--- /dev/null
+<?php
+
+namespace Drupal\workflows\Form;
+
+use Drupal\Core\Entity\EntityForm;
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Class WorkflowStateAddForm.
+ */
+class WorkflowStateAddForm extends EntityForm {
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getFormId() {
+ return 'workflow_state_add_form';
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function form(array $form, FormStateInterface $form_state) {
+ $form = parent::form($form, $form_state);
+
+ /* @var \Drupal\workflows\WorkflowInterface $workflow */
+ $workflow = $this->getEntity();
+ $form['label'] = [
+ '#type' => 'textfield',
+ '#title' => $this->t('Label'),
+ '#maxlength' => 255,
+ '#default_value' => '',
+ '#description' => $this->t('Label for the state.'),
+ '#required' => TRUE,
+ ];
+
+ $form['id'] = [
+ '#type' => 'machine_name',
+ '#machine_name' => [
+ 'exists' => [$this, 'exists'],
+ ],
+ ];
+
+ // Add additional form fields from the workflow type plugin.
+ $form['type_settings'] = [
+ $workflow->get('type') => $workflow->getTypePlugin()->buildStateConfigurationForm($form_state, $workflow),
+ '#tree' => TRUE,
+ ];
+
+ return $form;
+ }
+
+ /**
+ * Determines if the workflow state already exists.
+ *
+ * @param string $state_id
+ * The workflow state ID.
+ *
+ * @return bool
+ * TRUE if the workflow state exists, FALSE otherwise.
+ */
+ public function exists($state_id) {
+ /** @var \Drupal\workflows\WorkflowInterface $original_workflow */
+ $original_workflow = \Drupal::entityTypeManager()->getStorage('workflow')->loadUnchanged($this->getEntity()->id());
+ return $original_workflow->hasState($state_id);
+ }
+
+ /**
+ * Copies top-level form values to entity properties
+ *
+ * This form can only change values for a state, which is part of workflow.
+ *
+ * @param \Drupal\Core\Entity\EntityInterface $entity
+ * The entity the current form should operate upon.
+ * @param array $form
+ * A nested array of form elements comprising the form.
+ * @param \Drupal\Core\Form\FormStateInterface $form_state
+ * The current state of the form.
+ */
+ protected function copyFormValuesToEntity(EntityInterface $entity, array $form, FormStateInterface $form_state) {
+ /** @var \Drupal\workflows\WorkflowInterface $entity */
+ $values = $form_state->getValues();
+
+ // This is fired twice so we have to check that the entity does not already
+ // have the state.
+ if (!$entity->hasState($values['id'])) {
+ $entity->addState($values['id'], $values['label']);
+ if (isset($values['type_settings'])) {
+ $configuration = $entity->getTypePlugin()->getConfiguration();
+ $configuration['states'][$values['id']] = $values['type_settings'][$entity->getTypePlugin()->getPluginId()];
+ $entity->set('type_settings', $configuration);
+ }
+ }
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function save(array $form, FormStateInterface $form_state) {
+ /** @var \Drupal\workflows\WorkflowInterface $workflow */
+ $workflow = $this->entity;
+ $workflow->save();
+ drupal_set_message($this->t('Created %label state.', [
+ '%label' => $workflow->getState($form_state->getValue('id'))->label(),
+ ]));
+ $form_state->setRedirectUrl($workflow->toUrl('edit-form'));
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function actions(array $form, FormStateInterface $form_state) {
+ $actions['submit'] = [
+ '#type' => 'submit',
+ '#value' => $this->t('Save'),
+ '#submit' => ['::submitForm', '::save'],
+ ];
+ return $actions;
+ }
+
+}