<?php

namespace Drupal\layout_builder\Element;

use Drupal\Component\Utility\Html;
use Drupal\Component\Utility\NestedArray;
use Drupal\Core\Ajax\AjaxHelperTrait;
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
use Drupal\Core\Plugin\PluginFormInterface;
use Drupal\Core\Render\Attribute\RenderElement;
use Drupal\Core\Render\Element;
use Drupal\Core\Render\Element\RenderElementBase;
use Drupal\Core\Security\Attribute\TrustedCallback;
use Drupal\Core\Url;
use Drupal\layout_builder\Context\LayoutBuilderContextTrait;
use Drupal\layout_builder\Event\PrepareLayoutEvent;
use Drupal\layout_builder\LayoutBuilderEvents;
use Drupal\layout_builder\LayoutBuilderHighlightTrait;
use Drupal\layout_builder\SectionStorageInterface;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Symfony\Contracts\EventDispatcher\EventDispatcherInterface;

/**
 * Defines a render element for building the Layout Builder UI.
 *
 * @internal
 *   Plugin classes are internal.
 */
#[RenderElement('layout_builder')]
class LayoutBuilder extends RenderElementBase implements ContainerFactoryPluginInterface {

  use AjaxHelperTrait;
  use LayoutBuilderContextTrait;
  use LayoutBuilderHighlightTrait;

  /**
   * The event dispatcher.
   *
   * @var \Symfony\Contracts\EventDispatcher\EventDispatcherInterface
   */
  protected $eventDispatcher;

  /**
   * Constructs a new LayoutBuilder.
   *
   * @param array $configuration
   *   A configuration array containing information about the plugin instance.
   * @param string $plugin_id
   *   The plugin ID for the plugin instance.
   * @param mixed $plugin_definition
   *   The plugin implementation definition.
   * @param \Symfony\Contracts\EventDispatcher\EventDispatcherInterface $event_dispatcher
   *   The event dispatcher service.
   */
  public function __construct(array $configuration, $plugin_id, $plugin_definition, EventDispatcherInterface $event_dispatcher) {
    parent::__construct($configuration, $plugin_id, $plugin_definition);
    $this->eventDispatcher = $event_dispatcher;
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
    return new static(
      $configuration,
      $plugin_id,
      $plugin_definition,
      $container->get('event_dispatcher')
    );
  }

  /**
   * {@inheritdoc}
   */
  public function getInfo() {
    return [
      '#section_storage' => NULL,
      '#pre_render' => [
        [$this, 'preRender'],
      ],
      '#process' => [
        [static::class, 'layoutBuilderElementGetKeys'],
      ],
    ];
  }

  /**
   * Form element #process callback.
   *
   * Save the layout builder element array parents as a property on the top form
   * element, so that they can be used to access the element within the form
   * render array later.
   *
   * @param array $element
   *   The render array for the layout builder element.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   Form state object.
   * @param array $form
   *   The render array for the complete form.
   *
   * @return array
   *   The layout builder element render array after processing.
   *
   * @see \Drupal\layout_builder\Controller\LayoutBuilderHtmlEntityFormController
   */
  public static function layoutBuilderElementGetKeys(array $element, FormStateInterface $form_state, array &$form): array {
    $form['#layout_builder_element_keys'] = $element['#array_parents'];
    $form['#pre_render'][] = [static::class, 'renderLayoutBuilderAfterForm'];
    $form['#post_render'][] = [static::class, 'addRenderedLayoutBuilder'];
    return $element;
  }

