--- /dev/null
+<?php
+
+namespace Drupal\settings_tray\Block;
+
+use Drupal\block\BlockForm;
+use Drupal\block\BlockInterface;
+use Drupal\Component\Utility\Html;
+use Drupal\Core\Ajax\AjaxResponse;
+use Drupal\Core\Ajax\RedirectCommand;
+use Drupal\Core\Ajax\ReplaceCommand;
+use Drupal\Core\Block\BlockPluginInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Plugin\PluginWithFormsInterface;
+use Drupal\Core\Url;
+
+/**
+ * Provides form for block instance forms when used in the off-canvas dialog.
+ *
+ * This form removes advanced sections of regular block form such as the
+ * visibility settings, machine ID and region.
+ *
+ * @internal
+ */
+class BlockEntitySettingTrayForm extends BlockForm {
+
+ /**
+ * Provides a title callback to get the block's admin label.
+ *
+ * @param \Drupal\block\BlockInterface $block
+ * The block entity.
+ *
+ * @return \Drupal\Core\StringTranslation\TranslatableMarkup
+ * The title.
+ */
+ public function title(BlockInterface $block) {
+ // @todo Wrap "Configure " in <span class="visually-hidden"></span> once
+ // https://www.drupal.org/node/2359901 is fixed.
+ return $this->t('Configure @block', ['@block' => $block->getPlugin()->getPluginDefinition()['admin_label']]);
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function form(array $form, FormStateInterface $form_state) {
+ $form = parent::form($form, $form_state);
+
+ // Create link to full block form.
+ $query = [];
+ if ($destination = $this->getRequest()->query->get('destination')) {
+ $query['destination'] = $destination;
+ }
+ $form['advanced_link'] = [
+ '#type' => 'link',
+ '#title' => $this->t('Advanced block options'),
+ '#url' => $this->entity->toUrl('edit-form', ['query' => $query]),
+ '#weight' => 1000,
+ ];
+
+ // Remove the ID and region elements.
+ unset($form['id'], $form['region'], $form['settings']['admin_label']);
+
+ if (isset($form['settings']['label_display']) && isset($form['settings']['label'])) {
+ // Only show the label input if the label will be shown on the page.
+ $form['settings']['label_display']['#weight'] = -100;
+ $form['settings']['label']['#states']['visible'] = [
+ ':input[name="settings[label_display]"]' => ['checked' => TRUE],
+ ];
+
+ // Relabel to "Block title" because on the front-end this may be confused
+ // with page title.
+ $form['settings']['label']['#title'] = $this->t("Block title");
+ $form['settings']['label_display']['#title'] = $this->t("Display block title");
+ }
+ return $form;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function actions(array $form, FormStateInterface $form_state) {
+ $actions = parent::actions($form, $form_state);
+ $actions['submit']['#value'] = $this->t('Save @block', ['@block' => $this->entity->getPlugin()->getPluginDefinition()['admin_label']]);
+ $actions['delete']['#access'] = FALSE;
+ return $actions;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function buildVisibilityInterface(array $form, FormStateInterface $form_state) {
+ // Do not display the visibility.
+ return [];
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function validateVisibility(array $form, FormStateInterface $form_state) {
+ // Intentionally empty.
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function submitVisibility(array $form, FormStateInterface $form_state) {
+ // Intentionally empty.
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function getPluginForm(BlockPluginInterface $block) {
+ if ($block instanceof PluginWithFormsInterface) {
+ return $this->pluginFormFactory->createInstance($block, 'settings_tray', 'configure');
+ }
+ return $block;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function buildForm(array $form, FormStateInterface $form_state) {
+ $form = parent::buildForm($form, $form_state);
+ $form['actions']['submit']['#ajax'] = [
+ 'callback' => '::submitFormDialog',
+ ];
+ $form['#attached']['library'][] = 'core/drupal.dialog.ajax';
+
+ // static::submitFormDialog() requires data-drupal-selector to be the same
+ // between the various Ajax requests. A bug in
+ // \Drupal\Core\Form\FormBuilder prevents that from happening unless
+ // $form['#id'] is also the same. Normally, #id is set to a unique HTML ID
+ // via Html::getUniqueId(), but here we bypass that in order to work around
+ // the data-drupal-selector bug. This is okay so long as we assume that this
+ // form only ever occurs once on a page.
+ // @todo Remove this workaround once https://www.drupal.org/node/2897377 is
+ // fixed.
+ $form['#id'] = Html::getId($form_state->getBuildInfo()['form_id']);
+
+ return $form;
+ }
+
+ /**
+ * Submit form dialog #ajax callback.
+ *
+ * @param array $form
+ * An associative array containing the structure of the form.
+ * @param \Drupal\Core\Form\FormStateInterface $form_state
+ * The current state of the form.
+ *
+ * @return \Drupal\Core\Ajax\AjaxResponse
+ * An AJAX response that display validation error messages or redirects
+ * to a URL
+ *
+ * @todo Repalce this callback with generic trait in
+ * https://www.drupal.org/node/2896535.
+ */
+ public function submitFormDialog(array &$form, FormStateInterface $form_state) {
+ $response = new AjaxResponse();
+ if ($form_state->hasAnyErrors()) {
+ $form['status_messages'] = [
+ '#type' => 'status_messages',
+ '#weight' => -1000,
+ ];
+ $command = new ReplaceCommand('[data-drupal-selector="' . $form['#attributes']['data-drupal-selector'] . '"]', $form);
+ }
+ else {
+ if ($redirect_url = $this->getRedirectUrl()) {
+ $command = new RedirectCommand($redirect_url->setAbsolute()->toString());
+ }
+ else {
+ // Settings Tray always provides a destination.
+ throw new \Exception("No destination provided by Settings Tray form");
+ }
+ }
+ return $response->addCommand($command);
+ }
+
+ /**
+ * Gets the form's redirect URL from 'destination' provide in the request.
+ *
+ * @return \Drupal\Core\Url|null
+ * The redirect URL or NULL if dialog should just be closed.
+ */
+ protected function getRedirectUrl() {
+ // \Drupal\Core\Routing\RedirectDestination::get() cannot be used directly
+ // because it will use <current> if 'destination' is not in the query
+ // string.
+ if ($this->getRequest()->query->has('destination') && $destination = $this->getRedirectDestination()->get()) {
+ return Url::fromUserInput('/' . $destination);
+ }
+ }
+
+}