class Workflow

class Workflow extends ConfigEntityBase implements WorkflowInterface, EntityWithPluginCollectionInterface {
  
  /**
   * The Workflow ID.
   *
   * @var string
   */
  protected $id;
  
  /**
   * The workflow label.
   *
   * @var string
   */
  protected $label;
  
  /**
   * The workflow type plugin ID.
   *
   * @var string
   *
   * @see \Drupal\workflows\WorkflowTypeManager
   */
  protected $type;
  
  /**
   * The configuration for the workflow type plugin.
   *
   * @var array
   */
  protected $type_settings = [];
  
  /**
   * The workflow type plugin collection.
   *
   * @var \Drupal\Component\Plugin\LazyPluginCollection
   */
  protected $pluginCollection;
  
  /**
   * {@inheritdoc}
   */
  public function preSave(EntityStorageInterface $storage) {
    $workflow_type = $this->getTypePlugin();
    $missing_states = array_diff($workflow_type->getRequiredStates(), array_keys($this->getTypePlugin()
      ->getStates()));
    if (!empty($missing_states)) {
      throw new RequiredStateMissingException(sprintf("Workflow type '{$workflow_type->label()}' requires states with the ID '%s' in workflow '{$this->id()}'", implode("', '", $missing_states)));
    }
    parent::preSave($storage);
  }
  
  /**
   * {@inheritdoc}
   */
  public function getTypePlugin() {
    return $this->getPluginCollection()
      ->get($this->type);
  }
  
  /**
   * {@inheritdoc}
   */
  public function getPluginCollections() {
    return [
      'type_settings' => $this->getPluginCollection(),
    ];
  }
  
  /**
   * Encapsulates the creation of the workflow's plugin collection.
   *
   * @return \Drupal\Core\Plugin\DefaultSingleLazyPluginCollection
   *   The workflow's plugin collection.
   */
  protected function getPluginCollection() {
    if (!$this->pluginCollection && $this->type) {
      $this->pluginCollection = new DefaultSingleLazyPluginCollection(\Drupal::service('plugin.manager.workflows.type'), $this->type, $this->type_settings);
    }
    return $this->pluginCollection;
  }
  
  /**
   * Loads all workflows of the provided type.
   *
   * @param string $type
   *   The workflow type to load all workflows for.
   *
   * @return static[]
   *   An array of workflow objects of the provided workflow type, indexed by
   *   their IDs.
   *
   *  @see \Drupal\workflows\Annotation\WorkflowType
   */
  public static function loadMultipleByType($type) {
    return self::loadMultiple(\Drupal::entityQuery('workflow')->condition('type', $type)
      ->execute());
  }
  
  /**
   * {@inheritdoc}
   */
  public function status() {
    // In order for a workflow to be usable it must have at least one state.
    return !empty($this->status) && !empty($this->getTypePlugin()
      ->getStates());
  }
  
  /**
   * {@inheritdoc}
   */
  public function onDependencyRemoval(array $dependencies) {
    // Give the parent method and the workflow type plugin a chance to react
    // to removed dependencies and report if either of these two made a change.
    $parent_changed_entity = parent::onDependencyRemoval($dependencies);
    $plugin_changed_entity = $this->getTypePlugin()
      ->onDependencyRemoval($dependencies);
    return $plugin_changed_entity || $parent_changed_entity;
  }

}