class WorkspaceManager

class WorkspaceManager implements WorkspaceManagerInterface {
    use StringTranslationTrait;
    
    /**
     * An array of entity type IDs that can not belong to a workspace.
     *
     * By default, only entity types which are revisionable and publishable can
     * belong to a workspace.
     *
     * @var string[]
     */
    protected $blacklist = [
        'workspace_association' => 'workspace_association',
        'workspace' => 'workspace',
    ];
    
    /**
     * The request stack.
     *
     * @var \Symfony\Component\HttpFoundation\RequestStack
     */
    protected $requestStack;
    
    /**
     * The entity type manager.
     *
     * @var \Drupal\Core\Entity\EntityTypeManagerInterface
     */
    protected $entityTypeManager;
    
    /**
     * The entity memory cache service.
     *
     * @var \Drupal\Core\Cache\MemoryCache\MemoryCacheInterface
     */
    protected $entityMemoryCache;
    
    /**
     * The current user.
     *
     * @var \Drupal\Core\Session\AccountProxyInterface
     */
    protected $currentUser;
    
    /**
     * The state service.
     *
     * @var \Drupal\Core\State\StateInterface
     */
    protected $state;
    
    /**
     * A logger instance.
     *
     * @var \Psr\Log\LoggerInterface
     */
    protected $logger;
    
    /**
     * The class resolver.
     *
     * @var \Drupal\Core\DependencyInjection\ClassResolverInterface
     */
    protected $classResolver;
    
    /**
     * The workspace association service.
     *
     * @var \Drupal\workspaces\WorkspaceAssociationInterface
     */
    protected $workspaceAssociation;
    
    /**
     * The workspace negotiator service IDs.
     *
     * @var array
     */
    protected $negotiatorIds;
    
    /**
     * The current active workspace or FALSE if there is no active workspace.
     *
     * @var \Drupal\workspaces\WorkspaceInterface|false
     */
    protected $activeWorkspace;
    
    /**
     * Constructs a new WorkspaceManager.
     *
     * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
     *   The request stack.
     * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
     *   The entity type manager.
     * @param \Drupal\Core\Cache\MemoryCache\MemoryCacheInterface $entity_memory_cache
     *   The entity memory cache service.
     * @param \Drupal\Core\Session\AccountProxyInterface $current_user
     *   The current user.
     * @param \Drupal\Core\State\StateInterface $state
     *   The state service.
     * @param \Psr\Log\LoggerInterface $logger
     *   A logger instance.
     * @param \Drupal\Core\DependencyInjection\ClassResolverInterface $class_resolver
     *   The class resolver.
     * @param \Drupal\workspaces\WorkspaceAssociationInterface $workspace_association
     *   The workspace association service.
     * @param array $negotiator_ids
     *   The workspace negotiator service IDs.
     */
    public function __construct(RequestStack $request_stack, EntityTypeManagerInterface $entity_type_manager, MemoryCacheInterface $entity_memory_cache, AccountProxyInterface $current_user, StateInterface $state, LoggerInterface $logger, ClassResolverInterface $class_resolver, WorkspaceAssociationInterface $workspace_association, array $negotiator_ids) {
        $this->requestStack = $request_stack;
        $this->entityTypeManager = $entity_type_manager;
        $this->entityMemoryCache = $entity_memory_cache;
        $this->currentUser = $current_user;
        $this->state = $state;
        $this->logger = $logger;
        $this->classResolver = $class_resolver;
        $this->workspaceAssociation = $workspace_association;
        $this->negotiatorIds = $negotiator_ids;
    }
    
    /**
     * {@inheritdoc}
     */
    public function isEntityTypeSupported(EntityTypeInterface $entity_type) {
        // First, check if we already determined whether this entity type is
        // supported or not.
        if (isset($this->blacklist[$entity_type->id()])) {
            return FALSE;
        }
        if ($entity_type->entityClassImplements(EntityPublishedInterface::class) && $entity_type->isRevisionable()) {
            return TRUE;
        }
        // This entity type can not belong to a workspace, add it to the blacklist.
        $this->blacklist[$entity_type->id()] = $entity_type->id();
        return FALSE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getSupportedEntityTypes() {
        $entity_types = [];
        foreach ($this->entityTypeManager
            ->getDefinitions() as $entity_type_id => $entity_type) {
            if ($this->isEntityTypeSupported($entity_type)) {
                $entity_types[$entity_type_id] = $entity_type;
            }
        }
        return $entity_types;
    }
    
