class FieldStateManager

class FieldStateManager extends DefaultPluginManager {
    
    /**
     * LoggerInterface.
     *
     * @var \Psr\Log\LoggerInterface
     */
    private $logger;
    
    /**
     * Constructs a new FieldStateManager.
     *
     * @param \Traversable $namespaces
     *   An object that implements \Traversable which contains the root paths
     *   keyed by the corresponding namespace to look for plugin implementations.
     * @param \Drupal\Core\Cache\CacheBackendInterface $cache_backend
     *   Cache backend instance to use.
     * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
     *   The module handler.
     * @param \Psr\Log\LoggerInterface $logger
     *   The logger.
     */
    public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler, LoggerInterface $logger) {
        parent::__construct('Plugin/FieldState', $namespaces, $module_handler, 'Drupal\\field_states_ui\\FieldStateInterface', 'Drupal\\field_states_ui\\Annotation\\FieldState');
        $this->alterInfo('field_state_info');
        $this->setCacheBackend($cache_backend, 'field_state_plugins');
        $this->logger = $logger;
    }
    
    /**
     * Apply the field states to a form element.
     *
     * Due to various form elements having different array structure, the states
     * array has to be put in a different spot for different widgets. Most common
     * locations are `value` and `target_id` or for multiple value forms, on the
     * wrapper.
     *
     * @param array $element
     *   The field widget form elements as constructed by
     *   \Drupal\Core\Field\WidgetBase::formMultipleElements().
     * @param \Drupal\Core\Form\FormStateInterface $form_state
     *   The current state of the form.
     * @param array $context
     *   An associative array containing the following key-value pairs:
     *   - form: The form structure to which widgets are being attached. This may be
     *     a full form structure, or a sub-element of a larger form.
     *   - widget: The widget plugin instance.
     *   - items: The field values, as a
     *     \Drupal\Core\Field\FieldItemListInterface object.
     *   - default: A boolean indicating whether the form is being shown as a dummy
     *     form to set default values.
     *
     * @see hook_field_widget_multivalue_form_alter().
     */
    public function apply(&$element, FormStateInterface $form_state, $context) {
        
        /** @var \Drupal\Core\Field\PluginSettingsInterface $plugin */
        $plugin = $context['widget'];
        // Check that it is enabled for this field.
        if (empty($plugin->getThirdPartySettings('field_states_ui')['field_states'])) {
            return;
        }
        $states = $plugin->getThirdPartySettings('field_states_ui')['field_states'];
        
