Rework PR 4218

editor/components/provider/index.js

@@ -19,7 +19,7 @@ import {
 /**
  * Internal Dependencies
  */
-import { setupEditor, undo, redo, createUndoLevel } from '../../store/actions';
+import { setupEditor, undo, redo, showAutosaveNotice, createUndoLevel } from '../../store/actions';
 import store from '../../store';
 
 class EditorProvider extends Component {
@@ -37,6 +37,11 @@ class EditorProvider extends Component {
 				} )
 			);
 		}
+
+		// Display a notice if an autosave exists.
+		if ( props.settings.autosave ) {
+			this.store.dispatch( showAutosaveNotice( props.settings.autosave ) );
+		}
 	}
 
 	render() {

editor/store/actions.js

@@ -393,6 +393,19 @@ export function autosave() {
 	};
 }
 
+/**
+ * Returns an action to show the autosave notice.
+ *
+ * @param  {boolean} autosaveStatus Autosave status and data including a link to the autosave.
+ * @return {Object}                 Action object
+ */
+export function showAutosaveNotice( autosaveStatus ) {
+	return {
+		type: 'REQUEST_AUTOSAVE_NOTICE',
+		autosaveStatus,
+	};
+}
+
 /**
  * Returns an action object used in signalling that undo history should
  * restore last popped state.

editor/store/effects.js

@@ -34,6 +34,7 @@ import {
 	replaceBlocks,
 	createSuccessNotice,
 	createErrorNotice,
+	createWarningNotice,
 	removeNotice,
 	savePost,
 	saveSharedBlock,
@@ -71,6 +72,7 @@ import {
  * Module Constants
  */
 const SAVE_POST_NOTICE_ID = 'SAVE_POST_NOTICE_ID';
+const AUTOSAVE_POST_NOTICE_ID = 'AUTOSAVE_POST_NOTICE_ID';
 const TRASH_POST_NOTICE_ID = 'TRASH_POST_NOTICE_ID';
 const SHARED_BLOCK_NOTICE_ID = 'SHARED_BLOCK_NOTICE_ID';
 
@@ -109,6 +111,7 @@ export default {
 			optimist: { type: BEGIN, id: POST_UPDATE_TRANSACTION_ID },
 		} );
 		dispatch( removeNotice( SAVE_POST_NOTICE_ID ) );
+		dispatch( removeNotice( AUTOSAVE_POST_NOTICE_ID ) );
 		const basePath = wp.api.getPostTypeRoute( getCurrentPostType( state ) );
 		wp.apiRequest( { path: `/wp/v2/${ basePath }/${ post.id }`, method: 'PUT', data: toSend } ).then(
 			( newPost ) => {
@@ -201,6 +204,24 @@ export default {
 			__( 'Updating failed' );
 		dispatch( createErrorNotice( noticeMessage, { id: SAVE_POST_NOTICE_ID } ) );
 	},
+	REQUEST_AUTOSAVE_NOTICE( action, store ) {
+		const { autosaveStatus } = action;
+		const { dispatch } = store;
+		const noticeMessage = __( 'There is an autosave of this post that is more recent than the version below.' );
+		if ( autosaveStatus ) {
+			dispatch( createWarningNotice(
+				<p>
+					<span>{ noticeMessage }</span>
+					{ ' ' }
+					{ <a href={ autosaveStatus.editLink }>{ __( 'View the autosave' ) }</a> }
+				</p>,
+				{
+					id: AUTOSAVE_POST_NOTICE_ID,
+					spokenMessage: noticeMessage,
+				}
+			) );
+		}
+	},
 	TRASH_POST( action, store ) {
 		const { dispatch, getState } = store;
 		const { postId } = action;

editor/store/reducer.js

@@ -896,6 +896,24 @@ export function notices( state = [], action ) {
 	return state;
 }
 
+/**
+ * Reducer returning the currently autosave message.
+ *
+ * @param  {Object} state  Current state.
+ * @param  {Object} action Dispatched action.
+ *
+ * @return {Object}        Updated state.
+ */
+export function autosave( state = { message: '' }, action ) {
+	switch ( action.type ) {
+		case 'UPDATE_AUTOSAVE_STATUS_MESSAGE':
+			return {
+				...state,
+				message: action.message,
+			};
+	}
+}
+
 export const sharedBlocks = combineReducers( {
 	data( state = {}, action ) {
 		switch ( action.type ) {

lib/client-assets.php

@@ -799,6 +799,41 @@ function gutenberg_capture_code_editor_settings( $settings ) {
 	$gutenberg_captured_code_editor_settings = $settings;
 	return false;
 }
+/**
+ * Retrieve a stored autosave that is newer than the post save.
+ *
+ * Deletes autosaves that are older than the post save.
+ *
+ * @param  WP_Post $post Post object.
+ * @return WP_Post|boolean The post autosave. False if none found.
+ */
+function get_autosave_newer_than_post_save( $post ) {
+	// Add autosave data if it is newer and changed.
+	$autosave      = wp_get_post_autosave( $post->ID );
+	$show_autosave = false;
+
+	// Check if we have an autosave that is newer than the post and different from the current post.
+	if (
+		$autosave &&
+		mysql2date( 'U', $autosave->post_modified_gmt, false ) > mysql2date( 'U', $post->post_modified_gmt, false )
+	) {
+		// Iterate thru revisioned fields checking for any changes.
+		foreach ( _wp_post_revision_fields( $post ) as $autosave_field => $_autosave_field ) {
+			if ( normalize_whitespace( $autosave->$autosave_field ) != normalize_whitespace( $post->$autosave_field ) ) {
+				$show_autosave = true;
+				break;
+			}
+		}
+	}
+
+	// If this autosave isn't newer and different from the current post, remove.
+	if ( $autosave && ! $show_autosave ) {
+		wp_delete_post_revision( $autosave->ID );
+		return false;
+	}
+
+	return $autosave;
+}
 
 /**
  * Scripts & Styles.
@@ -950,6 +985,13 @@ function gutenberg_editor_scripts_and_styles( $hook ) {
 		'bodyPlaceholder'     => apply_filters( 'write_your_story', __( 'Write your story', 'gutenberg' ), $post ),
 	);
 
+	$post_autosave = get_autosave_newer_than_post_save( $post );
+	if ( $post_autosave ) {
+		$editor_settings['autosave'] = array(
+			'editLink' => add_query_arg( 'gutenberg', true, get_edit_post_link( $post_autosave->ID ) ),
+		);
+	}
+
 	if ( ! empty( $color_palette ) ) {
 		$editor_settings['colors'] = $color_palette;
 	}