Add parent navigation support for the navigator component (#47883)

Co-authored-by: Marco Ciampini <marco.ciampo@gmail.com>

docs/manifest.json

@@ -1067,6 +1067,12 @@
 		"markdown_source": "../packages/components/src/navigator/navigator-screen/README.md",
 		"parent": "components"
 	},
+	{
+		"title": "NavigatorToParentButton",
+		"slug": "navigator-to-parent-button",
+		"markdown_source": "../packages/components/src/navigator/navigator-to-parent-button/README.md",
+		"parent": "components"
+	},
 	{
 		"title": "Notice",
 		"slug": "notice",

packages/components/CHANGELOG.md

@@ -10,6 +10,7 @@
 
 -   `ColorPalette`: ensure text label contrast checking works with CSS variables ([#47373](https://github.com/WordPress/gutenberg/pull/47373)).
 -  `Navigator`: Support dynamic paths with parameters ([#47827](https://github.com/WordPress/gutenberg/pull/47827)).
+-  `Navigator`: Support hierarchical paths navigation and add `NavigatorToParentButton` component ([#47883](https://github.com/WordPress/gutenberg/pull/47883)).
 
 ### Internal
 

packages/components/src/index.js

@@ -115,6 +115,7 @@ export {
 	NavigatorScreen as __experimentalNavigatorScreen,
 	NavigatorButton as __experimentalNavigatorButton,
 	NavigatorBackButton as __experimentalNavigatorBackButton,
+	NavigatorToParentButton as __experimentalNavigatorToParentButton,
 	useNavigator as __experimentalUseNavigator,
 } from './navigator';
 export { default as Notice } from './notice';

packages/components/src/navigator/context.ts

@@ -12,6 +12,7 @@ const initialContextValue: NavigatorContextType = {
 	location: {},
 	goTo: () => {},
 	goBack: () => {},
+	goToParent: () => {},
 	addScreen: () => {},
 	removeScreen: () => {},
 	params: {},

packages/components/src/navigator/index.ts

@@ -2,4 +2,5 @@ export { NavigatorProvider } from './navigator-provider';
 export { NavigatorScreen } from './navigator-screen';
 export { NavigatorButton } from './navigator-button';
 export { NavigatorBackButton } from './navigator-back-button';
+export { NavigatorToParentButton } from './navigator-to-parent-button';
 export { default as useNavigator } from './use-navigator';

packages/components/src/navigator/navigator-back-button/README.md

@@ -10,22 +10,6 @@ The `NavigatorBackButton` component can be used to navigate to a screen and shou
 
 Refer to [the `NavigatorProvider` component](/packages/components/src/navigator/navigator-provider/README.md#usage) for a usage example.
 
-## Props
-
-The component accepts the following props:
-
-### `onClick`: `React.MouseEventHandler< HTMLElement >`
-
-The callback called in response to a `click` event.
-
--   Required: No
-
-### `path`: `string`
-
-The path of the screen to navigate to.
-
--   Required: Yes
-
 ### Inherited props
 
-`NavigatorBackButton` also inherits all of the [`Button` props](/packages/components/src/button/README.md#props), except for `href`.
+`NavigatorBackButton` also inherits all of the [`Button` props](/packages/components/src/button/README.md#props), except for `href` and `target`.

packages/components/src/navigator/navigator-back-button/hook.ts

@@ -9,26 +9,31 @@ import { useCallback } from '@wordpress/element';
 import { useContextSystem, WordPressComponentProps } from '../../ui/context';
 import Button from '../../button';
 import useNavigator from '../use-navigator';
-import type { NavigatorBackButtonProps } from '../types';
+import type { NavigatorBackButtonHookProps } from '../types';
 
 export function useNavigatorBackButton(
-	props: WordPressComponentProps< NavigatorBackButtonProps, 'button' >
+	props: WordPressComponentProps< NavigatorBackButtonHookProps, 'button' >
 ) {
 	const {
 		onClick,
 		as = Button,
+		goToParent: goToParentProp = false,
 		...otherProps
 	} = useContextSystem( props, 'NavigatorBackButton' );
 
-	const { goBack } = useNavigator();
+	const { goBack, goToParent } = useNavigator();
 	const handleClick: React.MouseEventHandler< HTMLButtonElement > =
 		useCallback(
 			( e ) => {
 				e.preventDefault();
-				goBack();
+				if ( goToParentProp ) {
+					goToParent();
+				} else {
+					goBack();
+				}
 				onClick?.( e );
 			},
-			[ goBack, onClick ]
+			[ goToParentProp, goToParent, goBack, onClick ]
 		);
 
 	return {

packages/components/src/navigator/navigator-provider/README.md

@@ -4,7 +4,7 @@
 This feature is still experimental. “Experimental” means this is an early implementation subject to drastic and breaking changes.
 </div>
 
