1 files changed, 120 insertions, 0 deletions
diff --git a/wp-includes/blocks/footnotes.php b/wp-includes/blocks/footnotes.php
new file mode 100644
index 0000000..bc6291d
--- /dev/null
+++ b/wp-includes/blocks/footnotes.php
@@ -0,0 +1,120 @@
+<?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() {
+	foreach ( array( 'post', 'page' ) as $post_type ) {
+		register_post_meta(
+			$post_type,
+			'footnotes',
+			array(
+				'show_in_rest'      => true,
+				'single'            => true,
+				'type'              => 'string',
+				'revisions_enabled' => true,
+			)
+		);
+	}
+	register_block_type_from_metadata(
+		__DIR__ . '/footnotes',
+		array(
+			'render_callback' => 'render_block_core_footnotes',
+		)
+	);
+}
+add_action( 'init', 'register_block_core_footnotes' );
+
+/**
+ * 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 );