class WorkspaceSubscriber

class WorkspaceSubscriber implements EventSubscriberInterface {
    
    /**
     * Constructs a new WorkspaceSubscriber instance.
     *
     * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entityTypeManager
     *   The entity type manager service.
     * @param \Drupal\workspaces\WorkspaceAssociationInterface|null $workspaceAssociation
     *   The workspace association service.
     */
    public function __construct(EntityTypeManagerInterface $entityTypeManager, ?WorkspaceAssociationInterface $workspaceAssociation) {
    }
    
    /**
     * Prevents a workspace from being published based on certain conditions.
     *
     * @param \Drupal\workspaces\Event\WorkspacePublishEvent $event
     *   The workspace publish event.
     */
    public function onWorkspacePrePublish(WorkspacePublishEvent $event) : void {
        // Prevent a workspace from being published if there are any pending
        // revisions in a moderation state that doesn't create default revisions.
        $workspace = $event->getWorkspace();
        $tracked_revisions = $this->workspaceAssociation
            ->getTrackedEntities($workspace->id());
        // Gather a list of moderation states that don't create a default revision.
        $workflow_non_default_states = [];
        foreach ($this->entityTypeManager
            ->getStorage('workflow')
            ->loadByProperties([
            'type' => 'content_moderation',
        ]) as $workflow) {
            
            /** @var \Drupal\content_moderation\Plugin\WorkflowType\ContentModerationInterface $workflow_type */
            $workflow_type = $workflow->getTypePlugin();
            // Find all workflows which are moderating entity types of the same type
            // to those that are tracked by the workspace.
            if (array_intersect($workflow_type->getEntityTypes(), array_keys($tracked_revisions))) {
                $workflow_non_default_states[$workflow->id()] = array_filter(array_map(function (ContentModerationState $state) {
                    return !$state->isDefaultRevisionState() ? $state->id() : NULL;
                }, $workflow_type->getStates()));
            }
        }
        // If no tracked revisions are moderated then no status check is necessary.
        if (empty($workflow_non_default_states)) {
            return;
        }
        // Check if any revisions that are about to be published are in a
        // non-default revision moderation state.
        $query = $this->entityTypeManager
            ->getStorage('content_moderation_state')
            ->getQuery()
            ->allRevisions()
            ->accessCheck(FALSE);
        $tracked_revisions_condition_group = $query->orConditionGroup();
        foreach ($tracked_revisions as $tracked_type => $tracked_revision_ids) {
            $entity_type_group = $query->andConditionGroup()
                ->condition('content_entity_type_id', $tracked_type)
                ->condition('content_entity_revision_id', array_keys($tracked_revision_ids), 'IN');
            $tracked_revisions_condition_group->condition($entity_type_group);
        }
        $query->condition($tracked_revisions_condition_group);
        $workflow_condition_group = $query->orConditionGroup();
        foreach ($workflow_non_default_states as $workflow_id => $non_default_states) {
            $group = $query->andConditionGroup()
                ->condition('workflow', $workflow_id, '=')
                ->condition('moderation_state', $non_default_states, 'IN');
            $workflow_condition_group->condition($group);
        }
        $query->condition($workflow_condition_group);
        if ($count = $query->count()
            ->execute()) {
            $message = \Drupal::translation()->formatPlural($count, 'The @label workspace can not be published because it contains 1 item in an unpublished moderation state.', 'The @label workspace can not be published because it contains @count items in an unpublished moderation state.', [
                '@label' => $workspace->label(),
            ]);
            $event->stopPublishing();
            $event->setPublishingStoppedReason((string) $message);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public static function getSubscribedEvents() : array {
        $events[WorkspacePrePublishEvent::class][] = [
            'onWorkspacePrePublish',
        ];
        return $events;
    }

}