class ConfigSingleImportForm

class ConfigSingleImportForm extends ConfirmFormBase {
    
    /**
     * The entity type manager.
     *
     * @var \Drupal\Core\Entity\EntityTypeManagerInterface
     */
    protected $entityTypeManager;
    
    /**
     * The config storage.
     *
     * @var \Drupal\Core\Config\StorageInterface
     */
    protected $configStorage;
    
    /**
     * The renderer service.
     *
     * @var \Drupal\Core\Render\RendererInterface
     */
    protected $renderer;
    
    /**
     * The event dispatcher.
     *
     * @var \Symfony\Contracts\EventDispatcher\EventDispatcherInterface
     */
    protected $eventDispatcher;
    
    /**
     * The configuration manager.
     *
     * @var \Drupal\Core\Config\ConfigManagerInterface
     */
    protected $configManager;
    
    /**
     * The database lock object.
     *
     * @var \Drupal\Core\Lock\LockBackendInterface
     */
    protected $lock;
    
    /**
     * The typed config manager.
     *
     * @var \Drupal\Core\Config\TypedConfigManagerInterface
     */
    protected $typedConfigManager;
    
    /**
     * The module handler.
     *
     * @var \Drupal\Core\Extension\ModuleHandlerInterface
     */
    protected $moduleHandler;
    
    /**
     * The theme handler.
     *
     * @var \Drupal\Core\Extension\ThemeHandlerInterface
     */
    protected $themeHandler;
    
    /**
     * The module extension list.
     *
     * @var \Drupal\Core\Extension\ModuleExtensionList
     */
    protected $moduleExtensionList;
    
    /**
     * The theme extension list.
     *
     * @var \Drupal\Core\Extension\ThemeExtensionList
     */
    protected $themeExtensionList;
    
    /**
     * The module installer.
     *
     * @var \Drupal\Core\Extension\ModuleInstallerInterface
     */
    protected $moduleInstaller;
    
    /**
     * If the config exists, this is that object. Otherwise, FALSE.
     *
     * @var \Drupal\Core\Config\Config|\Drupal\Core\Config\Entity\ConfigEntityInterface|bool
     */
    protected $configExists = FALSE;
    
    /**
     * The submitted data needing to be confirmed.
     *
     * @var array
     */
    protected $data = [];
    
    /**
     * Constructs a new ConfigSingleImportForm.
     *
     * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
     *   The entity type manager.
     * @param \Drupal\Core\Config\StorageInterface $config_storage
     *   The config storage.
     * @param \Drupal\Core\Render\RendererInterface $renderer
     *   The renderer service.
     * @param \Symfony\Contracts\EventDispatcher\EventDispatcherInterface $event_dispatcher
     *   The event dispatcher used to notify subscribers of config import events.
     * @param \Drupal\Core\Config\ConfigManagerInterface $config_manager
     *   The configuration manager.
     * @param \Drupal\Core\Lock\LockBackendInterface $lock
     *   The lock backend to ensure multiple imports do not occur at the same time.
     * @param \Drupal\Core\Config\TypedConfigManagerInterface $typed_config
     *   The typed configuration manager.
     * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
     *   The module handler.
     * @param \Drupal\Core\Extension\ModuleInstallerInterface $module_installer
     *   The module installer.
     * @param \Drupal\Core\Extension\ThemeHandlerInterface $theme_handler
     *   The theme handler.
     * @param \Drupal\Core\Extension\ModuleExtensionList $extension_list_module
     *   The module extension list.
     * @param \Drupal\Core\Extension\ThemeExtensionList $extension_list_theme
     *   The theme extension list.
     */
    public function __construct(EntityTypeManagerInterface $entity_type_manager, StorageInterface $config_storage, RendererInterface $renderer, EventDispatcherInterface $event_dispatcher, ConfigManagerInterface $config_manager, LockBackendInterface $lock, TypedConfigManagerInterface $typed_config, ModuleHandlerInterface $module_handler, ModuleInstallerInterface $module_installer, ThemeHandlerInterface $theme_handler, ModuleExtensionList $extension_list_module, ThemeExtensionList $extension_list_theme = NULL) {
        $this->entityTypeManager = $entity_type_manager;
        $this->configStorage = $config_storage;
        $this->renderer = $renderer;
        // Services necessary for \Drupal\Core\Config\ConfigImporter.
        $this->eventDispatcher = $event_dispatcher;
        $this->configManager = $config_manager;
        $this->lock = $lock;
        $this->typedConfigManager = $typed_config;
        $this->moduleHandler = $module_handler;
        $this->moduleInstaller = $module_installer;
        $this->themeHandler = $theme_handler;
        $this->moduleExtensionList = $extension_list_module;
        if ($extension_list_theme === NULL) {
            $extension_list_theme = \Drupal::service('extension.list.theme');
        }
        $this->themeExtensionList = $extension_list_theme;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('entity_type.manager'), $container->get('config.storage'), $container->get('renderer'), $container->get('event_dispatcher'), $container->get('config.manager'), $container->get('lock.persistent'), $container->get('config.typed'), $container->get('module_handler'), $container->get('module_installer'), $container->get('theme_handler'), $container->get('extension.list.module'), $container->get('extension.list.theme'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'config_single_import_form';
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCancelUrl() {
        return new Url('config.import_single');
    }
    
