class MenuLinkContent

class MenuLinkContent extends EditorialContentEntityBase implements MenuLinkContentInterface {
    
    /**
     * A flag for whether this entity is wrapped in a plugin instance.
     *
     * @var bool
     */
    protected $insidePlugin = FALSE;
    
    /**
     * {@inheritdoc}
     */
    public function setInsidePlugin() {
        $this->insidePlugin = TRUE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getTitle() {
        return $this->get('title')->value;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getUrlObject() {
        return $this->link
            ->first()
            ->getUrl();
    }
    
    /**
     * {@inheritdoc}
     */
    public function getMenuName() {
        return $this->get('menu_name')->value;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getDescription() {
        return $this->get('description')->value;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getPluginId() {
        return 'menu_link_content:' . $this->uuid();
    }
    
    /**
     * {@inheritdoc}
     */
    public function isEnabled() {
        return (bool) $this->get('enabled')->value;
    }
    
    /**
     * {@inheritdoc}
     */
    public function isExpanded() {
        return (bool) $this->get('expanded')->value;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getParentId() {
        // Cast the parent ID to a string, only an empty string means no parent,
        // NULL keeps the existing parent.
        return (string) $this->get('parent')->value;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getWeight() {
        return (int) $this->get('weight')->value;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getPluginDefinition() {
        $definition = [];
        $definition['class'] = 'Drupal\\menu_link_content\\Plugin\\Menu\\MenuLinkContent';
        $definition['menu_name'] = $this->getMenuName();
        if ($url_object = $this->getUrlObject()) {
            $definition['url'] = NULL;
            $definition['route_name'] = NULL;
            $definition['route_parameters'] = [];
            if (!$url_object->isRouted()) {
                $definition['url'] = $url_object->getUri();
            }
            else {
                $definition['route_name'] = $url_object->getRouteName();
                $definition['route_parameters'] = $url_object->getRouteParameters();
            }
            $definition['options'] = $url_object->getOptions();
        }
        $definition['title'] = $this->getTitle();
        $definition['description'] = $this->getDescription();
        $definition['weight'] = $this->getWeight();
        $definition['id'] = $this->getPluginId();
        $definition['metadata'] = [
            'entity_id' => $this->id(),
        ];
        $definition['form_class'] = '\\Drupal\\menu_link_content\\Form\\MenuLinkContentForm';
        $definition['enabled'] = $this->isEnabled() ? 1 : 0;
        $definition['expanded'] = $this->isExpanded() ? 1 : 0;
        $definition['provider'] = 'menu_link_content';
        $definition['discovered'] = 0;
        $definition['parent'] = $this->getParentId();
        return $definition;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function preCreate(EntityStorageInterface $storage, array &$values) {
        $values += [
            'bundle' => 'menu_link_content',
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function preSave(EntityStorageInterface $storage) {
        parent::preSave($storage);
        if (parse_url($this->link->uri, PHP_URL_SCHEME) === 'internal') {
            $this->setRequiresRediscovery(TRUE);
        }
        else {
            $this->setRequiresRediscovery(FALSE);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function postSave(EntityStorageInterface $storage, $update = TRUE) {
        parent::postSave($storage, $update);
        // Don't update the menu tree if a pending revision was saved.
        if (!$this->isDefaultRevision()) {
            return;
        }
        
        /** @var \Drupal\Core\Menu\MenuLinkManagerInterface $menu_link_manager */
        $menu_link_manager = \Drupal::service('plugin.manager.menu.link');
        // The menu link can just be updated if there is already a menu link entry
        // on both entity and menu link plugin level.
        $definition = $this->getPluginDefinition();
        // Even when $update is FALSE, for top level links it is possible the link
        // already is in the storage because of the getPluginDefinition() call
        // above, see https://www.drupal.org/node/2605684#comment-10515450 for the
        // call chain. Because of this the $update flag is ignored and only the
        // existence of the definition (equals to being in the tree storage) is
        // checked.
        if ($menu_link_manager->getDefinition($this->getPluginId(), FALSE)) {
            // When the entity is saved via a plugin instance, we should not call
            // the menu tree manager to update the definition a second time.
            if (!$this->insidePlugin) {
                $menu_link_manager->updateDefinition($this->getPluginId(), $definition, FALSE);
            }
        }
        else {
            $menu_link_manager->addDefinition($this->getPluginId(), $definition);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public static function preDelete(EntityStorageInterface $storage, array $entities) {
        parent::preDelete($storage, $entities);
        
        /** @var \Drupal\Core\Menu\MenuLinkManagerInterface $menu_link_manager */
        $menu_link_manager = \Drupal::service('plugin.manager.menu.link');
        foreach ($entities as $menu_link) {
            
            /** @var \Drupal\menu_link_content\Entity\MenuLinkContent $menu_link */
            $menu_link_manager->removeDefinition($menu_link->getPluginId(), FALSE);
            // Children get re-attached to the menu link's parent.
            $parent_plugin_id = $menu_link->getParentId();
            $children = $storage->loadByProperties([
                'parent' => $menu_link->getPluginId(),
            ]);
            foreach ($children as $child) {
                
                /** @var \Drupal\menu_link_content\Entity\MenuLinkContent $child */
                $child->set('parent', $parent_plugin_id)
                    ->save();
            }
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
        
