslationAffectedRevisionId($entity_id, $langcode)
+        : $storage->getLatestRevisionId($entity_id);
+
+      // Did not get a valid revision identifier.
+      if (!$identifier) {
+        return NULL;
+      }
+    }
+
+    // Add the entity to the buffer.
+    $resolver = $this->entityRevisionBuffer->add($entity_type_id, $identifier);
+
+    return new Deferred(function () use ($resolver, $langcode, $entity_id, $entity_type_id, $context) {
+
+      /** @var \Drupal\Core\Entity\RevisionableInterface|null $revision */
+      if (!$revision = $resolver()) {
+        // Add cache list tags to invalidate the cache.
+        $entity_type = $this->entityTypeManager->getDefinition($entity_type_id, FALSE);
+        if ($entity_type) {
+          $context->addCacheTags($entity_type->getListCacheTags());
+        }
+
+        $context->addCacheTags(['4xx-response']);
+        return NULL;
+      }
+
+      // Check the revision belongs to the entity.
+      if ($revision->id() !== $entity_id) {
+        throw new UserError('The requested revision does not belong to the requested entity.');
+      }
+
+      $context->setContextValue('revision', $revision->getRevisionId());
+
+      // A specific language was requested.
+      // Ensure the revision is translated.
+      if ($langcode && $revision instanceof TranslatableInterface && $revision->hasTranslation($langcode) && $langcode !== $revision->language()->getId()) {
+        $revision = $revision->getTranslation($langcode);
+        $revision->addCacheContexts(["static:language:{$langcode}"]);
+      }
+
+      // Check revision access.
+      $access = $revision->access('view', NULL, TRUE);
+      $context->addCacheableDependency($access);
+
+      return $access->isAllowed() ? $revision : NULL;
+    });
+  }
+
+}