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   1  <?php
   2  /**
   3   * Server-side rendering of the `core/footnotes` block.
   4   *
   5   * @package WordPress
   6   */
   7  
   8  /**
   9   * Renders the `core/footnotes` block on the server.
  10   *
  11   * @since 6.3.0
  12   *
  13   * @param array    $attributes Block attributes.
  14   * @param string   $content    Block default content.
  15   * @param WP_Block $block      Block instance.
  16   *
  17   * @return string Returns the HTML representing the footnotes.
  18   */
  19  function render_block_core_footnotes( $attributes, $content, $block ) {
  20      // Bail out early if the post ID is not set for some reason.
  21      if ( empty( $block->context['postId'] ) ) {
  22          return '';
  23      }
  24  
  25      if ( post_password_required( $block->context['postId'] ) ) {
  26          return;
  27      }
  28  
  29      $footnotes = get_post_meta( $block->context['postId'], 'footnotes', true );
  30  
  31      if ( ! $footnotes ) {
  32          return;
  33      }
  34  
  35      $footnotes = json_decode( $footnotes, true );
  36  
  37      if ( ! is_array( $footnotes ) || count( $footnotes ) === 0 ) {
  38          return '';
  39      }
  40  
  41      $wrapper_attributes = get_block_wrapper_attributes();
  42      $footnote_index     = 1;
  43  
  44      $block_content = '';
  45  
  46      foreach ( $footnotes as $footnote ) {
  47          // Translators: %d: Integer representing the number of return links on the page.
  48          $aria_label     = sprintf( __( 'Jump to footnote reference %1$d' ), $footnote_index );
  49          $block_content .= sprintf(
  50              '<li id="%1$s">%2$s <a href="#%1$s-link" aria-label="%3$s">↩︎</a></li>',
  51              $footnote['id'],
  52              $footnote['content'],
  53              $aria_label
  54          );
  55          ++$footnote_index;
  56      }
  57  
  58      return sprintf(
  59          '<ol %1$s>%2$s</ol>',
  60          $wrapper_attributes,
  61          $block_content
  62      );
  63  }
  64  
  65  /**
  66   * Registers the `core/footnotes` block on the server.
  67   *
  68   * @since 6.3.0
  69   */
  70  function register_block_core_footnotes() {
  71      register_block_type_from_metadata(
  72          __DIR__ . '/footnotes',
  73          array(
  74              'render_callback' => 'render_block_core_footnotes',
  75          )
  76      );
  77  }
  78  add_action( 'init', 'register_block_core_footnotes' );
  79  
  80  
  81  /**
  82   * Registers the footnotes meta field required for footnotes to work.
  83   *
  84   * @since 6.5.0
  85   */
  86  function register_block_core_footnotes_post_meta() {
  87      $post_types = get_post_types( array( 'show_in_rest' => true ) );
  88      foreach ( $post_types as $post_type ) {
  89          // Only register the meta field if the post type supports the editor, custom fields, and revisions.
  90          if (
  91              post_type_supports( $post_type, 'editor' ) &&
  92              post_type_supports( $post_type, 'custom-fields' ) &&
  93              post_type_supports( $post_type, 'revisions' )
  94          ) {
  95              register_post_meta(
  96                  $post_type,
  97                  'footnotes',
  98                  array(
  99                      'show_in_rest'      => true,
 100                      'single'            => true,
 101                      'type'              => 'string',
 102                      'revisions_enabled' => true,
 103                  )
 104              );
 105          }
 106      }
 107  }
 108  /*
 109   * Most post types are registered at priority 10, so use priority 20 here in
 110   * order to catch them.
 111  */
 112  add_action( 'init', 'register_block_core_footnotes_post_meta', 20 );
 113  
 114  /**
 115   * Adds the footnotes field to the revisions display.
 116   *
 117   * @since 6.3.0
 118   *
 119   * @param array $fields The revision fields.
 120   * @return array The revision fields.
 121   */
 122  function wp_add_footnotes_to_revision( $fields ) {
 123      $fields['footnotes'] = __( 'Footnotes' );
 124      return $fields;
 125  }
 126  add_filter( '_wp_post_revision_fields', 'wp_add_footnotes_to_revision' );
 127  
 128  /**
 129   * Gets the footnotes field from the revision for the revisions screen.
 130   *
 131   * @since 6.3.0
 132   *
 133   * @param string $revision_field The field value, but $revision->$field
 134   *                               (footnotes) does not exist.
 135   * @param string $field          The field name, in this case "footnotes".
 136   * @param object $revision       The revision object to compare against.
 137   * @return string The field value.
 138   */
 139  function wp_get_footnotes_from_revision( $revision_field, $field, $revision ) {
 140      return get_metadata( 'post', $revision->ID, $field, true );
 141  }
 142  add_filter( '_wp_post_revision_field_footnotes', 'wp_get_footnotes_from_revision', 10, 3 );