        /** @var \Drupal\Core\Field\FieldItemListInterface $field_item */
        $field_item = $context['items'];
        $field_definition = $field_item->getFieldDefinition();
        $type = $field_definition->getType();
        $plugin_id = $plugin->getPluginId();
        // Handle the type of field appropriately.
        switch ($type) {
            case 'entity_reference':
                switch ($plugin_id) {
                    case 'chosen_select':
                    case 'options_select':
                    case 'options_buttons':
                    case 'media_library_widget':
                        $target =& $element;
                        break;
                    case 'entity_browser_entity_reference':
                        if (!isset($element[0])) {
                            $target =& $element;
                        }
                        else {
                            $target =& $element[0];
                        }
                        break;
                    case 'entity_reference_autocomplete':
                    case 'entity_reference_autocomplete_tags':
                        if (!isset($element[0])) {
                            $target =& $element['target_id'];
                        }
                        else {
                            $target =& $element[0]['target_id'];
                        }
                        break;
                    default:
                        // Log a notice so that user(s) can report unrecognized field
                        // plugin_id.
                        $this->logger
                            ->notice(t('Field type: "@type" with plugin_id "@id" was unrecognized. Please report on the @link. For quickest resolution, please include what module it comes from.', [
                            '@type' => $type,
                            '@id' => $plugin_id,
                            '@link' => Link::fromTextAndUrl(t('Field States UI Issue Queue'), Url::fromUri('https://www.drupal.org/project/issues/field_states_ui'))->toString(),
                        ]));
                        if (isset($element[0]['target_id'])) {
                            $target =& $element[0]['target_id'];
                        }
                        elseif (isset($element['target_id'])) {
                            $target =& $element['target_id'];
                        }
                        else {
                            $target =& $element;
                        }
                        break;
                }
                break;
            case 'boolean':
                switch ($plugin_id) {
                    case 'options_buttons':
                        $target =& $element[0];
                        break;
                    case 'boolean_checkbox':
                        $target =& $element['value'];
                        break;
                    default:
                        $target =& $element[0]['value'];
                        break;
                }
                break;
            case 'address_country':
            case 'decimal':
            case 'float':
            case 'integer':
            case 'string':
            case 'string_long':
                $target =& $element[0]['value'];
                break;
            case 'text_with_summary':
            case 'text_long':
            case 'list_float':
            case 'list_integer':
            case 'list_string':
            case 'link':
            case 'entity_reference_revisions':
            case 'datetime':
            case 'color_field_type':
            case 'address_zone':
            case 'address':
                if (!isset($element[0])) {
                    $target =& $element;
                }
                else {
                    $target =& $element[0];
                }
                break;
            case 'name':
                $target =& $element[0];
                $container = TRUE;
                break;
            default:
                // Log a notice so that user(s) can report unrecognized field types.
                $this->logger
                    ->notice(t('Field type: "@type" was unrecognized. Please report on the @link. For quickest resolution, please include the element details: @details', [
                    '@type' => $type,
                    '@link' => Link::fromTextAndUrl(t('Field States UI Issue Queue'), Url::fromUri('https://www.drupal.org/project/issues/field_states_ui'))->toString(),
                    '@details' => var_export(array_keys($element[0]), TRUE),
                ]));
                $target =& $element[0];
                $container = TRUE;
                break;
        }
        if (!isset($target['#field_parents'])) {
            $parents = [];
            $this->logger
                ->notice(t('#field_parents key not found. This will may cause problems. If so, please report on the @link. For quickest resolution, please include the element details: @details', [
                '@link' => Link::fromTextAndUrl(t('Field States UI Issue Queue'), Url::fromUri('https://www.drupal.org/project/issues/field_states_ui'))->toString(),
                '@details' => var_export(array_keys($element[0]), TRUE),
            ]));
        }
        else {
            $parents = $target['#field_parents'];
        }
        if (isset($element['#cardinality_multiple']) && $element['#cardinality_multiple']) {
            // Multiple widget field. Put states on the wrapper.
            $element = [
                'element' => $element,
                '#type' => 'container',
                '#states' => $this->getStates($states, $form_state, $context, $element, $parents),
            ];
        }
        elseif (isset($container)) {
            // Add a container element and set states on that to ensure it works.
            // This increases divitis which is already common on Drupal forms so
            // it is better to handle the element properly. There are elements that it
            // does make sense to do this to (ie name) but avoid if possible.
            $element = [
                'element' => $element,
                '#type' => 'container',
                '#states' => $this->getStates($states, $form_state, $context, $element, $parents),
            ];
        }
        else {
            $target['#states'] = $this->getStates($states, $form_state, $context, $element, $parents);
        }
    }
    
    /**
     * Returns the field states for a given element.
     *
     * @param array[] $field_states
     *   An array of field state configuration.
     * @param \Drupal\Core\Form\FormStateInterface $form_state
     *   Provides an interface for an object containing the current state of a form.
     * @param array $context
     *   An associative array containing the following key-value pairs:
     *   - form: The form structure to which widgets are being attached. This may be
     *     a full form structure, or a sub-element of a larger form.
     *   - widget: The widget plugin instance.
     *   - items: The field values, as a
     *     \Drupal\Core\Field\FieldItemListInterface object.
     *   - delta: The order of this item in the array of subelements (0, 1, 2, etc).
     *   - default: A boolean indicating whether the form is being shown as a dummy
     *     form to set default values.
     * @param array $element
     *   The field widget form element as constructed by
     *   \Drupal\Core\Field\WidgetBaseInterface::form().
     * @param array $parents
     *   The current element's parents in the form.
     *
     * @return array
     *   An array of states to render.
     */
    protected function getStates(array $field_states, FormStateInterface $form_state, array $context, array $element, array $parents) {
        $states = [];
        foreach ($field_states as $state) {
            if (!isset($state['id'])) {
                continue;
            }
            try {
                
                /** @var \Drupal\field_states_ui\FieldStateInterface $field_state */
                $field_state = $this->createInstance($state['id'], $state);
            } catch (\Exception $exception) {
                continue;
            }
            $field_state->applyState($states, $form_state, $context, $element, $parents);
        }
        return $states;
    }
    
