class TermName

class TermName extends Entity {
  
  /**
   * The taxonomy term storage.
   *
   * @var \Drupal\taxonomy\TermStorageInterface
   */
  protected $termStorage;
  
  /**
   * {@inheritdoc}
   */
  public function __construct(array $configuration, $plugin_id, $plugin_definition, EntityTypeManagerInterface $entity_type_manager, EntityTypeBundleInfoInterface $entity_type_bundle_info = NULL) {
    parent::__construct($configuration, $plugin_id, $plugin_definition, $entity_type_manager, $entity_type_bundle_info);
    // Not handling exploding term names.
    $this->multipleCapable = FALSE;
    $this->termStorage = $entity_type_manager->getStorage('taxonomy_term');
  }
  
  /**
   * {@inheritdoc}
   */
  protected function defineOptions() {
    $options = parent::defineOptions();
    $options['transform'] = [
      'default' => FALSE,
    ];
    return $options;
  }
  
  /**
   * {@inheritdoc}
   */
  public function buildOptionsForm(&$form, FormStateInterface $form_state) {
    parent::buildOptionsForm($form, $form_state);
    $form['transform'] = [
      '#type' => 'checkbox',
      '#title' => $this->t('Transform dashes in URL to spaces in term name filter values'),
      '#default_value' => $this->options['transform'],
    ];
  }
  
  /**
   * {@inheritdoc}
   */
  public function validateArgument($argument) {
    if ($this->options['transform']) {
      $argument = str_replace('-', ' ', $argument);
      $this->argument->argument = $argument;
    }
    // If bundles is set then restrict the loaded terms to the given bundles.
    if (!empty($this->options['bundles'])) {
      $terms = $this->termStorage
        ->loadByProperties([
        'name' => $argument,
        'vid' => $this->options['bundles'],
      ]);
    }
    else {
      $terms = $this->termStorage
        ->loadByProperties([
        'name' => $argument,
      ]);
    }
    // $terms are already bundle tested but we need to test access control.
    foreach ($terms as $term) {
      if ($this->validateEntity($term)) {
        return TRUE;
      }
    }
    return FALSE;
  }

}