    /**
     * {@inheritdoc}
     */
    public function getQuestion() {
        if ($this->data['config_type'] === 'system.simple') {
            $name = $this->data['config_name'];
            $type = $this->t('simple configuration');
        }
        else {
            $definition = $this->entityTypeManager
                ->getDefinition($this->data['config_type']);
            $name = $this->data['import'][$definition->getKey('id')];
            $type = $definition->getSingularLabel();
        }
        $args = [
            '%name' => $name,
            '@type' => strtolower($type),
        ];
        if ($this->configExists) {
            $question = $this->t('Are you sure you want to update the %name @type?', $args);
        }
        else {
            $question = $this->t('Are you sure you want to create a new %name @type?', $args);
        }
        return $question;
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        // When this is the confirmation step fall through to the confirmation form.
        if ($this->data) {
            return parent::buildForm($form, $form_state);
        }
        $entity_types = [];
        foreach ($this->entityTypeManager
            ->getDefinitions() as $entity_type => $definition) {
            if ($definition->entityClassImplements(ConfigEntityInterface::class)) {
                $entity_types[$entity_type] = $definition->getLabel();
            }
        }
        // Sort the entity types by label, then add the simple config to the top.
        uasort($entity_types, 'strnatcasecmp');
        $config_types = [
            'system.simple' => $this->t('Simple configuration'),
        ] + $entity_types;
        $form['config_type'] = [
            '#title' => $this->t('Configuration type'),
            '#type' => 'select',
            '#options' => $config_types,
            '#required' => TRUE,
        ];
        $form['config_name'] = [
            '#title' => $this->t('Configuration name'),
            '#description' => $this->t('Enter the name of the configuration file without the <em>.yml</em> extension. (e.g. <em>system.site</em>)'),
            '#type' => 'textfield',
            '#states' => [
                'required' => [
                    ':input[name="config_type"]' => [
                        'value' => 'system.simple',
                    ],
                ],
                'visible' => [
                    ':input[name="config_type"]' => [
                        'value' => 'system.simple',
                    ],
                ],
            ],
        ];
        $form['import'] = [
            '#title' => $this->t('Paste your configuration here'),
            '#type' => 'textarea',
            '#rows' => 24,
            '#required' => TRUE,
        ];
        $form['advanced'] = [
            '#type' => 'details',
            '#title' => $this->t('Advanced'),
        ];
        $form['advanced']['custom_entity_id'] = [
            '#title' => $this->t('Custom Entity ID'),
            '#type' => 'textfield',
            '#description' => $this->t('Specify a custom entity ID. This will override the entity ID in the configuration above.'),
        ];
        $form['actions'] = [
            '#type' => 'actions',
        ];
        $form['actions']['submit'] = [
            '#type' => 'submit',
            '#value' => $this->t('Import'),
            '#button_type' => 'primary',
        ];
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function validateForm(array &$form, FormStateInterface $form_state) {
        // The confirmation step needs no additional validation.
        if ($this->data) {
            return;
        }
        try {
            // Decode the submitted import.
            $data = Yaml::decode($form_state->getValue('import'));
        } catch (InvalidDataTypeException $e) {
            $form_state->setErrorByName('import', $this->t('The import failed with the following message: %message', [
                '%message' => $e->getMessage(),
            ]));
        }
        // Validate for config entities.
        if ($form_state->getValue('config_type') && $form_state->getValue('config_type') !== 'system.simple') {
            $definition = $this->entityTypeManager
                ->getDefinition($form_state->getValue('config_type'));
            $id_key = $definition->getKey('id');
            // If a custom entity ID is specified, override the value in the
            // configuration data being imported.
            if (!$form_state->isValueEmpty('custom_entity_id')) {
                $data[$id_key] = $form_state->getValue('custom_entity_id');
            }
            $entity_storage = $this->entityTypeManager
                ->getStorage($form_state->getValue('config_type'));
            // If an entity ID was not specified, set an error.
            if (!isset($data[$id_key])) {
                $form_state->setErrorByName('import', $this->t('Missing ID key "@id_key" for this @entity_type import.', [
                    '@id_key' => $id_key,
                    '@entity_type' => $definition->getLabel(),
                ]));
                return;
            }
            $config_name = $definition->getConfigPrefix() . '.' . $data[$id_key];
            // If there is an existing entity, ensure matching ID and UUID.
            if ($entity = $entity_storage->load($data[$id_key])) {
                $this->configExists = $entity;
                if (!isset($data['uuid'])) {
                    $form_state->setErrorByName('import', $this->t('An entity with this machine name already exists but the import did not specify a UUID.'));
                    return;
                }
                if ($data['uuid'] !== $entity->uuid()) {
                    $form_state->setErrorByName('import', $this->t('An entity with this machine name already exists but the UUID does not match.'));
                    return;
                }
            }
            elseif (isset($data['uuid']) && $entity_storage->loadByProperties([
                'uuid' => $data['uuid'],
            ])) {
                $form_state->setErrorByName('import', $this->t('An entity with this UUID already exists but the machine name does not match.'));
            }
        }
        else {
            $config_name = $form_state->getValue('config_name');
            $config = $this->config($config_name);
            $this->configExists = !$config->isNew() ? $config : FALSE;
        }
        // Use ConfigImporter validation.
        if (!$form_state->getErrors()) {
            $source_storage = new StorageReplaceDataWrapper($this->configStorage);
            $source_storage->replaceData($config_name, $data);
            $storage_comparer = new StorageComparer($source_storage, $this->configStorage);
            $storage_comparer->createChangelist();
            if (!$storage_comparer->hasChanges()) {
                $form_state->setErrorByName('import', $this->t('There are no changes to import.'));
            }
            else {
                $config_importer = new ConfigImporter($storage_comparer, $this->eventDispatcher, $this->configManager, $this->lock, $this->typedConfigManager, $this->moduleHandler, $this->moduleInstaller, $this->themeHandler, $this->getStringTranslation(), $this->moduleExtensionList, $this->themeExtensionList);
                try {
                    $config_importer->validate();
                    $form_state->set('config_importer', $config_importer);
                } catch (ConfigImporterException $e) {
                    // There are validation errors.
                    $item_list = [
                        '#theme' => 'item_list',
                        '#items' => $config_importer->getErrors(),
                        '#title' => $this->t('The configuration cannot be imported because it failed validation for the following reasons:'),
                    ];
                    $form_state->setErrorByName('import', $this->renderer
                        ->render($item_list));
                }
            }
        }
        // Store the decoded version of the submitted import.
        $form_state->setValueForElement($form['import'], $data);
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        // If this form has not yet been confirmed, store the values and rebuild.
        if (!$this->data) {
            $form_state->setRebuild();
            $this->data = $form_state->getValues();
            return;
        }
        
