Site Editor: Prevent access to the Design/Styles screen from classic themes without StyleBook support

packages/edit-site/src/components/sidebar-navigation-screen-patterns/index.js

@@ -100,7 +100,10 @@ function CategoriesGroup( {
 	);
 }
 
-export default function SidebarNavigationScreenPatterns( { backPath } ) {
+export default function SidebarNavigationScreenPatterns( {
+	isRoot,
+	backPath,
+} ) {
 	const {
 		query: { postType = 'wp_block', categoryId },
 	} = useLocation();
@@ -120,6 +123,7 @@ export default function SidebarNavigationScreenPatterns( { backPath } ) {
 			description={ __(
 				'Manage what patterns are available when editing the site.'
 			) }
+			isRoot={ isRoot }
 			backPath={ backPath }
 			content={
 				<>

packages/edit-site/src/components/sidebar-navigation-screen-unsupported/index.js

@@ -0,0 +1,17 @@
+/**
+ * WordPress dependencies
+ */
+import { __ } from '@wordpress/i18n';
+import { Notice, __experimentalSpacer as Spacer } from '@wordpress/components';
+
+export default function SidebarNavigationScreenUnsupported() {
+	return (
+		<Spacer padding={ 3 }>
+			<Notice status="warning" isDismissible={ false }>
+				{ __(
+					'The theme you are currently using does not support current screen.'
+				) }
+			</Notice>
+		</Spacer>
+	);
+}

packages/edit-site/src/components/site-editor-routes/home.js

@@ -2,14 +2,38 @@
  * Internal dependencies
  */
 import SidebarNavigationScreenMain from '../sidebar-navigation-screen-main';
+import SidebarNavigationScreenUnsupported from '../sidebar-navigation-screen-unsupported';
 import Editor from '../editor';
+import { isClassicThemeWithStyleBookSupport } from './utils';
 
 export const homeRoute = {
 	name: 'home',
 	path: '/',
 	areas: {
-		sidebar: <SidebarNavigationScreenMain />,
-		preview: <Editor isHomeRoute />,
-		mobile: <SidebarNavigationScreenMain />,
+		sidebar( { siteData } ) {
+			const isBlockTheme = siteData.currentTheme?.is_block_theme;
+			return isBlockTheme ||
+				isClassicThemeWithStyleBookSupport( siteData ) ? (
+				<SidebarNavigationScreenMain />
+			) : (
+				<SidebarNavigationScreenUnsupported />
+			);
+		},
+		preview( { siteData } ) {
+			const isBlockTheme = siteData.currentTheme?.is_block_theme;
+			return isBlockTheme ||
+				isClassicThemeWithStyleBookSupport( siteData ) ? (
+				<Editor isHomeRoute />
+			) : undefined;
+		},
+		mobile( { siteData } ) {
+			const isBlockTheme = siteData.currentTheme?.is_block_theme;
+			return isBlockTheme ||
+				isClassicThemeWithStyleBookSupport( siteData ) ? (
+				<SidebarNavigationScreenMain />
+			) : (
+				<SidebarNavigationScreenUnsupported />
+			);
+		},
 	},
 };

packages/edit-site/src/components/site-editor-routes/patterns.js

@@ -1,34 +1,51 @@
-/**
- * WordPress dependencies
- */
-import { privateApis as routerPrivateApis } from '@wordpress/router';
-
 /**
  * Internal dependencies
  */
 import SidebarNavigationScreenPatterns from '../sidebar-navigation-screen-patterns';
 import PagePatterns from '../page-patterns';
-import { unlock } from '../../lock-unlock';
-
-const { useLocation } = unlock( routerPrivateApis );
-
-function MobilePatternsView() {
-	const { query = {} } = useLocation();
-	const { categoryId } = query;
-
-	return !! categoryId ? (
-		<PagePatterns />
-	) : (
-		<SidebarNavigationScreenPatterns backPath="/" />
-	);
-}
+import { isClassicThemeWithStyleBookSupport } from './utils';
 
 export const patternsRoute = {
 	name: 'patterns',
 	path: '/pattern',
 	areas: {
-		sidebar: <SidebarNavigationScreenPatterns backPath="/" />,
+		sidebar( { siteData } ) {
+			const isBlockTheme = siteData.currentTheme?.is_block_theme;
+			const backPath =
+				isBlockTheme || isClassicThemeWithStyleBookSupport( siteData )
+					? '/'
+					: undefined;
+			const isRoot = ! (
+				isBlockTheme || isClassicThemeWithStyleBookSupport( siteData )
+			);
+
+			return (
+				<SidebarNavigationScreenPatterns
+					backPath={ backPath }
+					isRoot={ isRoot }
+				/>
+			);
+		},
 		content: <PagePatterns />,
-		mobile: <MobilePatternsView />,
+		mobile( { siteData, query } ) {
+			const { categoryId } = query;
+			const isBlockTheme = siteData.currentTheme?.is_block_theme;
+			const backPath =
+				isBlockTheme || isClassicThemeWithStyleBookSupport( siteData )
+					? '/'
+					: undefined;
+			const isRoot = ! (
+				isBlockTheme || isClassicThemeWithStyleBookSupport( siteData )
+			);
+
+			return !! categoryId ? (
+				<PagePatterns />
+			) : (
+				<SidebarNavigationScreenPatterns
+					backPath={ backPath }
+					isRoot={ isRoot }
+				/>
+			);
+		},
 	},
 };