    /**
     * {@inheritdoc}
     */
    public function hasActiveWorkspace() {
        return $this->getActiveWorkspace() !== FALSE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getActiveWorkspace() {
        if (!isset($this->activeWorkspace)) {
            $request = $this->requestStack
                ->getCurrentRequest();
            foreach ($this->negotiatorIds as $negotiator_id) {
                $negotiator = $this->classResolver
                    ->getInstanceFromDefinition($negotiator_id);
                if ($negotiator->applies($request)) {
                    // By default, 'view' access is checked when a workspace is activated,
                    // but it should also be checked when retrieving the currently active
                    // workspace.
                    if (($negotiated_workspace = $negotiator->getActiveWorkspace($request)) && $negotiated_workspace->access('view')) {
                        $active_workspace = $negotiated_workspace;
                        break;
                    }
                }
            }
            // If no negotiator was able to determine the active workspace, default to
            // the live version of the site.
            $this->activeWorkspace = $active_workspace ?? FALSE;
        }
        return $this->activeWorkspace;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setActiveWorkspace(WorkspaceInterface $workspace) {
        $this->doSwitchWorkspace($workspace);
        // Set the workspace on the proper negotiator.
        $request = $this->requestStack
            ->getCurrentRequest();
        foreach ($this->negotiatorIds as $negotiator_id) {
            $negotiator = $this->classResolver
                ->getInstanceFromDefinition($negotiator_id);
            if ($negotiator->applies($request)) {
                $negotiator->setActiveWorkspace($workspace);
                break;
            }
        }
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function switchToLive() {
        $this->doSwitchWorkspace(NULL);
        // Unset the active workspace on all negotiators.
        foreach ($this->negotiatorIds as $negotiator_id) {
            $negotiator = $this->classResolver
                ->getInstanceFromDefinition($negotiator_id);
            $negotiator->unsetActiveWorkspace();
        }
        return $this;
    }
    
    /**
     * Switches the current workspace.
     *
     * @param \Drupal\workspaces\WorkspaceInterface|null $workspace
     *   The workspace to set as active or NULL to switch out of the currently
     *   active workspace.
     *
     * @throws \Drupal\workspaces\WorkspaceAccessException
     *   Thrown when the current user doesn't have access to view the workspace.
     */
    protected function doSwitchWorkspace($workspace) {
        // If the current user doesn't have access to view the workspace, they
        // shouldn't be allowed to switch to it.
        if ($workspace && !$workspace->access('view')) {
            $this->logger
                ->error('Denied access to view workspace %workspace_label for user %uid', [
                '%workspace_label' => $workspace->label(),
                '%uid' => $this->currentUser
                    ->id(),
            ]);
            throw new WorkspaceAccessException('The user does not have permission to view that workspace.');
        }
        $this->activeWorkspace = $workspace ?: FALSE;
        // Clear the static entity cache for the supported entity types.
        $cache_tags_to_invalidate = array_map(function ($entity_type_id) {
            return 'entity.memory_cache:' . $entity_type_id;
        }, array_keys($this->getSupportedEntityTypes()));
        $this->entityMemoryCache
            ->invalidateTags($cache_tags_to_invalidate);
        // Clear the static cache for path aliases. We can't inject the path alias
        // manager service because it would create a circular dependency.
        \Drupal::service('path_alias.manager')->cacheClear();
    }
    
    /**
     * {@inheritdoc}
     */
    public function executeInWorkspace($workspace_id, callable $function) {
        
        /** @var \Drupal\workspaces\WorkspaceInterface $workspace */
        $workspace = $this->entityTypeManager
            ->getStorage('workspace')
            ->load($workspace_id);
        if (!$workspace) {
            throw new \InvalidArgumentException('The ' . $workspace_id . ' workspace does not exist.');
        }
        $previous_active_workspace = $this->getActiveWorkspace();
        $this->doSwitchWorkspace($workspace);
        $result = $function();
        $this->doSwitchWorkspace($previous_active_workspace);
        return $result;
    }
    
    /**
     * {@inheritdoc}
     */
    public function executeOutsideWorkspace(callable $function) {
        $previous_active_workspace = $this->getActiveWorkspace();
        $this->doSwitchWorkspace(NULL);
        $result = $function();
        $this->doSwitchWorkspace($previous_active_workspace);
        return $result;
    }
    
    /**
     * {@inheritdoc}
     */
    public function shouldAlterOperations(EntityTypeInterface $entity_type) {
        return $this->isEntityTypeSupported($entity_type) && $this->hasActiveWorkspace();
    }
    
    /**
     * {@inheritdoc}
     */
    public function purgeDeletedWorkspacesBatch() {
        $deleted_workspace_ids = $this->state
            ->get('workspace.deleted', []);
        // Bail out early if there are no workspaces to purge.
        if (empty($deleted_workspace_ids)) {
            return;
        }
        $batch_size = Settings::get('entity_update_batch_size', 50);
        // Get the first deleted workspace from the list and delete the revisions
        // associated with it, along with the workspace association records.
        $workspace_id = reset($deleted_workspace_ids);
        $tracked_entities = $this->workspaceAssociation
            ->getTrackedEntities($workspace_id);
        $count = 1;
        foreach ($tracked_entities as $entity_type_id => $entities) {
            $associated_entity_storage = $this->entityTypeManager
                ->getStorage($entity_type_id);
            $associated_revisions = $this->workspaceAssociation
                ->getAssociatedRevisions($workspace_id, $entity_type_id);
            foreach (array_keys($associated_revisions) as $revision_id) {
                if ($count > $batch_size) {
                    continue 2;
                }
                // Delete the associated entity revision.
                $associated_entity_storage->deleteRevision($revision_id);
                $count++;
            }
            // Delete the workspace association entries.
            $this->workspaceAssociation
                ->deleteAssociations($workspace_id, $entity_type_id, $entities);
        }
        // The purging operation above might have taken a long time, so we need to
        // request a fresh list of tracked entities. If it is empty, we can go ahead
        // and remove the deleted workspace ID entry from state.
        if (!$this->workspaceAssociation
            ->getTrackedEntities($workspace_id)) {
            unset($deleted_workspace_ids[$workspace_id]);
            $this->state
                ->set('workspace.deleted', $deleted_workspace_ids);
        }
    }

}