        /** @var \Drupal\Core\Config\ConfigImporter $config_importer */
        $config_importer = $form_state->get('config_importer');
        if ($config_importer->alreadyImporting()) {
            $this->messenger()
                ->addError($this->t('Another request may be importing configuration already.'));
        }
        else {
            try {
                $sync_steps = $config_importer->initialize();
                $batch_builder = (new BatchBuilder())->setTitle($this->t('Importing configuration'))
                    ->setFinishCallback([
                    ConfigImporterBatch::class,
                    'finish',
                ])
                    ->setInitMessage($this->t('Starting configuration import.'))
                    ->setProgressMessage($this->t('Completed @current step of @total.'))
                    ->setErrorMessage($this->t('Configuration import has encountered an error.'));
                foreach ($sync_steps as $sync_step) {
                    $batch_builder->addOperation([
                        ConfigImporterBatch::class,
                        'process',
                    ], [
                        $config_importer,
                        $sync_step,
                    ]);
                }
                batch_set($batch_builder->toArray());
            } catch (ConfigImporterException $e) {
                // There are validation errors.
                $this->messenger()
                    ->addError($this->t('The configuration import failed for the following reasons:'));
                foreach ($config_importer->getErrors() as $message) {
                    $this->messenger()
                        ->addError($message);
                }
            }
        }
    }

}