packages/edit-site/src/components/site-editor-routes/stylebook.js

@@ -7,22 +7,36 @@ import { __ } from '@wordpress/i18n';
  * Internal dependencies
  */
 import SidebarNavigationScreen from '../sidebar-navigation-screen';
+import SidebarNavigationScreenUnsupported from '../sidebar-navigation-screen-unsupported';
 import { StyleBookPreview } from '../style-book';
+import { isClassicThemeWithStyleBookSupport } from './utils';
 
 export const stylebookRoute = {
 	name: 'stylebook',
 	path: '/stylebook',
 	areas: {
-		sidebar: (
-			<SidebarNavigationScreen
-				title={ __( 'Styles' ) }
-				backPath="/"
-				description={ __(
-					`Preview your website's visual identity: colors, typography, and blocks.`
-				) }
-			/>
-		),
-		preview: <StyleBookPreview isStatic />,
-		mobile: <StyleBookPreview isStatic />,
+		sidebar( { siteData } ) {
+			return isClassicThemeWithStyleBookSupport( siteData ) ? (
+				<SidebarNavigationScreen
+					title={ __( 'Styles' ) }
+					backPath="/"
+					description={ __(
+						`Preview your website's visual identity: colors, typography, and blocks.`
+					) }
+				/>
+			) : (
+				<SidebarNavigationScreenUnsupported />
+			);
+		},
+		preview( { siteData } ) {
+			return isClassicThemeWithStyleBookSupport( siteData ) ? (
+				<StyleBookPreview isStatic />
+			) : undefined;
+		},
+		mobile( { siteData } ) {
+			return isClassicThemeWithStyleBookSupport( siteData ) ? (
+				<StyleBookPreview isStatic />
+			) : undefined;
+		},
 	},
 };

packages/edit-site/src/components/site-editor-routes/utils.js

@@ -0,0 +1,14 @@
+/**
+ * Check if the classic theme supports the stylebook.
+ *
+ * @param {Object} siteData - The site data provided by the site editor route area resolvers.
+ * @return {boolean} True if the stylebook is supported, false otherwise.
+ */
+export function isClassicThemeWithStyleBookSupport( siteData ) {
+	const isBlockTheme = siteData.currentTheme?.is_block_theme;
+	const supportsEditorStyles =
+		siteData.currentTheme?.theme_supports[ 'editor-styles' ];
+	// supportsLayout is equivalent to the `wp_theme_has_theme_json()` PHP function.
+	const hasThemeJson = siteData.editorSettings?.supportsLayout;
+	return ! isBlockTheme && ( supportsEditorStyles || hasThemeJson );
+}

packages/edit-site/src/components/site-hub/index.js

@@ -121,21 +121,47 @@ export const SiteHubMobile = memo(
 		const history = useHistory();
 		const { navigate } = useContext( SidebarNavigationContext );
 
-		const { dashboardLink, homeUrl, siteTitle } = useSelect( ( select ) => {
+		const {
+			dashboardLink,
+			homeUrl,
+			siteTitle,
+			isClassicThemeWithStyleBookSupport,
+		} = useSelect( ( select ) => {
 			const { getSettings } = unlock( select( editSiteStore ) );
-			const { getEntityRecord } = select( coreStore );
+			const { getEntityRecord, getCurrentTheme } = select( coreStore );
 			const _site = getEntityRecord( 'root', 'site' );
+			const isBlockTheme = getCurrentTheme().currentTheme?.is_block_theme;
+			const supportsEditorStyles =
+				getCurrentTheme().theme_supports[ 'editor-styles' ];
+			// supportsLayout is equivalent to the `wp_theme_has_theme_json()` PHP function.
+			const hasThemeJson = getSettings().supportsLayout;
+
 			return {
 				dashboardLink: getSettings().__experimentalDashboardLink,
 				homeUrl: getEntityRecord( 'root', '__unstableBase' )?.home,
 				siteTitle:
 					! _site?.title && !! _site?.url
 						? filterURLForDisplay( _site?.url )
 						: _site?.title,
+				isClassicThemeWithStyleBookSupport:
+					! isBlockTheme && ( supportsEditorStyles || hasThemeJson ),
 			};
 		}, [] );
 		const { open: openCommandCenter } = useDispatch( commandsStore );
-		const isRoot = path === '/';
+		const isRoot = path === '/' || ! isClassicThemeWithStyleBookSupport;
+
+		const backButtonProps = {
+			href: isRoot ? dashboardLink : undefined,
+			label: isRoot
+				? __( 'Go to the Dashboard' )
+				: __( 'Go to Site Editor' ),
+			onClick: isRoot
+				? undefined
+				: () => {
+						history.navigate( '/' );
+						navigate( 'back' );
+				  },
+		};
 
 		return (
 			<div className="edit-site-site-hub">
@@ -156,18 +182,7 @@ export const SiteHubMobile = memo(
 								transform: 'scale(0.5)',
 								borderRadius: 4,
 							} }
-							{ ...( isRoot
-								? {
-										href: dashboardLink,
-										label: __( 'Go to the Dashboard' ),
-								  }
-								: {
-										onClick: () => {
-											history.navigate( '/' );
-											navigate( 'back' );
-										},
-										label: __( 'Go to Site Editor' ),
-								  } ) }
+							{ ...backButtonProps }
 						>
 							<SiteIcon className="edit-site-layout__view-mode-toggle-icon" />
 						</Button>