-The `NavigatorProvider` component allows rendering nested views/panels/menus (via the [`NavigatorScreen` component](/packages/components/src/navigator/navigator-screen/README.md)) and navigate between these different states (via the [`NavigatorButton`](/packages/components/src/navigator/navigator-button/README.md) and [`NavigatorBackButton`](/packages/components/src/navigator/navigator-back-button/README.md) components or the `useNavigator` hook). The Global Styles sidebar is an example of this.
+The `NavigatorProvider` component allows rendering nested views/panels/menus (via the [`NavigatorScreen` component](/packages/components/src/navigator/navigator-screen/README.md)) and navigate between these different states (via the [`NavigatorButton`](/packages/components/src/navigator/navigator-button/README.md), [`NavigatorToParentButton`](/packages/components/src/navigator/navigator-to-parent-button/README.md) and [`NavigatorBackButton`](/packages/components/src/navigator/navigator-back-button/README.md) components or the `useNavigator` hook). The Global Styles sidebar is an example of this.
 
 ## Usage
 
@@ -13,7 +13,7 @@ import {
   __experimentalNavigatorProvider as NavigatorProvider,
   __experimentalNavigatorScreen as NavigatorScreen,
   __experimentalNavigatorButton as NavigatorButton,
-  __experimentalNavigatorBackButton as NavigatorBackButton,
+  __experimentalNavigatorToParentButton as NavigatorToParentButton,
 } from '@wordpress/components';
 
