class WorkspacePublisher

class WorkspacePublisher implements WorkspacePublisherInterface {
    use StringTranslationTrait;
    public function __construct(EntityTypeManagerInterface $entityTypeManager, Connection $database, WorkspaceManagerInterface $workspaceManager, WorkspaceAssociationInterface $workspaceAssociation, EventDispatcherInterface $eventDispatcher, WorkspaceInterface $sourceWorkspace, LoggerInterface $logger) {
    }
    
    /**
     * {@inheritdoc}
     */
    public function publish() {
        if ($this->sourceWorkspace
            ->hasParent()) {
            throw new WorkspacePublishException('Only top-level workspaces can be published.');
        }
        if ($this->checkConflictsOnTarget()) {
            throw new WorkspaceConflictException();
        }
        $tracked_entities = $this->workspaceAssociation
            ->getTrackedEntities($this->sourceWorkspace
            ->id());
        $event = new WorkspacePrePublishEvent($this->sourceWorkspace, $tracked_entities);
        $this->eventDispatcher
            ->dispatch($event);
        if ($event->isPublishingStopped()) {
            throw new WorkspacePublishException((string) $event->getPublishingStoppedReason());
        }
        try {
            $transaction = $this->database
                ->startTransaction();
            // @todo Handle the publishing of a workspace with a batch operation in
            //   https://www.drupal.org/node/2958752.
            $this->workspaceManager
                ->executeOutsideWorkspace(function () use ($tracked_entities) {
                foreach ($tracked_entities as $entity_type_id => $revision_difference) {
                    $entity_revisions = $this->entityTypeManager
                        ->getStorage($entity_type_id)
                        ->loadMultipleRevisions(array_keys($revision_difference));
                    $default_revisions = $this->entityTypeManager
                        ->getStorage($entity_type_id)
                        ->loadMultiple(array_values($revision_difference));
                    
                    /** @var \Drupal\Core\Entity\ContentEntityInterface $entity */
                    foreach ($entity_revisions as $entity) {
                        // When pushing workspace-specific revisions to the default
                        // workspace (Live), we simply need to mark them as default
                        // revisions.
                        $entity->setSyncing(TRUE);
                        $entity->isDefaultRevision(TRUE);
                        // The default revision is not workspace-specific anymore.
                        $field_name = $entity->getEntityType()
                            ->getRevisionMetadataKey('workspace');
                        $entity->{$field_name}->target_id = NULL;
                        $entity->original = $default_revisions[$entity->id()];
                        $entity->save();
                    }
                }
            });
        } catch (\Exception $e) {
            if (isset($transaction)) {
                $transaction->rollBack();
            }
            Error::logException($this->logger, $e);
            throw $e;
        }
        $event = new WorkspacePostPublishEvent($this->sourceWorkspace, $tracked_entities);
        $this->eventDispatcher
            ->dispatch($event);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getSourceLabel() {
        return $this->sourceWorkspace
            ->label();
    }
    
    /**
     * {@inheritdoc}
     */
    public function getTargetLabel() {
        return $this->t('Live');
    }
    
    /**
     * {@inheritdoc}
     */
    public function checkConflictsOnTarget() {
        // Nothing to do for now, we can not get to a conflicting state because an
        // entity which is being edited in a workspace can not be edited in any
        // other workspace.
    }
    
    /**
     * {@inheritdoc}
     */
    public function getDifferringRevisionIdsOnTarget() {
        $target_revision_difference = [];
        $tracked_entities = $this->workspaceAssociation
            ->getTrackedEntities($this->sourceWorkspace
            ->id());
        foreach ($tracked_entities as $entity_type_id => $tracked_revisions) {
            $entity_type = $this->entityTypeManager
                ->getDefinition($entity_type_id);
            // Get the latest revision IDs for all the entities that are tracked by
            // the source workspace.
            $query = $this->entityTypeManager
                ->getStorage($entity_type_id)
                ->getQuery()
                ->accessCheck(FALSE)
                ->condition($entity_type->getKey('id'), $tracked_revisions, 'IN')
                ->latestRevision();
            $result = $query->execute();
            // Now we compare the revision IDs which are tracked by the source
            // workspace to the latest revision IDs of those entities and the
            // difference between these two arrays gives us all the entities which
            // have been modified on the target.
            if ($revision_difference = array_diff_key($result, $tracked_revisions)) {
                $target_revision_difference[$entity_type_id] = $revision_difference;
            }
        }
        return $target_revision_difference;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getDifferringRevisionIdsOnSource() {
        // Get the Workspace association revisions which haven't been pushed yet.
        return $this->workspaceAssociation
            ->getTrackedEntities($this->sourceWorkspace
            ->id());
    }
    
    /**
     * {@inheritdoc}
     */
    public function getNumberOfChangesOnTarget() {
        $total_changes = $this->getDifferringRevisionIdsOnTarget();
        return count($total_changes, COUNT_RECURSIVE) - count($total_changes);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getNumberOfChangesOnSource() {
        $total_changes = $this->getDifferringRevisionIdsOnSource();
        return count($total_changes, COUNT_RECURSIVE) - count($total_changes);
    }

}