class CommentItem

class CommentItem extends FieldItemBase implements CommentItemInterface {
    
    /**
     * {@inheritdoc}
     */
    public static function defaultStorageSettings() {
        return [
            'comment_type' => '',
        ] + parent::defaultStorageSettings();
    }
    
    /**
     * {@inheritdoc}
     */
    public static function defaultFieldSettings() {
        return [
            'default_mode' => CommentManagerInterface::COMMENT_MODE_THREADED,
            'per_page' => 50,
            'form_location' => CommentItemInterface::FORM_BELOW,
            'anonymous' => CommentInterface::ANONYMOUS_MAYNOT_CONTACT,
            'preview' => DRUPAL_OPTIONAL,
        ] + parent::defaultFieldSettings();
    }
    
    /**
     * {@inheritdoc}
     */
    public static function propertyDefinitions(FieldStorageDefinitionInterface $field_definition) {
        $properties['status'] = DataDefinition::create('integer')->setLabel(t('Comment status'))
            ->setRequired(TRUE);
        $properties['cid'] = DataDefinition::create('integer')->setLabel(t('Last comment ID'));
        $properties['last_comment_timestamp'] = DataDefinition::create('integer')->setLabel(t('Last comment timestamp'))
            ->setDescription(t('The time that the last comment was created.'));
        $properties['last_comment_name'] = DataDefinition::create('string')->setLabel(t('Last comment name'))
            ->setDescription(t('The name of the user posting the last comment.'));
        $properties['last_comment_uid'] = DataDefinition::create('integer')->setLabel(t('Last comment user ID'));
        $properties['comment_count'] = DataDefinition::create('integer')->setLabel(t('Number of comments'))
            ->setDescription(t('The number of comments.'));
        return $properties;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function schema(FieldStorageDefinitionInterface $field_definition) {
        return [
            'columns' => [
                'status' => [
                    'description' => 'Whether comments are allowed on this entity: 0 = no, 1 = closed (read only), 2 = open (read/write).',
                    'type' => 'int',
                    'default' => 0,
                ],
            ],
            'indexes' => [],
            'foreign keys' => [],
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function fieldSettingsForm(array $form, FormStateInterface $form_state) {
        $element = [];
        $settings = $this->getSettings();
        $anonymous_user = new AnonymousUserSession();
        $element['default_mode'] = [
            '#type' => 'checkbox',
            '#title' => t('Threading'),
            '#default_value' => $settings['default_mode'],
            '#description' => t('Show comment replies in a threaded list.'),
        ];
        $element['per_page'] = [
            '#type' => 'number',
            '#title' => t('Comments per page'),
            '#default_value' => $settings['per_page'],
            '#required' => TRUE,
            '#min' => 1,
            '#max' => 1000,
        ];
        $element['anonymous'] = [
            '#type' => 'select',
            '#title' => t('Anonymous commenting'),
            '#default_value' => $settings['anonymous'],
            '#options' => [
                CommentInterface::ANONYMOUS_MAYNOT_CONTACT => t('Anonymous posters may not enter their contact information'),
                CommentInterface::ANONYMOUS_MAY_CONTACT => t('Anonymous posters may leave their contact information'),
                CommentInterface::ANONYMOUS_MUST_CONTACT => t('Anonymous posters must leave their contact information'),
            ],
            '#access' => $anonymous_user->hasPermission('post comments'),
        ];
        $element['form_location'] = [
            '#type' => 'checkbox',
            '#title' => t('Show reply form on the same page as comments'),
            '#default_value' => $settings['form_location'],
        ];
        $element['preview'] = [
            '#type' => 'radios',
            '#title' => t('Preview comment'),
            '#default_value' => $settings['preview'],
            '#options' => [
                DRUPAL_DISABLED => t('Disabled'),
                DRUPAL_OPTIONAL => t('Optional'),
                DRUPAL_REQUIRED => t('Required'),
            ],
        ];
        return $element;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function mainPropertyName() {
        return 'status';
    }
    
    /**
     * {@inheritdoc}
     */
    public function isEmpty() {
        // There is always a value for this field, it is one of
        // CommentItemInterface::OPEN, CommentItemInterface::CLOSED or
        // CommentItemInterface::HIDDEN.
        return FALSE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function storageSettingsForm(array &$form, FormStateInterface $form_state, $has_data) {
        $element = [];
        // @todo Inject entity storage once typed-data supports container injection.
        //   See https://www.drupal.org/node/2053415 for more details.
        $comment_types = CommentType::loadMultiple();
        $options = [];
        $entity_type = $this->getEntity()
            ->getEntityTypeId();
        foreach ($comment_types as $comment_type) {
            if ($comment_type->getTargetEntityTypeId() == $entity_type) {
                $options[$comment_type->id()] = $comment_type->label();
            }
        }
        $element['comment_type'] = [
            '#type' => 'select',
            '#title' => t('Comment type'),
            '#options' => $options,
            '#required' => TRUE,
            '#description' => $this->t('Select the Comment type to use for this comment field. Manage the comment types from the <a href=":url">administration overview page</a>.', [
                ':url' => Url::fromRoute('entity.comment_type.collection')->toString(),
            ]),
            '#default_value' => $this->getSetting('comment_type'),
            '#disabled' => $has_data,
        ];
        return $element;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function generateSampleValue(FieldDefinitionInterface $field_definition) {
        $statuses = [
            CommentItemInterface::HIDDEN,
            CommentItemInterface::CLOSED,
            CommentItemInterface::OPEN,
        ];
        return [
            'status' => $statuses[mt_rand(0, count($statuses) - 1)],
        ];
    }

}