 const MyNavigation = () => (
@@ -27,13 +27,21 @@ const MyNavigation = () => (
 
     <NavigatorScreen path="/child">
       <p>This is the child screen.</p>
-      <NavigatorBackButton>
+      <NavigatorToParentButton>
         Go back
-      </NavigatorBackButton>
+      </NavigatorToParentButton>
     </NavigatorScreen>
   </NavigatorProvider>
 );
 ```
+**Important note**
+
+Parent/child navigation only works if the path you define are hierarchical, following a URL-like scheme where each path segment is separated by the `/` character.
+For example:
+- `/` is the root of all paths. There should always be a screen with `path="/"`.
+- `/parent/child` is a child of `/parent`.
+- `/parent/child/grand-child` is a child of `/parent/child`.
+- `/parent/:param` is a child of `/parent` as well.
 
 ## Props
 
@@ -58,6 +66,15 @@ The `goTo` function allows navigating to a given path. The second argument can a
 The available options are:
 
 - `focusTargetSelector`: `string`. An optional property used to specify the CSS selector used to restore focus on the matching element when navigating back.
+- `isBack`: `boolean`. An optional property used to specify whether the navigation should be considered as backwards (thus enabling focus restoration when possible, and causing the animation to be backwards too)
+
+### `goToParent`: `() => void;`
+
+The `goToParent` function allows navigating to the parent screen.
+
+Parent/child navigation only works if the path you define are hierarchical (see note above).
+
+When a match is not found, the function will try to recursively navigate the path hierarchy until a matching screen (or the root `/`) are found.
 
 ### `goBack`: `() => void`
 

packages/components/src/navigator/navigator-provider/component.tsx

@@ -13,6 +13,7 @@ import {
 	useCallback,
 	useReducer,
 	useRef,
+	useEffect,
 } from '@wordpress/element';
 import isShallowEqual from '@wordpress/is-shallow-equal';
 
@@ -33,11 +34,13 @@ import type {
 	NavigatorContext as NavigatorContextType,
 	Screen,
 } from '../types';
-import { patternMatch } from '../utils/router';
+import { patternMatch, findParent } from '../utils/router';
 
 type MatchedPath = ReturnType< typeof patternMatch >;
 type ScreenAction = { type: string; screen: Screen };
 
+const MAX_HISTORY_LENGTH = 50;
+
 function screensReducer(
 	state: Screen[] = [],
 	action: ScreenAction
@@ -66,7 +69,15 @@ function UnconnectedNavigatorProvider(
 			path: initialPath,
 		},
 	] );
+	const currentLocationHistory = useRef< NavigatorLocation[] >( [] );
 	const [ screens, dispatch ] = useReducer( screensReducer, [] );
+	const currentScreens = useRef< Screen[] >( [] );
+	useEffect( () => {
+		currentScreens.current = screens;
+	}, [ screens ] );
+	useEffect( () => {
+		currentLocationHistory.current = locationHistory;
+	}, [ locationHistory ] );
 	const currentMatch = useRef< MatchedPath >();
 	const matchedPath = useMemo( () => {
 		let currentPath: string | undefined;
@@ -115,15 +126,47 @@ function UnconnectedNavigatorProvider(
 		[]
 	);
 
+	const goBack: NavigatorContextType[ 'goBack' ] = useCallback( () => {
+		setLocationHistory( ( prevLocationHistory ) => {
+			if ( prevLocationHistory.length <= 1 ) {
+				return prevLocationHistory;
+			}
+			return [
+				...prevLocationHistory.slice( 0, -2 ),
+				{
+					...prevLocationHistory[ prevLocationHistory.length - 2 ],
+					isBack: true,
+					hasRestoredFocus: false,
+				},
+			];
+		} );
+	}, [] );
+
 	const goTo: NavigatorContextType[ 'goTo' ] = useCallback(
 		( path, options = {} ) => {
-			setLocationHistory( ( prevLocationHistory ) => {
-				const { focusTargetSelector, ...restOptions } = options;
+			const {
+				focusTargetSelector,
+				isBack = false,
+				...restOptions
+			} = options;
+
+			const isNavigatingToPreviousPath =
+				isBack &&
+				currentLocationHistory.current.length > 1 &&
+				currentLocationHistory.current[
+					currentLocationHistory.current.length - 2
+				].path === path;
+
+			if ( isNavigatingToPreviousPath ) {
+				goBack();
+				return;
+			}
 
+			setLocationHistory( ( prevLocationHistory ) => {
 				const newLocation = {
 					...restOptions,
 					path,
-					isBack: false,
+					isBack,
 					hasRestoredFocus: false,
 				};
 
@@ -132,7 +175,12 @@ function UnconnectedNavigatorProvider(
 				}
 
 				return [
-					...prevLocationHistory.slice( 0, -1 ),
+					...prevLocationHistory.slice(
+						prevLocationHistory.length > MAX_HISTORY_LENGTH - 1
+							? 1
+							: 0,
+						-1
+					),
 					// Assign `focusTargetSelector` to the previous location in history
 					// (the one we just navigated from).
 					{
@@ -145,24 +193,27 @@ function UnconnectedNavigatorProvider(
 				];
 			} );
 		},
-		[]
+		[ goBack ]
 	);
 
-	const goBack: NavigatorContextType[ 'goBack' ] = useCallback( () => {
-		setLocationHistory( ( prevLocationHistory ) => {
-			if ( prevLocationHistory.length <= 1 ) {
-				return prevLocationHistory;
+	const goToParent: NavigatorContextType[ 'goToParent' ] =
+		useCallback( () => {
+			const currentPath =
+				currentLocationHistory.current[
+					currentLocationHistory.current.length - 1
+				].path;
+			if ( currentPath === undefined ) {
+				return;
 			}
-			return [
-				...prevLocationHistory.slice( 0, -2 ),
-				{
-					...prevLocationHistory[ prevLocationHistory.length - 2 ],
-					isBack: true,
-					hasRestoredFocus: false,
-				},
-			];
-		} );
-	}, [] );
+			const parentPath = findParent(
+				currentPath,
+				currentScreens.current
+			);
+			if ( parentPath === undefined ) {
+				return;
+			}
+			goTo( parentPath, { isBack: true } );
+		}, [ goTo ] );
 
 	const navigatorContextValue: NavigatorContextType = useMemo(
 		() => ( {
@@ -174,10 +225,19 @@ function UnconnectedNavigatorProvider(
 			match: matchedPath ? matchedPath.id : undefined,
 			goTo,
 			goBack,
+			goToParent,
 			addScreen,
 			removeScreen,
 		} ),
-		[ locationHistory, matchedPath, goTo, goBack, addScreen, removeScreen ]
+		[
+			locationHistory,
+			matchedPath,
+			goTo,
+			goBack,
+			goToParent,
+			addScreen,
+			removeScreen,
+		]
 	);
 
 	const cx = useCx();

packages/components/src/navigator/navigator-to-parent-button/README.md

@@ -0,0 +1,15 @@
+# `NavigatorToParentButton`
+
+<div class="callout callout-alert">
+This feature is still experimental. “Experimental” means this is an early implementation subject to drastic and breaking changes.
+</div>
+
+The `NavigatorToParentButton` component can be used to navigate to a screen and should be used in combination with the [`NavigatorProvider`](/packages/components/src/navigator/navigator-provider/README.md), the [`NavigatorScreen`](/packages/components/src/navigator/navigator-screen/README.md) and the [`NavigatorButton`](/packages/components/src/navigator/navigator-button/README.md) components (or the `useNavigator` hook).
+
+## Usage
+
+Refer to [the `NavigatorProvider` component](/packages/components/src/navigator/navigator-provider/README.md#usage) for a usage example.
+
+### Inherited props
+
+`NavigatorToParentButton` also inherits all of the [`Button` props](/packages/components/src/button/README.md#props), except for `href` and `target`.