<?php
/**
* Server-side rendering of the `core/footnotes` block.
*
* @package WordPress
*/

/**
* Renders the `core/footnotes` block on the server.
*
* @since 6.3.0
*
* @param array $attributes Block attributes.
* @param string $content Block default content.
* @param WP_Block $block Block instance.
*
* @return string Returns the HTML representing the footnotes.
*/
function render_block_core_footnotes( $attributes, $content, $block ) {
// Bail out early if the post ID is not set for some reason.
if ( empty( $block->context['postId'] ) ) {
return '';
}

if ( post_password_required( $block->context['postId'] ) ) {
return;
}

$footnotes = get_post_meta( $block->context['postId'], 'footnotes', true );

if ( ! $footnotes ) {
return;
}

$footnotes = json_decode( $footnotes, true );

if ( ! is_array( $footnotes ) || count( $footnotes ) === 0 ) {
return '';
}

$wrapper_attributes = get_block_wrapper_attributes();
$footnote_index = 1;

$block_content = '';

foreach ( $footnotes as $footnote ) {
// Translators: %d: Integer representing the number of return links on the page.
$aria_label = sprintf( __( 'Jump to footnote reference %1$d' ), $footnote_index );
$block_content .= sprintf(
'<li id="%1$s">%2$s <a href="#%1$s-link" aria-label="%3$s">↩︎</a></li>',
$footnote['id'],
$footnote['content'],
$aria_label
);
++$footnote_index;
}

return sprintf(
'<ol %1$s>%2$s</ol>',
$wrapper_attributes,
$block_content
);
}

/**
* Registers the `core/footnotes` block on the server.
*
* @since 6.3.0
*/
function register_block_core_footnotes() {
register_block_type_from_metadata(
__DIR__ . '/footnotes',
array(
'render_callback' => 'render_block_core_footnotes',
)
);
}
add_action( 'init', 'register_block_core_footnotes' );


/**
* Registers the footnotes meta field required for footnotes to work.
*
* @since 6.5.0
*/
function register_block_core_footnotes_post_meta() {
$post_types = get_post_types( array( 'show_in_rest' => true ) );
foreach ( $post_types as $post_type ) {
// Only register the meta field if the post type supports the editor, custom fields, and revisions.
if (
post_type_supports( $post_type, 'editor' ) &&
post_type_supports( $post_type, 'custom-fields' ) &&
post_type_supports( $post_type, 'revisions' )
) {
register_post_meta(
$post_type,
'footnotes',
array(
'show_in_rest' => true,
'single' => true,
'type' => 'string',
'revisions_enabled' => true,
)
);
}
}
}
/*
* Most post types are registered at priority 10, so use priority 20 here in
* order to catch them.
*/
add_action( 'init', 'register_block_core_footnotes_post_meta', 20 );

/**
* Adds the footnotes field to the revisions display.
*
* @since 6.3.0
*
* @param array $fields The revision fields.
* @return array The revision fields.
*/
function wp_add_footnotes_to_revision( $fields ) {
$fields['footnotes'] = __( 'Footnotes' );
return $fields;
}
add_filter( '_wp_post_revision_fields', 'wp_add_footnotes_to_revision' );

/**
* Gets the footnotes field from the revision for the revisions screen.
*
* @since 6.3.0
*
* @param string $revision_field The field value, but $revision->$field
* (footnotes) does not exist.
* @param string $field The field name, in this case "footnotes".
* @param object $revision The revision object to compare against.
* @return string The field value.
*/
function wp_get_footnotes_from_revision( $revision_field, $field, $revision ) {
return get_metadata( 'post', $revision->ID, $field, true );
}
add_filter( '_wp_post_revision_field_footnotes', 'wp_get_footnotes_from_revision', 10, 3 );