Footnotes: store in revisions

packages/block-library/src/footnotes/index.php

@@ -78,3 +78,129 @@ function register_block_core_footnotes() {
 	);
 }
 add_action( 'init', 'register_block_core_footnotes' );
+
+add_action(
+	'wp_after_insert_post',
+	/**
+	 * Saves the footnotes meta value to the revision.
+	 *
+	 * @param int $revision_id The revision ID.
+	 */
+	function( $revision_id ) {
+		$post_id = wp_is_post_revision( $revision_id );
+
+		if ( $post_id ) {
+			$footnotes = get_post_meta( $post_id, 'footnotes', true );
+
+			if ( $footnotes ) {
+				// Can't use update_post_meta() because it doesn't allow revisions.
+				update_metadata( 'post', $revision_id, 'footnotes', $footnotes );
+			}
+		}
+	}
+);
+
+add_action(
+	'_wp_put_post_revision',
+	/**
+	 * Keeps track of the revision ID for "rest_after_insert_{$post_type}".
+	 *
+	 * @param int $revision_id The revision ID.
+	 */
+	function( $revision_id ) {
+		global $_gutenberg_revision_id;
+		$_gutenberg_revision_id = $revision_id;
+	}
+);
+
+foreach ( array( 'post', 'page' ) as $post_type ) {
+	add_action(
+		"rest_after_insert_{$post_type}",
+		/**
+		 * This is a specific fix for the REST API. The REST API doesn't update
+		 * the post and post meta in one go (through `meta_input`). While it
+		 * does fix the `wp_after_insert_post` hook to be called correctly after
+		 * updating meta, it does NOT fix hooks such as post_updated and
+		 * save_post, which are normally also fired after post meta is updated
+		 * in `wp_insert_post()`. Unfortunately, `wp_save_post_revision` is
+		 * added to the `post_updated` action, which means the meta is not
+		 * available at the time, so we have to add it afterwards through the
+		 * `"rest_after_insert_{$post_type}"` action.
+		 *
+		 * @param WP_Post $post The post object.
+		 */
+		function( $post ) {
+			global $_gutenberg_revision_id;
+
+			if ( $_gutenberg_revision_id ) {
+				$revision = get_post( $_gutenberg_revision_id );
+				$post_id  = $revision->post_parent;
+
+				// Just making sure we're updating the right revision.
+				if ( $post->ID === $post_id ) {
+					$footnotes = get_post_meta( $post_id, 'footnotes', true );
+
+					if ( $footnotes ) {
+						// Can't use update_post_meta() because it doesn't allow revisions.
+						update_metadata( 'post', $_gutenberg_revision_id, 'footnotes', $footnotes );
+					}
+				}
+			}
+		}
+	);
+}
+
+add_action(
+	'wp_restore_post_revision',
+	/**
+	 * Restores the footnotes meta value from the revision.
+	 *
+	 * @param int $post_id      The post ID.
+	 * @param int $revision_id  The revision ID.
+	 */
+	function( $post_id, $revision_id ) {
+		$footnotes = get_post_meta( $revision_id, 'footnotes', true );
+
+		if ( $footnotes ) {
+			update_post_meta( $post_id, 'footnotes', $footnotes );
+		} else {
+			delete_post_meta( $post_id, 'footnotes' );
+		}
+	},
+	10,
+	2
+);
+
+add_filter(
+	'_wp_post_revision_fields',
+	/**
+	 * Adds the footnotes field to the revision.
+	 *
+	 * @param array $fields The revision fields.
+	 *
+	 * @return array The revision fields.
+	 */
+	function( $fields ) {
+		$fields['footnotes'] = __( 'Footnotes' );
+		return $fields;
+	}
+);
+
+add_filter(
+	'wp_post_revision_field_footnotes',
+	/**
+	 * Gets the footnotes field from the revision.
+	 *
+	 * @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( $revision_field, $field, $revision ) {
+		return get_metadata( 'post', $revision->ID, $field, true );
+	},
+	10,
+	3
+);

test/e2e/specs/editor/various/footnotes.spec.js

@@ -3,9 +3,11 @@
  */
 const { test, expect } = require( '@wordpress/e2e-test-utils-playwright' );
 
-async function getFootnotes( page ) {
+async function getFootnotes( page, withoutSave = false ) {
 	// Save post so we can check meta.
-	await page.click( 'button:text("Save draft")' );
+	if ( ! withoutSave ) {
+		await page.click( 'button:text("Save draft")' );
+	}
 	await page.waitForSelector( 'button:text("Saved")' );
 	const footnotes = await page.evaluate( () => {
 		return window.wp.data
@@ -278,4 +280,84 @@ test.describe( 'Footnotes', () => {
 			},
 		] );
 	} );
+
+	test( 'works with revisions', async ( { editor, page } ) => {
+		await editor.canvas.click( 'role=button[name="Add default block"i]' );
+		await page.keyboard.type( 'first paragraph' );
+		await page.keyboard.press( 'Enter' );
+		await page.keyboard.type( 'second paragraph' );
+
+		await editor.showBlockToolbar();
+		await editor.clickBlockToolbarButton( 'More' );
+		await page.locator( 'button:text("Footnote")' ).click();
+
+		await page.keyboard.type( 'first footnote' );
+
+		const id1 = await editor.canvas.evaluate( () => {
+			return document.activeElement.id;
+		} );
+
+		await editor.canvas.click( 'p:text("first paragraph")' );
+
+		await editor.showBlockToolbar();
+		await editor.clickBlockToolbarButton( 'More' );
+		await page.locator( 'button:text("Footnote")' ).click();
+
+		await page.keyboard.type( 'second footnote' );
+
+		const id2 = await editor.canvas.evaluate( () => {
+			return document.activeElement.id;
+		} );
+
+		// This also saves the post!
+		expect( await getFootnotes( page ) ).toMatchObject( [
+			{
+				content: 'second footnote',
+				id: id2,
+			},
+			{
+				content: 'first footnote',
+				id: id1,
+			},
+		] );
+
+		await editor.canvas.click( 'p:text("first paragraph")' );
+
+		await editor.showBlockToolbar();
+		await editor.clickBlockToolbarButton( 'Move down' );
+
+		// This also saves the post!
+		expect( await getFootnotes( page ) ).toMatchObject( [
+			{
+				content: 'first footnote',
+				id: id1,
+			},
+			{
+				content: 'second footnote',
+				id: id2,
+			},
+		] );
+
+		// Open revisions.
+		await editor.openDocumentSettingsSidebar();
+		await page
+			.getByRole( 'region', { name: 'Editor settings' } )
+			.getByRole( 'button', { name: 'Post' } )
+			.click();
+		await page.locator( 'a:text("2 Revisions")' ).click();
+		await page.locator( '.revisions-controls .ui-slider-handle' ).focus();
+		await page.keyboard.press( 'ArrowLeft' );
+		await page.locator( 'input:text("Restore This Revision")' ).click();
+
+		expect( await getFootnotes( page, true ) ).toMatchObject( [
+			{
+				content: 'second footnote',
+				id: id2,
+			},
+			{
+				content: 'first footnote',
+				id: id1,
+			},
+		] );
+	} );
 } );