<?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 );