trait FieldLayoutEntityDisplayTrait

trait FieldLayoutEntityDisplayTrait {
    
    /**
     * Gets a layout definition.
     *
     * @param string $layout_id
     *   The layout ID.
     *
     * @return \Drupal\Core\Layout\LayoutDefinition
     *   The layout definition.
     */
    protected function getLayoutDefinition($layout_id) {
        return \Drupal::service('plugin.manager.core.layout')->getDefinition($layout_id);
    }
    
    /**
     * Implements \Drupal\field_layout\Display\EntityDisplayWithLayoutInterface::getLayoutId().
     */
    public function getLayoutId() {
        return $this->getThirdPartySetting('field_layout', 'id');
    }
    
    /**
     * Implements \Drupal\field_layout\Display\EntityDisplayWithLayoutInterface::getLayoutSettings().
     */
    public function getLayoutSettings() {
        return $this->getThirdPartySetting('field_layout', 'settings', []);
    }
    
    /**
     * Implements \Drupal\field_layout\Display\EntityDisplayWithLayoutInterface::setLayoutId().
     */
    public function setLayoutId($layout_id, array $layout_settings = []) {
        if ($this->getLayoutId() !== $layout_id) {
            // @todo Devise a mechanism for mapping old regions to new ones in
            //   https://www.drupal.org/node/2796877.
            $layout_definition = $this->getLayoutDefinition($layout_id);
            $new_region = $layout_definition->getDefaultRegion();
            $layout_regions = $layout_definition->getRegions();
            foreach ($this->getComponents() as $name => $component) {
                if (isset($component['region']) && !isset($layout_regions[$component['region']])) {
                    $component['region'] = $new_region;
                    $this->setComponent($name, $component);
                }
            }
        }
        $this->setThirdPartySetting('field_layout', 'id', $layout_id);
        // Instantiate the plugin and consult it for the updated plugin
        // configuration. Once layouts are no longer stored as third party settings,
        // this will be handled by the code in
        // \Drupal\Core\Config\Entity\ConfigEntityBase::set() that handles
        // \Drupal\Core\Entity\EntityWithPluginCollectionInterface.
        $layout_settings = $this->doGetLayout($layout_id, $layout_settings)
            ->getConfiguration();
        $this->setThirdPartySetting('field_layout', 'settings', $layout_settings);
        return $this;
    }
    
    /**
     * Implements \Drupal\field_layout\Display\EntityDisplayWithLayoutInterface::setLayout().
     */
    public function setLayout(LayoutInterface $layout) {
        $this->setLayoutId($layout->getPluginId(), $layout->getConfiguration());
        return $this;
    }
    
    /**
     * Implements \Drupal\field_layout\Display\EntityDisplayWithLayoutInterface::getLayout().
     */
    public function getLayout() {
        return $this->doGetLayout($this->getLayoutId(), $this->getLayoutSettings());
    }
    
    /**
     * Gets the layout plugin.
     *
     * @param string $layout_id
     *   A layout plugin ID.
     * @param array $layout_settings
     *   An array of settings.
     *
     * @return \Drupal\Core\Layout\LayoutInterface
     *   The layout plugin.
     */
    protected function doGetLayout($layout_id, array $layout_settings) {
        return \Drupal::service('plugin.manager.core.layout')->createInstance($layout_id, $layout_settings);
    }
    
    /**
     * Overrides \Drupal\Core\Entity\EntityDisplayBase::init().
     */
    protected function init() {
        $this->ensureLayout();
        parent::init();
    }
    
    /**
     * Overrides \Drupal\Core\Entity\EntityDisplayBase::preSave().
     */
    public function preSave(EntityStorageInterface $storage) {
        parent::preSave($storage);
        // Ensure the plugin configuration is updated. Once layouts are no longer
        // stored as third party settings, this will be handled by the code in
        // \Drupal\Core\Config\Entity\ConfigEntityBase::preSave() that handles
        // \Drupal\Core\Entity\EntityWithPluginCollectionInterface.
        if ($this->getLayoutId()) {
            $this->setLayout($this->getLayout());
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function ensureLayout($default_layout_id = 'layout_onecol') {
        if (!$this->getLayoutId()) {
            $this->setLayoutId($default_layout_id);
        }
        return $this;
    }
    
    /**
     * Overrides \Drupal\Core\Entity\EntityDisplayBase::calculateDependencies().
     *
     * Ensure the plugin dependencies are included. Once layouts are no longer
     * stored as third party settings, this will be handled by the code in
     * \Drupal\Core\Config\Entity\ConfigEntityBase::calculateDependencies() that
     * handles \Drupal\Core\Entity\EntityWithPluginCollectionInterface.
     */
    public function calculateDependencies() {
        parent::calculateDependencies();
        // This can be called during uninstallation, so check for a valid ID first.
        if ($this->getLayoutId()) {
            $this->calculatePluginDependencies($this->getLayout());
        }
        return $this;
    }
    
    /**
     * Implements \Drupal\field_layout\Display\EntityDisplayWithLayoutInterface::getDefaultRegion().
     */
    public function getDefaultRegion() {
        return $this->getLayoutDefinition($this->getLayoutId())
            ->getDefaultRegion();
    }

}