class BlockContentTypeForm

class BlockContentTypeForm extends BundleEntityFormBase {
    
    /**
     * {@inheritdoc}
     */
    public function form(array $form, FormStateInterface $form_state) {
        $form = parent::form($form, $form_state);
        
        /** @var \Drupal\block_content\BlockContentTypeInterface $block_type */
        $block_type = $this->entity;
        if ($this->operation == 'add') {
            $form['#title'] = $this->t('Add block type');
        }
        else {
            $form['#title'] = $this->t('Edit %label block type', [
                '%label' => $block_type->label(),
            ]);
        }
        $form['label'] = [
            '#type' => 'textfield',
            '#title' => $this->t('Label'),
            '#maxlength' => 255,
            '#default_value' => $block_type->label(),
            '#description' => $this->t("The human-readable name for this block type, displayed on the <em>Block types</em> page."),
            '#required' => TRUE,
        ];
        $form['id'] = [
            '#type' => 'machine_name',
            '#default_value' => $block_type->id(),
            '#machine_name' => [
                'exists' => '\\Drupal\\block_content\\Entity\\BlockContentType::load',
            ],
            '#description' => $this->t("Unique machine-readable name: lowercase letters, numbers, and underscores only."),
            '#maxlength' => EntityTypeInterface::BUNDLE_MAX_LENGTH,
        ];
        $form['description'] = [
            '#type' => 'textarea',
            '#default_value' => $block_type->getDescription(),
            '#description' => $this->t('Displays on the <em>Block types</em> page.'),
            '#title' => $this->t('Description'),
        ];
        $form['revision'] = [
            '#type' => 'checkbox',
            '#title' => $this->t('Create new revision'),
            '#default_value' => $block_type->shouldCreateNewRevision(),
            '#description' => $this->t('Create a new revision by default for this block type.'),
        ];
        if ($this->moduleHandler
            ->moduleExists('language')) {
            $form['language'] = [
                '#type' => 'details',
                '#title' => $this->t('Language settings'),
                '#group' => 'additional_settings',
            ];
            $language_configuration = ContentLanguageSettings::loadByEntityTypeBundle('block_content', $block_type->id());
            $form['language']['language_configuration'] = [
                '#type' => 'language_configuration',
                '#entity_information' => [
                    'entity_type' => 'block_content',
                    'bundle' => $block_type->id(),
                ],
                '#default_value' => $language_configuration,
            ];
            $form['#submit'][] = 'language_configuration_element_submit';
        }
        $form['actions'] = [
            '#type' => 'actions',
        ];
        $form['actions']['submit'] = [
            '#type' => 'submit',
            '#value' => $this->t('Save'),
        ];
        return $this->protectBundleIdElement($form);
    }
    
    /**
     * {@inheritdoc}
     */
    protected function copyFormValuesToEntity(EntityInterface $entity, array $form, FormStateInterface $form_state) {
        // An empty description violates config schema.
        if (trim($form_state->getValue('description', '')) === '') {
            $form_state->unsetValue('description');
        }
        parent::copyFormValuesToEntity($entity, $form, $form_state);
    }
    
    /**
     * {@inheritdoc}
     */
    public function save(array $form, FormStateInterface $form_state) {
        $block_type = $this->entity;
        $status = $block_type->save();
        $edit_link = $this->entity
            ->toLink($this->t('Edit'), 'edit-form')
            ->toString();
        $logger = $this->logger('block_content');
        if ($status == SAVED_UPDATED) {
            $this->messenger()
                ->addStatus($this->t('Block type %label has been updated.', [
                '%label' => $block_type->label(),
            ]));
            $logger->notice('Block type %label has been updated.', [
                '%label' => $block_type->label(),
                'link' => $edit_link,
            ]);
        }
        else {
            block_content_add_body_field($block_type->id());
            $this->messenger()
                ->addStatus($this->t('Block type %label has been added.', [
                '%label' => $block_type->label(),
            ]));
            $logger->notice('Block type %label has been added.', [
                '%label' => $block_type->label(),
                'link' => $edit_link,
            ]);
        }
        $form_state->setRedirectUrl($this->entity
            ->toUrl('collection'));
    }

}