--- /dev/null
+<?php
+
+namespace Drupal\layout_builder\Form;
+
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\layout_builder\SectionComponent;
+use Drupal\layout_builder\SectionStorageInterface;
+
+/**
+ * Provides a form to add a block.
+ *
+ * @internal
+ */
+class AddBlockForm extends ConfigureBlockFormBase {
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getFormId() {
+ return 'layout_builder_add_block';
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function submitLabel() {
+ return $this->t('Add Block');
+ }
+
+ /**
+ * Builds the form for the block.
+ *
+ * @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.
+ * @param \Drupal\layout_builder\SectionStorageInterface $section_storage
+ * The section storage being configured.
+ * @param int $delta
+ * The delta of the section.
+ * @param string $region
+ * The region of the block.
+ * @param string|null $plugin_id
+ * The plugin ID of the block to add.
+ *
+ * @return array
+ * The form array.
+ */
+ public function buildForm(array $form, FormStateInterface $form_state, SectionStorageInterface $section_storage = NULL, $delta = NULL, $region = NULL, $plugin_id = NULL) {
+ // Only generate a new component once per form submission.
+ if (!$component = $form_state->getTemporaryValue('layout_builder__component')) {
+ $component = new SectionComponent($this->uuidGenerator->generate(), $region, ['id' => $plugin_id]);
+ $section_storage->getSection($delta)->appendComponent($component);
+ $form_state->setTemporaryValue('layout_builder__component', $component);
+ }
+ return $this->doBuildForm($form, $form_state, $section_storage, $delta, $component);
+ }
+
+}