+<?php
+
+namespace Drupal\ctools\Form;
+
+use Drupal\Core\Form\ConfirmFormBase;
+use Drupal\Core\Form\ConfirmFormHelper;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Url;
+use Drupal\user\SharedTempStoreFactory;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Base class for adding a required contexts step to your wizard.
+ */
+abstract class RequiredContextDelete extends ConfirmFormBase {
+
+ /**
+ * @var \Drupal\user\SharedTempStoreFactory
+ */
+ protected $tempstore;
+
+ /**
+ * @var string
+ */
+ protected $tempstore_id;
+
+ /**
+ * @var string;
+ */
+ protected $machine_name;
+
+ /**
+ * @var int;
+ */
+ protected $id;
+
+ /**
+ * {@inheritdoc}
+ */
+ public static function create(ContainerInterface $container) {
+ return new static($container->get('user.shared_tempstore'));
+ }
+
+ /**
+ * @param \Drupal\user\SharedTempStoreFactory $tempstore
+ */
+ function __construct(SharedTempStoreFactory $tempstore) {
+ $this->tempstore = $tempstore;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getFormId() {
+ return 'ctools_required_context_delete';
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function buildForm(array $form, FormStateInterface $form_state, $id = NULL, $tempstore_id = NULL, $machine_name = NULL) {
+ $this->tempstore_id = $tempstore_id;
+ $this->machine_name = $machine_name;
+ $this->id = $id;
+
+ $cached_values = $this->tempstore->get($this->tempstore_id)->get($this->machine_name);
+ $form ['#title'] = $this->getQuestion($id, $cached_values);
+
+ $form ['#attributes']['class'][] = 'confirmation';
+ $form ['description'] = array('#markup' => $this->getDescription());
+ $form [$this->getFormName()] = array('#type' => 'hidden', '#value' => 1);
+
+ // By default, render the form using theme_confirm_form().
+ if (!isset($form ['#theme'])) {
+ $form ['#theme'] = 'confirm_form';
+ }
+ $form['actions'] = array('#type' => 'actions');
+ $form['actions'] += $this->actions($form, $form_state);
+ return $form;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function submitForm(array &$form, FormStateInterface $form_state) {
+ $cached_values = $this->tempstore->get($this->tempstore_id)->get($this->machine_name);
+ $contexts = $this->getContexts($cached_values);
+ unset($contexts[$this->id]);
+ $cached_values = $this->setContexts($cached_values, $contexts);
+ $this->tempstore->get($this->tempstore_id)->set($this->machine_name, $cached_values);
+ list($route_name, $route_parameters) = $this->getParentRouteInfo($cached_values);
+ $form_state->setRedirect($route_name, $route_parameters);
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getQuestion($id = NULL, $cached_values = NULL) {
+ $context = $this->getContexts($cached_values)[$id];
+ return $this->t('Are you sure you want to delete the @label context?', array(
+ '@label' => $context['label'],
+ ));
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getDescription() {
+ return $this->t('This action cannot be undone.');
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getFormName() {
+ return 'confirm';
+ }
+
+ /**
+ * Provides the action buttons for submitting this form.
+ */
+ protected function actions(array $form, FormStateInterface $form_state) {
+ return array(
+ 'submit' => array(
+ '#type' => 'submit',
+ '#value' => $this->getConfirmText(),
+ '#validate' => array(
+ array($this, 'validate'),
+ ),
+ '#submit' => array(
+ array($this, 'submitForm'),
+ ),
+ ),
+ 'cancel' => ConfirmFormHelper::buildCancelLink($this, $this->getRequest()),
+ );
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getCancelUrl() {
+ $cached_values = $this->tempstore->get($this->tempstore_id)->get($this->machine_name);
+ list($route_name, $route_parameters) = $this->getParentRouteInfo($cached_values);
+ return new Url($route_name, $route_parameters);
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getConfirmText() {
+ return $this->t('Delete');
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getCancelText() {
+ return $this->t('Cancel');
+ }
+
+ /**
+ * Document the route name and parameters for redirect after submission.
+ *
+ * @param $cached_values
+ *
+ * @return array
+ * In the format of
+ * return ['route.name', ['machine_name' => $this->machine_name, 'step' => 'step_name]];
+ */
+ abstract protected function getParentRouteInfo($cached_values);
+
+ /**
+ * Custom logic for retrieving the contexts array from cached_values.
+ *
+ * @param $cached_values
+ *
+ * @return array
+ */
+ abstract protected function getContexts($cached_values);
+
+ /**
+ * Custom logic for setting the contexts array in cached_values.
+ *
+ * @param $cached_values
+ *
+ * @param $contexts
+ * The contexts to set within the cached values.
+ *
+ * @return mixed
+ * Return the $cached_values
+ */
+ abstract protected function setContexts($cached_values, $contexts);
+
+}