  /**
   * Render API #pre_render callback for form containing layout builder element.
   *
   * Because the layout builder element can contain components with forms, it
   * needs to exist outside forms within the DOM, to avoid nested form tags.
   * The layout builder element is rendered to markup here and saved, and later
   * the saved markup will be appended after the form markup.
   *
   * @param array $form
   *   The rendered form.
   *
   * @return array
   *   Renders the layout builder element, if it exists, and adds it to the
   *   form.
   *
   * @see ::addRenderedLayoutBuilder()
   */
  #[TrustedCallback]
  public static function renderLayoutBuilderAfterForm(array $form): array {
    if (isset($form['#layout_builder_element_keys'])) {
      $layout_builder_element = &NestedArray::getValue($form, $form['#layout_builder_element_keys']);
      // Save the rendered layout builder HTML to a non-rendering child key.
      // Since this method is a pre_render callback, it is assumed that it is
      // called while rendering with an active render context, so that the
      // cache metadata and attachments bubble correctly.
      $form['#layout_builder_markup'] = \Drupal::service('renderer')->render($layout_builder_element);
      // Remove the layout builder child element within form array.
      $layout_builder_element = [];
    }
    return $form;
  }

  /**
   * Render API #post_render callback that adds layout builder markup to form.
   *
   * @param string $html
   *   The rendered form.
   * @param array $form
   *   The form render array.
   *
   * @return string
   *   The render string with any layout builder markup added.
   */
  #[TrustedCallback]
  public static function addRenderedLayoutBuilder(string $html, array $form): string {
    if (isset($form['#layout_builder_markup'])) {
      $html .= $form['#layout_builder_markup'];
    }

    return $html;
  }

  /**
   * Pre-render callback: Renders the Layout Builder UI.
   */
  public function preRender($element) {
    if ($element['#section_storage'] instanceof SectionStorageInterface) {
      $element['layout_builder'] = $this->layout($element['#section_storage']);
    }
    return $element;
  }

  /**
   * Renders the Layout UI.
   *
   * @param \Drupal\layout_builder\SectionStorageInterface $section_storage
   *   The section storage.
   *
   * @return array
   *   A render array.
   */
  protected function layout(SectionStorageInterface $section_storage) {
    $this->prepareLayout($section_storage);

    $output = [];
    if ($this->isAjax()) {
      $output['status_messages'] = [
        '#type' => 'status_messages',
      ];
    }
    $count = 0;
    for ($i = 0; $i < $section_storage->count(); $i++) {
      $output[] = $this->buildAddSectionLink($section_storage, $count);
      $output[] = $this->buildAdministrativeSection($section_storage, $count);
      $count++;
    }
    $output[] = $this->buildAddSectionLink($section_storage, $count);
    $output['#attached']['library'][] = 'layout_builder/drupal.layout_builder';
    // As the Layout Builder UI is typically displayed using the frontend theme,
    // it is not marked as an administrative page at the route level even though
    // it performs an administrative task. Mark this as an administrative page
    // for JavaScript.
    $output['#attached']['drupalSettings']['path']['currentPathIsAdmin'] = TRUE;
    $output['#type'] = 'container';
    $output['#attributes']['id'] = 'layout-builder';
    $output['#attributes']['class'][] = 'layout-builder';
    $output['#attributes']['class'][] = Html::getClass('layout-builder--' . $section_storage->getPluginId());
    // Mark this UI as uncacheable.
    $output['#cache']['max-age'] = 0;
    return $output;
  }

  /**
   * Prepares a layout for use in the UI.
   *
   * @param \Drupal\layout_builder\SectionStorageInterface $section_storage
   *   The section storage.
   */
  protected function prepareLayout(SectionStorageInterface $section_storage) {
    $event = new PrepareLayoutEvent($section_storage);
    $this->eventDispatcher->dispatch($event, LayoutBuilderEvents::PREPARE_LAYOUT);
  }

  /**
   * Builds a link to add a new section at a given delta.
   *
   * @param \Drupal\layout_builder\SectionStorageInterface $section_storage
   *   The section storage.
   * @param int $delta
   *   The delta of the section to splice.
   *
   * @return array
   *   A render array for a link.
   */
  protected function buildAddSectionLink(SectionStorageInterface $section_storage, $delta) {
    $storage_type = $section_storage->getStorageType();
    $storage_id = $section_storage->getStorageId();

