video_embed_field-8.x-2.4/modules/video_embed_wysiwyg/video_embed_wysiwyg.module

<?php

/**
 * @file
 * Module file for video_embed_wysiwyg.
 */

use Drupal\Core\Form\FormStateInterface;
use Drupal\video_embed_wysiwyg\VideoEmbedWysiwygConstants;
use Drupal\Component\Utility\UrlHelper;

/**
 * Implements hook_form_FORM_ID_alter().
 */
function video_embed_wysiwyg_form_filter_format_form_alter(&$form, $form_state, $form_id) {
  $form['#validate'][] = 'video_embed_wysiwyg_filter_weight_validate';
}

/**
 * Validate the filters are not in an order that will cause conflicts.
 */
function video_embed_wysiwyg_filter_weight_validate($form, FormStateInterface $form_state) {
  // Don't validate if the WYSIWYG filter is not enabled.
  if (empty($form_state->getValue(['filters', 'video_embed_wysiwyg', 'status']))) {
    return;
  }

  $wysiwyg_weight = $form_state->getValue(['filters', 'video_embed_wysiwyg', 'weight']);

  // Check the WYSIWYG filter runs before url filtering.
  if (!empty($form_state->getValue(['filters', 'filter_url', 'status']))) {
    $filter_weight = $form_state->getValue(['filters', 'filter_url', 'weight']);
    if ($wysiwyg_weight > $filter_weight) {
      $form_state->setError($form['filters']['status']['video_embed_wysiwyg'], t('The "Video Embed WYSIWYG" filter must run before the "Convert URLs into links" filter to function correctly. For more information <a href="@url">read the documentation</a>.', ['@url' => VideoEmbedWysiwygConstants::VIDEO_EMBED_WYSIWYG_DOCUMENTATION_URL]));
    }
  }
  // Check the WYSIWYG filter runs after the HTML tag filter.
  if (!empty($form_state->getValue(['filters', 'filter_html', 'status']))) {
    $html_filter_weight = $form_state->getValue(['filters', 'filter_html', 'weight']);
    if ($wysiwyg_weight < $html_filter_weight) {
      $form_state->setError($form['filters']['status']['video_embed_wysiwyg'], t('The "Video Embed WYSIWYG" filter must run after the "Limit allowed HTML tags" filter to function correctly. For more information <a href="@url">read the documentation</a>.', ['@url' => VideoEmbedWysiwygConstants::VIDEO_EMBED_WYSIWYG_DOCUMENTATION_URL]));
    }
  }
}

/**
 * Directly taken from https://www.drupal.org/docs/core-modules-and-themes/core-modules/ckeditor-5-module/how-to-style-custom-content-in-ckeditor-5#s-registering-ckeditor-5-stylesheets-from-a-module.
 *
 * Implements hook_library_info_alter().
 */
function video_embed_wysiwyg_library_info_alter(&$libraries, $extension) {
  $module = 'video_embed_wysiwyg';
  if ($extension === 'ckeditor5') {
    // Add paths to stylesheets specified by a modules's ckeditor5-stylesheets
    // config property.
    $module_path = \Drupal::service('extension.list.module')->getPath($module);
    $info = \Drupal::service('extension.list.module')->getExtensionInfo($module);
    if (isset($info['ckeditor5-stylesheets']) && $info['ckeditor5-stylesheets'] !== FALSE) {
      $css = $info['ckeditor5-stylesheets'];
      foreach ($css as $key => $url) {
        // CSS URL is external or relative to Drupal root.
        if (UrlHelper::isExternal($url) || $url[0] === '/') {
          $css[$key] = $url;
        }
        // CSS URL is relative to theme.
        else {
          $css[$key] = '/' . $module_path . '/' . $url;
        }
      }
    }
    if (!isset($libraries['internal.drupal.ckeditor5.stylesheets']['css']['theme'])) {
      $libraries['internal.drupal.ckeditor5.stylesheets'] = [
        'css' => [
          'theme' => array_fill_keys(array_values($css), []),
        ],
      ];
    }
    else {
      foreach (array_values($css) as $value) {
        $libraries['internal.drupal.ckeditor5.stylesheets']['css']['theme'][$value] = [];
      }
    }
  }
}