trait ConfigImportFormTrait in Configuration Split 2.0.x

trait ConfigImportFormTrait {
  use ConfigImporterTrait;

  /**
   * The split manager.
   *
   * @var \Drupal\config_split\ConfigSplitManager
   */
  protected $manager;

  /**
   * {@inheritdoc}
   */
  protected function buildFormWithStorageComparer(array $form, FormStateInterface $form_state, StorageComparer $storage_comparer, array $options, $validate = TRUE) {
    $form['actions'] = [
      '#type' => 'actions',
    ];
    $form['actions']['submit'] = [
      '#type' => 'submit',
      '#value' => $options['operation label'],
    ];
    if (!$storage_comparer
      ->createChangelist()
      ->hasChanges()) {
      $form['no_changes'] = [
        '#type' => 'table',
        '#header' => [
          $this
            ->t('Name'),
          $this
            ->t('Operations'),
        ],
        '#rows' => [],
        '#empty' => $this
          ->t('There are no configuration changes to make.'),
      ];
      $form['actions']['#access'] = FALSE;
      return $form;
    }
    elseif ($validate && !$storage_comparer
      ->validateSiteUuid()) {
      $this
        ->messenger()
        ->addError($this
        ->t('The staged configuration cannot be imported, because it originates from a different site than this site. You can only synchronize configuration between cloned instances of this site.'));
      $form['actions']['#access'] = FALSE;
      return $form;
    }

    // Store the comparer for use in the submit.
    $form_state
      ->set('storage_comparer', $storage_comparer);

    // Add the AJAX library to the form for dialog support.
    $form['#attached']['library'][] = 'core/drupal.dialog.ajax';
    foreach ($storage_comparer
      ->getAllCollectionNames() as $collection) {
      if ($collection != StorageInterface::DEFAULT_COLLECTION) {
        $form[$collection]['collection_heading'] = [
          '#type' => 'html_tag',
          '#tag' => 'h2',
          '#value' => $this
            ->t('@collection configuration collection', [
            '@collection' => $collection,
          ]),
        ];
      }
      foreach ($storage_comparer
        ->getChangelist(NULL, $collection) as $config_change_type => $config_names) {
        if (empty($config_names)) {
          continue;
        }

        // @todo A table caption would be more appropriate, but does not have the
        //   visual importance of a heading.
        $form[$collection][$config_change_type]['heading'] = [
          '#type' => 'html_tag',
          '#tag' => 'h3',
        ];
        switch ($config_change_type) {
          case 'create':
            $form[$collection][$config_change_type]['heading']['#value'] = $this
              ->formatPlural(count($config_names), '@count new', '@count new');
            break;
          case 'update':
            $form[$collection][$config_change_type]['heading']['#value'] = $this
              ->formatPlural(count($config_names), '@count changed', '@count changed');
            break;
          case 'delete':
            $form[$collection][$config_change_type]['heading']['#value'] = $this
              ->formatPlural(count($config_names), '@count removed', '@count removed');
            break;
          case 'rename':
            $form[$collection][$config_change_type]['heading']['#value'] = $this
              ->formatPlural(count($config_names), '@count renamed', '@count renamed');
            break;
        }
        $form[$collection][$config_change_type]['list'] = [
          '#type' => 'table',
          '#header' => [
            $this
              ->t('Name'),
            $this
              ->t('Operations'),
          ],
        ];
        foreach ($config_names as $config_name) {
          $route_options = $options['route'];
          if ($config_change_type == 'rename') {
            $names = $storage_comparer
              ->extractRenameNames($config_name);
            $route_options['source_name'] = $names['old_name'];
            $route_options['target_name'] = $names['new_name'];
            $config_name = $this
              ->t('@source_name to @target_name', [
              '@source_name' => $names['old_name'],
              '@target_name' => $names['new_name'],
            ]);
          }
          else {
            $route_options['source_name'] = $config_name;
          }
          if ($collection != StorageInterface::DEFAULT_COLLECTION) {
            $route_name = 'config_split.diff_collection';
            $route_options['collection'] = $collection;
          }
          else {
            $route_name = 'config_split.diff';
          }
          $links['view_diff'] = [
            'title' => $this
              ->t('View differences'),
            'url' => Url::fromRoute($route_name, $route_options),
            'attributes' => [
              'class' => [
                'use-ajax',
              ],
              'data-dialog-type' => 'modal',
              'data-dialog-options' => json_encode([
                'width' => 700,
              ]),
            ],
          ];
          $form[$collection][$config_change_type]['list']['#rows'][] = [
            'name' => $config_name,
            'operations' => [
              'data' => [
                '#type' => 'operations',
                '#links' => $links,
              ],
            ],
          ];
        }
      }
    }
    return $form;
  }

  /**
   * {@inheritdoc}
   */
  protected function launchImport(StorageComparerInterface $comparer) {
    $config_importer = $this
      ->getConfigImporterFromComparer($comparer);
    if ($config_importer
      ->alreadyImporting()) {
      $this
        ->messenger()
        ->addStatus($this
        ->t('Another request may be synchronizing configuration already.'));
    }
    else {
      try {
        $sync_steps = $config_importer
          ->initialize();
        $batch = [
          'operations' => [],
          'finished' => [
            self::class,
            'finishImportBatch',
          ],
          'title' => t('Synchronizing configuration'),
          'init_message' => t('Starting configuration synchronization.'),
          'progress_message' => t('Completed step @current of @total.'),
          'error_message' => t('Configuration synchronization has encountered an error.'),
        ];
        foreach ($sync_steps as $sync_step) {
          $batch['operations'][] = [
            [
              ConfigImporterBatch::class,
              'process',
            ],
            [
              $config_importer,
              $sync_step,
            ],
          ];
        }
        batch_set($batch);
      } catch (ConfigImporterException $e) {

        // There are validation errors.
        $this
          ->messenger()
          ->addError($this
          ->t('The configuration cannot be imported because it failed validation for the following reasons:'));
        foreach ($config_importer
          ->getErrors() as $message) {
          $this
            ->messenger()
            ->addError($message);
        }
      }
    }
  }

  /**
   * {@inheritdoc}
   */
  public static function finishImportBatch($success, $results, $operations) {
    ConfigImporterBatch::finish($success, $results, $operations);
    if ($success) {
      return new RedirectResponse(Url::fromRoute('entity.config_split.collection', [], [
        'absolute' => TRUE,
      ])
        ->toString(), 302);
    }
  }

  /**
   * Get a split from the route.
   *
   * @return \Drupal\Core\Config\ImmutableConfig
   *   The split config.
   */
  protected function getSplit() {
    $split = $this->manager
      ->getSplitConfig($this
      ->getRouteMatch()
      ->getRawParameter('config_split'));
    if ($split === NULL) {
      throw new \UnexpectedValueException("Unknown split");
    }
    return $split;
  }

}