    // If the delta and the count are the same, it is either the end of the
    // layout or an empty layout.
    if ($delta === count($section_storage)) {
      if ($delta === 0) {
        $title = $this->t('Add section');
      }
      else {
        $title = $this->t('Add section <span class="visually-hidden">at end of layout</span>');
      }
    }
    // If the delta and the count are different, it is either the beginning of
    // the layout or in between two sections.
    else {
      if ($delta === 0) {
        $title = $this->t('Add section <span class="visually-hidden">at start of layout</span>');
      }
      else {
        $title = $this->t('Add section <span class="visually-hidden">between @first and @second</span>', ['@first' => $delta, '@second' => $delta + 1]);
      }
    }

    return [
      'link' => [
        '#type' => 'link',
        '#title' => $title,
        '#url' => Url::fromRoute('layout_builder.choose_section',
          [
            'section_storage_type' => $storage_type,
            'section_storage' => $storage_id,
            'delta' => $delta,
          ],
          [
            'attributes' => [
              'class' => [
                'use-ajax',
                'layout-builder__link',
                'layout-builder__link--add',
              ],
              'data-dialog-type' => 'dialog',
              'data-dialog-renderer' => 'off_canvas',
            ],
          ]
        ),
      ],
      '#type' => 'container',
      '#attributes' => [
        'class' => ['layout-builder__add-section'],
        'data-layout-builder-highlight-id' => $this->sectionAddHighlightId($delta),
      ],
    ];
  }

  /**
   * Builds the render array for the layout section while editing.
   *
   * @param \Drupal\layout_builder\SectionStorageInterface $section_storage
   *   The section storage.
   * @param int $delta
   *   The delta of the section.
   *
   * @return array
   *   The render array for a given section.
   */
  protected function buildAdministrativeSection(SectionStorageInterface $section_storage, $delta) {
    $storage_type = $section_storage->getStorageType();
    $storage_id = $section_storage->getStorageId();
    $section = $section_storage->getSection($delta);

    $layout = $section->getLayout($this->getPopulatedContexts($section_storage));
    $layout_settings = $section->getLayoutSettings();
    $section_label = !empty($layout_settings['label']) ? $layout_settings['label'] : $this->t('Section @section', ['@section' => $delta + 1]);

    $build = $section->toRenderArray($this->getPopulatedContexts($section_storage), TRUE);
    $layout_definition = $layout->getPluginDefinition();

    $region_labels = $layout_definition->getRegionLabels();
    foreach ($layout_definition->getRegions() as $region => $info) {
      if (!empty($build[$region])) {
        foreach (Element::children($build[$region]) as $uuid) {
          $build[$region][$uuid]['#attributes']['class'][] = 'js-layout-builder-block';
          $build[$region][$uuid]['#attributes']['class'][] = 'layout-builder-block';
          $build[$region][$uuid]['#attributes']['data-layout-block-uuid'] = $uuid;
          $build[$region][$uuid]['#attributes']['data-layout-builder-highlight-id'] = $this->blockUpdateHighlightId($uuid);
          $build[$region][$uuid]['#contextual_links'] = [
            'layout_builder_block' => [
              'route_parameters' => [
                'section_storage_type' => $storage_type,
                'section_storage' => $storage_id,
                'delta' => $delta,
                'region' => $region,
                'uuid' => $uuid,
              ],
              // Add metadata about the current operations available in
              // contextual links. This will invalidate the client-side cache of
              // links that were cached before the 'move' link was added.
              // @see layout_builder.links.contextual.yml
              'metadata' => [
                'operations' => 'move:update:remove',
              ],
            ],
          ];
        }
      }

