Add auto heading id filter to the wysiwyg format on install.

composer.json

@@ -12,7 +12,6 @@
         }
     ],
     "require": {
-        "drupal/auto_heading_ids": "^2.0@beta",
         "localgovdrupal/localgov_core": ">=2.1.10",
         "localgovdrupal/localgov_paragraphs": ">=2.4.0"
     },

localgov_publications.info.yml

@@ -5,7 +5,6 @@ package: LocalGov Drupal
 core_version_requirement: ^9 || ^10
 
 dependencies:
-  - auto_heading_ids:auto_heading_ids
   - drupal:book
   - drupal:menu_ui
   - drupal:views

localgov_publications.install

@@ -5,17 +5,40 @@
  * Install, update and uninstall functions for the LocalGov Publications module.
  */
 
+use Drupal\filter\Entity\FilterFormat;
+use Drupal\filter\FilterFormatInterface;
+
 /**
  * Implements hook_install().
  */
 function localgov_publications_install() {
+
+  // Add our localgov_publication_page content type to
+  // book.settings.allowed_types. This lets editors create publication pages.
   $config = \Drupal::configFactory()->getEditable('book.settings');
   $allowed_types = $config->get('allowed_types');
   $allowed_types[] = 'localgov_publication_page';
   $config->set('allowed_types', $allowed_types);
   $config->save();
+
+  // Add our localgov-publication-cover-page-alias to
+  // pathauto.settings.safe_tokens. This prevents double escaping in the
+  // resulting URL.
   $path_auto_config = \Drupal::configFactory()->getEditable('pathauto.settings');
   $safe_tokens = $path_auto_config->get('safe_tokens');
   $safe_tokens[] = 'localgov-publication-cover-page-alias';
   $path_auto_config->set('safe_tokens', $safe_tokens)->save();
+
+  // Add heading_id_filter from the auto_heading_ids module to the wysiwyg
+  // filter format. This is required for the ToC block to work consistently.
+  $wysiwygFormat = FilterFormat::load('wysiwyg');
+  if ($wysiwygFormat instanceof FilterFormatInterface) {
+    $wysiwygFormat->setFilterConfig('localgov_publications_heading_ids', [
+      'status' => TRUE,
+      'settings' => [
+        'keep_existing_ids' => TRUE,
+      ],
+    ]);
+    $wysiwygFormat->save();
+  }
 }

src/Plugin/Filter/HeadingIdFilter.php

@@ -0,0 +1,158 @@
+<?php
+
+namespace Drupal\localgov_publications\Plugin\Filter;
+
+use Drupal\Component\Utility\Html;
+use Drupal\Component\Utility\Unicode;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\Transliteration\PhpTransliteration;
+use Drupal\filter\FilterProcessResult;
+use Drupal\filter\Plugin\FilterBase;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Apply identifiers (anchors) to headings in content.
+ *
+ * This filter is copied from the auto_heading_ids module.
+ *
+ * @Filter(
+ *   id = "localgov_publications_heading_ids",
+ *   title = @Translation("Automatically apply identifiers (anchors) to headings in content"),
+ *   type = Drupal\filter\Plugin\FilterInterface::TYPE_TRANSFORM_IRREVERSIBLE,
+ *   weight = 10
+ * )
+ */
+class HeadingIdFilter extends FilterBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * Word separator.
+   */
+  const SEPARATOR = '-';
+
+  /**
+   * Transliteration service.
+   *
+   * @var \Drupal\Core\Transliteration\PhpTransliteration
+   */
+  protected $transliteration;
+
+  /**
+   * Constructs a \Drupal\editor\Plugin\Filter\EditorFileReference object.
+   *
+   * @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 \Drupal\Core\Transliteration\PhpTransliteration $transliteration
+   *   The transliteration service instance.
+   *
+   * @internal param \Drupal\Core\Entity\EntityManagerInterface $entity_manager An entity manager object.*   An entity manager object.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, PhpTransliteration $transliteration) {
+    $this->transliteration = $transliteration;
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $container->get('transliteration')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function process($text, $langcode) {
+    return new FilterProcessResult($this->filterAttributes($text));
+  }
+
+  /**
+   * Applies ids to headings.
+   *
+   * @param string $text
+   *   The HTML text string to be filtered.
+   *
+   * @return string
+   *   Filtered HTML.
+   */
+  public function filterAttributes($text) {
+    $output = $text;
+    $html_dom = Html::load($text);
+    $xpath = new \DOMXPath($html_dom);
+    $heading_tags = '//h2|//h3|//h4|//h5|//h6';
+    $keep_existing_ids = $this->settings['keep_existing_ids'] ?? FALSE;
+
+    // Apply attribute restrictions to headings.
+    $headings_found = FALSE;
+    foreach ($xpath->query($heading_tags) as $heading_tag) {
+
+      if ($keep_existing_ids && $heading_tag->hasAttribute('id')) {
+        continue;
+      }
+
+      $id = $this->transformHeadingToId($heading_tag->nodeValue);
+      $heading_tag->setAttribute('id', Html::getUniqueId($id));
+      $headings_found = TRUE;
+    }
+
+    if ($headings_found) {
+      // Only bother serializing if something changed.
+      $output = Html::serialize($html_dom);
+      $output = trim($output);
+    }
+
+    return $output;
+  }
+
+  /**
+   * Creates a machine name based on the heading.
+   *
+   * Inspired by Drupal\migrate\Plugin\migrate\process\MachineName::transform.
+   * Improved by Drupal\pathauto\AliasCleaner.
+   *
+   * @param string $heading
+   *   String to convert to id.
+   *
+   * @return mixed
+   *   A dash separated id.
+   */
+  public function transformHeadingToId($heading) {
+    // Reduce to ascii.
+    $new_value = $this->transliteration->transliterate($heading);
+    // Reduce to letters and numbers.
+    $new_value = preg_replace('/[^a-zA-Z0-9\/]+/', static::SEPARATOR, $new_value);
+    // Remove consecutive separators.
+    $new_value = preg_replace('/' . static::SEPARATOR . '+/', static::SEPARATOR, $new_value);
+    // Remove leading and trailing separators.
+    $new_value = trim($new_value, static::SEPARATOR);
+    // Convert to lowercase.
+    $new_value = mb_strtolower($new_value);
+    // Truncate to 128 chars.
+    return Unicode::truncate($new_value, 128, TRUE);
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  public function settingsForm(array $form, FormStateInterface $form_state) {
+
+    $form['keep_existing_ids'] = [
+      '#title' => 'Keep existing IDs',
+      '#type' => 'checkbox',
+      '#default_value' => $this->settings['keep_existing_ids'] ?? FALSE,
+      '#description' => $this->t('When this is selected, existing IDs in content will not be changed.'),
+    ];
+
+    return $form;
+  }
+
+}