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 */
 19function 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 */
 70function 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}
 78add_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 */
 86function 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*/
112add_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 */
122function wp_add_footnotes_to_revision( $fields ) {
123	$fields['footnotes'] = __( 'Footnotes' );
124	return $fields;
125}
126add_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 */
139function wp_get_footnotes_from_revision( $revision_field, $field, $revision ) {
140	return get_metadata( 'post', $revision->ID, $field, true );
141}
142add_filter( '_wp_post_revision_field_footnotes', 'wp_get_footnotes_from_revision', 10, 3 );
143