      $build[$region]['layout_builder_add_block']['link'] = [
        '#type' => 'link',
        // Add one to the current delta since it is zero-indexed.
        '#title' => $this->t('Add block <span class="visually-hidden">in @section, @region region</span>', ['@section' => $section_label, '@region' => $region_labels[$region]]),
        '#url' => Url::fromRoute('layout_builder.choose_block',
          [
            'section_storage_type' => $storage_type,
            'section_storage' => $storage_id,
            'delta' => $delta,
            'region' => $region,
          ],
          [
            'attributes' => [
              'class' => [
                'use-ajax',
                'layout-builder__link',
                'layout-builder__link--add',
              ],
              'data-dialog-type' => 'dialog',
              'data-dialog-renderer' => 'off_canvas',
            ],
          ]
        ),
      ];
      $build[$region]['layout_builder_add_block']['#type'] = 'container';
      $build[$region]['layout_builder_add_block']['#attributes'] = [
        'class' => ['layout-builder__add-block'],
        'data-layout-builder-highlight-id' => $this->blockAddHighlightId($delta, $region),
      ];
      $build[$region]['layout_builder_add_block']['#weight'] = 1000;
      $build[$region]['#attributes']['data-region'] = $region;
      $build[$region]['#attributes']['class'][] = 'layout-builder__region';
      $build[$region]['#attributes']['class'][] = 'js-layout-builder-region';
      $build[$region]['#attributes']['role'] = 'group';
      $build[$region]['#attributes']['aria-label'] = $this->t('@region region in @section', [
        '@region' => $info['label'],
        '@section' => $section_label,
      ]);

      // Get weights of all children for use by the region label.
      $weights = array_map(function ($a) {
        return $a['#weight'] ?? 0;
      }, $build[$region]);

      // The region label is made visible when the move block dialog is open.
      $build[$region]['region_label'] = [
        '#type' => 'container',
        '#attributes' => [
          'class' => ['layout__region-info', 'layout-builder__region-label'],
          // A more detailed version of this information is already read by
          // screen readers, so this label can be hidden from them.
          'aria-hidden' => TRUE,
        ],
        '#markup' => $this->t('Region: @region', ['@region' => $info['label']]),
        // Ensures the region label is displayed first.
        '#weight' => min($weights) - 1,
      ];
    }

    $build['#attributes']['data-layout-update-url'] = Url::fromRoute('layout_builder.move_block', [
      'section_storage_type' => $storage_type,
      'section_storage' => $storage_id,
    ])->toString();

    $build['#attributes']['data-layout-delta'] = $delta;
    $build['#attributes']['class'][] = 'layout-builder__layout';
    $build['#attributes']['data-layout-builder-highlight-id'] = $this->sectionUpdateHighlightId($delta);

    return [
      '#type' => 'container',
      '#attributes' => [
        'class' => ['layout-builder__section'],
        'role' => 'group',
        'aria-label' => $section_label,
      ],
      'remove' => [
        '#type' => 'link',
        '#title' => $this->t('Remove @section', ['@section' => $section_label]),
        '#url' => Url::fromRoute('layout_builder.remove_section', [
          'section_storage_type' => $storage_type,
          'section_storage' => $storage_id,
          'delta' => $delta,
        ]),
        '#attributes' => [
          'class' => [
            'use-ajax',
            'layout-builder__link',
            'layout-builder__link--remove',
          ],
          'data-dialog-type' => 'dialog',
          'data-dialog-renderer' => 'off_canvas',
        ],
      ],
      // The section label is added to sections without a "Configure section"
      // link, and is only visible when the move block dialog is open.
      'section_label' => [
        '#markup' => $this->t('<span class="layout-builder__section-label" aria-hidden="true">@section</span>', ['@section' => $section_label]),
        '#access' => !$layout instanceof PluginFormInterface,
      ],
      'configure' => [
        '#type' => 'link',
        '#title' => $this->t('Configure @section', ['@section' => $section_label]),
        '#access' => $layout instanceof PluginFormInterface,
        '#url' => Url::fromRoute('layout_builder.configure_section', [
          'section_storage_type' => $storage_type,
          'section_storage' => $storage_id,
          'delta' => $delta,
        ]),
        '#attributes' => [
          'class' => [
            'use-ajax',
            'layout-builder__link',
            'layout-builder__link--configure',
          ],
          'data-dialog-type' => 'dialog',
          'data-dialog-renderer' => 'off_canvas',
        ],
      ],
      'layout-builder__section' => $build,
    ];
  }

}