    /**
     * Implements hook_field_widget_third_party_settings_form().
     */
    public function settingsForm(WidgetInterface $plugin, FieldDefinitionInterface $field_definition, $form_mode, $form, FormStateInterface $form_state) {
        $field_name = $field_definition->getName();
        $element = [
            'form' => [
                '#type' => 'fieldset',
                '#title' => t('Manage Field States'),
                '#description' => t('Configure field states - ie automatic hiding/showing of fields.'),
                'list' => [
                    '#type' => 'table',
                    '#header' => [
                        t('Type'),
                        t('Comparison'),
                        t('Operations'),
                    ],
                    '#empty' => t('There are no field states applied to this field currently. Add one by selecting an option below.'),
                ],
            ],
        ];
        $cancel = [
            '#type' => 'submit',
            '#value' => t('Cancel'),
            '#submit' => [
                [
                    self::class,
                    'settingsSubmit',
                ],
            ],
            '#field_name' => $field_name,
            '#limit_validation_errors' => [],
            '#op' => 'cancel',
        ];
        // Display and maintain existing form states with edit options.
        $field_states_settings = $plugin->getThirdPartySettings('field_states_ui');
        if (!empty($field_states_settings['field_states'])) {
            $element['field_states'] = [];
            foreach ($field_states_settings['field_states'] as $key => $state) {
                if (!isset($state['id'])) {
                    continue;
                }
                $field_state = $this->createInstance($state['id'], $state);
                $element['form']['list'][$key] = [
                    'type' => [
                        '#type' => 'markup',
                        '#markup' => $field_state->label(),
                    ],
                    'comparison' => $field_state->getSummary(),
                    'operations' => [
                        'edit' => [
                            '#type' => 'submit',
                            '#value' => t('Edit'),
                            '#op' => 'edit',
                            '#submit' => [
                                [
                                    self::class,
                                    'settingsSubmit',
                                ],
                            ],
                            '#field_name' => $field_name,
                            '#key' => $key,
                            '#name' => 'edit-' . $key,
                        ],
                        'delete' => [
                            '#type' => 'submit',
                            '#value' => t('Delete'),
                            '#op' => 'delete',
                            '#submit' => [
                                [
                                    self::class,
                                    'settingsSubmit',
                                ],
                            ],
                            '#field_name' => $field_name,
                            '#key' => $key,
                            '#name' => 'delete-' . $key,
                        ],
                    ],
                ];
                $element['field_states'][$field_state->getUuid()] = [
                    'uuid' => [
                        '#type' => 'hidden',
                        '#value' => $field_state->getUuid(),
                    ],
                    'id' => [
                        '#type' => 'hidden',
                        '#value' => $field_state->getPluginId(),
                    ],
                    'data' => $field_state->getConfigurationForForm(),
                ];
            }
        }
        // Provide form elements to edit/add form states.
        if ($form_state->get('field_states_ui_edit') == $field_name) {
            if ($form_state->get('field_states_ui_target')) {
                $target = $form_state->get('field_states_ui_target');
                $states = $plugin->getThirdPartySettings('field_states_ui')['field_states'];
                if (!isset($states[$target])) {
                    return $element;
                }
                $type = $states[$target]['id'];
                $field_state = $this->createInstance($type, $states[$target]);
                $title = t('Edit field state: @type', [
                    '@type' => $field_state->label(),
                ]);
                $submit_label = t('Update State');
                $op = 'process_update';
            }
            else {
                $type = $form_state->getValue([
                    'fields',
                    $field_name,
                    'settings_edit_form',
                    'third_party_settings',
                    'field_states_ui',
                    'form',
                    'type',
                ]);
                $field_state = $this->createInstance($type);
                $title = t('Add new field state: @type', [
                    '@type' => $field_state->label(),
                ]);
                $submit_label = t('Add');
                $op = 'new';
            }
            $element['form']['edit'] = $field_state->buildConfigurationForm([], $form_state);
            $element['form']['edit']['#type'] = 'fieldset';
            $element['form']['edit']['#title'] = $title;
            $element['form']['edit']['submit'] = [
                'save' => [
                    '#type' => 'submit',
                    '#value' => $submit_label,
                    '#validate' => [
                        [
                            self::class,
                            'settingsValidate',
                        ],
                    ],
                    '#submit' => [
                        [
                            self::class,
                            'settingsSubmit',
                        ],
                    ],
                    '#field_name' => $field_name,
                    '#op' => $op,
                    '#plugin' => $type,
                ],
                'cancel' => $cancel,
            ];
        }
        elseif ($form_state->get('field_states_ui_edit') == 'delete') {
            $element['form']['delete'] = [
                '#type' => 'fieldset',
                '#tree' => FALSE,
                '#title' => t('Delete field state?'),
                'delete_submit' => [
                    '#type' => 'submit',
                    '#value' => t('Confirm Delete'),
                    '#submit' => [
                        [
                            self::class,
                            'settingsSubmit',
                        ],
                    ],
                    '#target' => $form_state->get('field_states_ui_target'),
                    '#op' => 'process_delete',
                    '#field_name' => $field_name,
                ],
                'cancel' => $cancel,
            ];
        }
        else {
            $field_state_options = [];
            $field_states = $this->getDefinitions();
            foreach ($field_states as $field_state => $definition) {
                $field_state_options[$field_state] = $definition['label'];
            }
            $element['form']['type'] = [
                '#type' => 'select',
                '#title' => t('Field States'),
                '#title_display' => 'invisible',
                '#options' => $field_state_options,
                '#empty_option' => t('Select a new field state'),
            ];
            $element['form']['add'] = [
                '#type' => 'submit',
                '#value' => t('Add'),
                '#validate' => [
                    [
                        self::class,
                        'settingsValidate',
                    ],
                ],
                '#submit' => [
                    [
                        self::class,
                        'settingsSubmit',
                    ],
                ],
                '#field_name' => $field_name,
                '#op' => 'add',
            ];
        }
        return $element;
    }
    