        /** @var \Drupal\Core\Field\BaseFieldDefinition[] $fields */
        $fields = parent::baseFieldDefinitions($entity_type);
        // Add the publishing status field.
        $fields += static::publishedBaseFieldDefinitions($entity_type);
        $fields['id']->setLabel(t('Entity ID'))
            ->setDescription(t('The entity ID for this menu link content entity.'));
        $fields['uuid']->setDescription(t('The content menu link UUID.'));
        $fields['langcode']->setDescription(t('The menu link language code.'));
        $fields['bundle']->setDescription(t('The content menu link bundle.'))
            ->setSetting('max_length', EntityTypeInterface::BUNDLE_MAX_LENGTH)
            ->setSetting('is_ascii', TRUE);
        $fields['title'] = BaseFieldDefinition::create('string')->setLabel(t('Menu link title'))
            ->setDescription(t('The text to be used for this link in the menu.'))
            ->setRequired(TRUE)
            ->setTranslatable(TRUE)
            ->setRevisionable(TRUE)
            ->setSetting('max_length', 255)
            ->setDisplayOptions('view', [
            'label' => 'hidden',
            'type' => 'string',
            'weight' => -5,
        ])
            ->setDisplayOptions('form', [
            'type' => 'string_textfield',
            'weight' => -5,
        ])
            ->setDisplayConfigurable('form', TRUE);
        $fields['description'] = BaseFieldDefinition::create('string')->setLabel(t('Description'))
            ->setDescription(t('Shown when hovering over the menu link.'))
            ->setTranslatable(TRUE)
            ->setRevisionable(TRUE)
            ->setSetting('max_length', 255)
            ->setDisplayOptions('view', [
            'label' => 'hidden',
            'type' => 'string',
            'weight' => 0,
        ])
            ->setDisplayOptions('form', [
            'type' => 'string_textfield',
            'weight' => 0,
        ]);
        $fields['menu_name'] = BaseFieldDefinition::create('string')->setLabel(t('Menu name'))
            ->setDescription(t('The menu name. All links with the same menu name (such as "tools") are part of the same menu.'))
            ->setDefaultValue('tools')
            ->setSetting('is_ascii', TRUE);
        $fields['link'] = BaseFieldDefinition::create('link')->setLabel(t('Link'))
            ->setDescription(t('The location this menu link points to.'))
            ->setRevisionable(TRUE)
            ->setRequired(TRUE)
            ->setSettings([
            'link_type' => LinkItemInterface::LINK_GENERIC,
            'title' => DRUPAL_DISABLED,
        ])
            ->setDisplayOptions('form', [
            'type' => 'link_default',
            'weight' => -2,
        ]);
        $fields['external'] = BaseFieldDefinition::create('boolean')->setLabel(t('External'))
            ->setDescription(t('A flag to indicate if the link points to a full URL starting with a protocol, like http:// (1 = external, 0 = internal).'))
            ->setDefaultValue(FALSE)
            ->setRevisionable(TRUE);
        $fields['rediscover'] = BaseFieldDefinition::create('boolean')->setLabel(t('Indicates whether the menu link should be rediscovered'))
            ->setDefaultValue(FALSE);
        $fields['weight'] = BaseFieldDefinition::create('integer')->setLabel(t('Weight'))
            ->setDescription(t('Link weight among links in the same menu at the same depth. In the menu, the links with high weight will sink and links with a low weight will be positioned nearer the top.'))
            ->setDefaultValue(0)
            ->setDisplayOptions('view', [
            'label' => 'hidden',
            'type' => 'number_integer',
            'weight' => 0,
        ])
            ->setDisplayOptions('form', [
            'type' => 'number',
            'weight' => 20,
        ]);
        $fields['expanded'] = BaseFieldDefinition::create('boolean')->setLabel(t('Show as expanded'))
            ->setDescription(t('If selected and this menu link has children, the menu will always appear expanded. This option may be overridden for the entire menu tree when placing a menu block.'))
            ->setDefaultValue(FALSE)
            ->setDisplayOptions('view', [
            'label' => 'hidden',
            'type' => 'boolean',
            'weight' => 0,
        ])
            ->setDisplayOptions('form', [
            'settings' => [
                'display_label' => TRUE,
            ],
            'weight' => 0,
        ]);
        // Override some properties of the published field added by
        // \Drupal\Core\Entity\EntityPublishedTrait::publishedBaseFieldDefinitions().
        $fields['enabled']->setLabel(t('Enabled'));
        $fields['enabled']->setDescription(t('A flag for whether the link should be enabled in menus or hidden.'));
        $fields['enabled']->setTranslatable(FALSE);
        $fields['enabled']->setDisplayOptions('view', [
            'label' => 'hidden',
            'type' => 'boolean',
            'weight' => 0,
        ]);
        $fields['enabled']->setDisplayOptions('form', [
            'settings' => [
                'display_label' => TRUE,
            ],
            'weight' => -1,
        ]);
        $fields['parent'] = BaseFieldDefinition::create('string')->setLabel(t('Parent plugin ID'))
            ->setDescription(t('The ID of the parent menu link plugin, or empty string when at the top level of the hierarchy.'));
        $fields['changed'] = BaseFieldDefinition::create('changed')->setLabel(t('Changed'))
            ->setDescription(t('The time that the menu link was last edited.'))
            ->setTranslatable(TRUE)
            ->setRevisionable(TRUE);
        // @todo Keep this field hidden until we have a revision UI for menu links.
        //   @see https://www.drupal.org/project/drupal/issues/2350939
        $fields['revision_log_message']->setDisplayOptions('form', [
            'region' => 'hidden',
        ]);
        return $fields;
    }
    
    /**
     * {@inheritdoc}
     */
    public function requiresRediscovery() {
        return $this->get('rediscover')->value;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setRequiresRediscovery($rediscovery) {
        $this->set('rediscover', $rediscovery);
        return $this;
    }

}