    /**
     * Submit function to add/edit field states.
     *
     * @param array $form
     *   The whole EntityFormDisplay form array
     * @param \Drupal\Core\Form\FormStateInterface $form_state
     *   The form state.
     */
    public static function settingsSubmit(array $form, FormStateInterface $form_state) {
        $trigger = $form_state->getTriggeringElement();
        $field_name = $trigger['#field_name'];
        $form_state->set('plugin_settings_edit', $field_name);
        
        /** @var \Drupal\Core\Entity\EntityFormInterface $form_object */
        $form_object = $form_state->getFormObject();
        
        /** @var \Drupal\Core\Entity\Entity\EntityFormDisplay $entity */
        $entity = $form_object->getEntity();
        // Show the add new field state form for the specified field state type.
        if ($trigger['#op'] == 'add') {
            $form_state->set('field_states_ui_edit', $field_name);
        }
        elseif ($trigger['#op'] == 'cancel') {
            $form_state->set('field_states_ui_edit', NULL);
            $form_state->set('field_states_ui_target', NULL);
        }
        elseif ($trigger['#op'] == 'edit') {
            $form_state->set('field_states_ui_edit', $field_name);
            $form_state->set('field_states_ui_target', $trigger['#key']);
        }
        elseif ($trigger['#op'] == 'delete') {
            $form_state->set('field_states_ui_edit', 'delete');
            $form_state->set('field_states_ui_target', $trigger['#key']);
        }
        elseif ($trigger['#op'] == 'process_delete') {
            $field = $entity->getComponent($field_name);
            unset($field['third_party_settings']['field_states_ui']['field_states'][$form_state->get('field_states_ui_target')]);
            $entity->setComponent($field_name, $field);
            $entity->save();
            $form_state->set('field_states_ui_edit', NULL);
            $form_state->set('field_states_ui_target', NULL);
        }
        elseif ($trigger['#op'] == 'new') {
            $field = $entity->getComponent($field_name);
            $field_state = self::getManager()->createInstance($trigger['#plugin']);
            $field_state_data = $form_state->getValue([
                'fields',
                $field_name,
                'settings_edit_form',
                'third_party_settings',
                'field_states_ui',
                'form',
                'edit',
            ]);
            $field_state->submitConfigurationForm($form, (new FormState())->setValues($field_state_data));
            $field['third_party_settings']['field_states_ui']['field_states'][$field_state->getUuid()] = $field_state->getConfiguration();
            $entity->setComponent($field_name, $field);
            $entity->save();
            $form_state->set('field_states_ui_edit', NULL);
        }
        elseif ($trigger['#op'] == 'process_update') {
            $field = $entity->getComponent($field_name);
            $target = $form_state->get('field_states_ui_target');
            $field_state = self::getManager()->createInstance($trigger['#plugin'], $field['third_party_settings']['field_states_ui']['field_states'][$target]);
            $field_state_data = $form_state->getValue([
                'fields',
                $field_name,
                'settings_edit_form',
                'third_party_settings',
                'field_states_ui',
                'form',
                'edit',
            ]);
            $field_state->submitConfigurationForm($form, (new FormState())->setValues($field_state_data));
            $field['third_party_settings']['field_states_ui']['field_states'][$field_state->getUuid()] = $field_state->getConfiguration();
            $entity->setComponent($field_name, $field);
            $entity->save();
            $form_state->set('field_states_ui_edit', NULL);
            $form_state->set('field_states_ui_target', NULL);
        }
        $form_state->setRebuild();
    }
    
    /**
     * Validation function for adding/editing field states.
     *
     * @param array $form
     *   The whole EntityFormDisplay form array
     * @param \Drupal\Core\Form\FormStateInterface $form_state
     *   The form state.
     */
    public static function settingsValidate(array $form, FormStateInterface $form_state) {
        $trigger = $form_state->getTriggeringElement();
        $field_name = $trigger['#field_name'];
        $op = $trigger['#op'];
        if ($op == 'add') {
            $element = "fields][{$field_name}][settings_edit_form][third_party_settings][field_states_ui][form][type";
            $type = $form_state->getValue([
                'fields',
                $field_name,
                'settings_edit_form',
                'third_party_settings',
                'field_states_ui',
                'form',
                'type',
            ]);
            if (!$type) {
                $form_state->setErrorByName($element, t('You must select a field state to add.'));
            }
        }
    }
    protected static function getManager() {
        return \Drupal::service('plugin.manager.field_states_ui.fieldstate');
    }

}