Add template replace flow to template inspector

packages/base-styles/_z-index.scss

@@ -128,6 +128,7 @@ $z-layers: (
 	".block-editor-block-rename-modal": 1000001,
 	".edit-site-list__rename-modal": 1000001,
 	".edit-site-swap-template-modal": 1000001,
+	".edit-site-template-panel__replace-template-modal": 1000001,
 
 	// Note: The ConfirmDialog component's z-index is being set to 1000001 in packages/components/src/confirm-dialog/styles.ts
 	// because it uses emotion and not sass. We need it to render on top its parent popover.

packages/edit-site/src/components/sidebar-edit-mode/template-panel/hooks.js

@@ -0,0 +1,97 @@
+/**
+ * WordPress dependencies
+ */
+import { useSelect } from '@wordpress/data';
+import { useMemo } from '@wordpress/element';
+import { store as coreStore } from '@wordpress/core-data';
+import { parse } from '@wordpress/blocks';
+
+/**
+ * Internal dependencies
+ */
+import { store as editSiteStore } from '../../../store';
+import { PATTERN_CORE_SOURCES, PATTERN_TYPES } from '../../../utils/constants';
+import { unlock } from '../../../lock-unlock';
+
+function injectThemeAttributeInBlockTemplateContent(
+	block,
+	currentThemeStylesheet
+) {
+	block.innerBlocks = block.innerBlocks.map( ( innerBlock ) => {
+		return injectThemeAttributeInBlockTemplateContent(
+			innerBlock,
+			currentThemeStylesheet
+		);
+	} );
+
+	if (
+		block.name === 'core/template-part' &&
+		block.attributes.theme === undefined
+	) {
+		block.attributes.theme = currentThemeStylesheet;
+	}
+	return block;
+}
+
+function preparePatterns( patterns, template, currentThemeStylesheet ) {
+	// Filter out duplicates.
+	const filterOutDuplicatesByName = ( currentItem, index, items ) =>
+		index === items.findIndex( ( item ) => currentItem.name === item.name );
+
+	// Filter out core patterns.
+	const filterOutCorePatterns = ( pattern ) =>
+		! PATTERN_CORE_SOURCES.includes( pattern.source );
+
+	// Filter only the patterns that are compatible with the current template.
+	const filterCompatiblePatterns = ( pattern ) =>
+		pattern.templateTypes?.includes( template.slug );
+
+	return patterns
+		.filter(
+			filterOutCorePatterns &&
+				filterOutDuplicatesByName &&
+				filterCompatiblePatterns
+		)
+		.map( ( pattern ) => ( {
+			...pattern,
+			keywords: pattern.keywords || [],
+			type: PATTERN_TYPES.theme,
+			blocks: parse( pattern.content, {
+				__unstableSkipMigrationLogs: true,
+			} ).map( ( block ) =>
+				injectThemeAttributeInBlockTemplateContent(
+					block,
+					currentThemeStylesheet
+				)
+			),
+		} ) );
+}
+
+export function useAvailablePatterns( template ) {
+	const { blockPatterns, restBlockPatterns, currentThemeStylesheet } =
+		useSelect( ( select ) => {
+			const { getSettings } = unlock( select( editSiteStore ) );
+			const settings = getSettings();
+
+			return {
+				blockPatterns:
+					settings.__experimentalAdditionalBlockPatterns ??
+					settings.__experimentalBlockPatterns,
+				restBlockPatterns: select( coreStore ).getBlockPatterns(),
+				currentThemeStylesheet:
+					select( coreStore ).getCurrentTheme().stylesheet,
+			};
+		}, [] );
+
+	return useMemo( () => {
+		const mergedPatterns = [
+			...( blockPatterns || [] ),
+			...( restBlockPatterns || [] ),
+		];
+		return preparePatterns(
+			mergedPatterns,
+			template,
+			currentThemeStylesheet
+		);
+	}, [ blockPatterns, restBlockPatterns, template, currentThemeStylesheet ] );
+}

packages/edit-site/src/components/sidebar-edit-mode/template-panel/replace-template-button.js

@@ -0,0 +1,89 @@
+/**
+ * WordPress dependencies
+ */
+import { useSelect, useDispatch } from '@wordpress/data';
+import { useState } from '@wordpress/element';
+import { __experimentalBlockPatternsList as BlockPatternsList } from '@wordpress/block-editor';
+import { MenuItem, Modal } from '@wordpress/components';
+import { __ } from '@wordpress/i18n';
+import { store as coreStore } from '@wordpress/core-data';
+import { useAsyncList } from '@wordpress/compose';
+import { serialize } from '@wordpress/blocks';
+
+/**
+ * Internal dependencies
+ */
+import { store as editSiteStore } from '../../../store';
+
+export default function ReplaceTemplateButton( {
+	onClick,
+	availableTemplates,
+} ) {
+	const { editEntityRecord } = useDispatch( coreStore );
+	const [ showModal, setShowModal ] = useState( false );
+	const onClose = () => {
+		setShowModal( false );
+	};
+
+	const { postId, postType } = useSelect( ( select ) => {
+		return {
+			postId: select( editSiteStore ).getEditedPostId(),
+			postType: select( editSiteStore ).getEditedPostType(),
+		};
+	}, [] );
+
+	const onTemplateSelect = async ( selectedTemplate ) => {
+		onClose(); // Close the template suggestions modal first.
+		onClick();
+		await editEntityRecord( 'postType', postType, postId, {
+			blocks: selectedTemplate.blocks,
+			content: serialize( selectedTemplate.blocks ),
+		} );
+	};
+
+	if ( ! availableTemplates.length || availableTemplates.length < 1 ) {
+		return null;
+	}
+
+	return (
+		<>
+			<MenuItem
+				info={ __(
+					'Replace the contents of this template with another.'
+				) }
+				onClick={ () => setShowModal( true ) }
+			>
+				{ __( 'Replace template' ) }
+			</MenuItem>
+
+			{ showModal && (
+				<Modal
+					title={ __( 'Choose a template' ) }
+					onRequestClose={ onClose }
+					overlayClassName="edit-site-template-panel__replace-template-modal"
+					isFullScreen
+				>
+					<div className="edit-site-template-panel__replace-template-modal__content">
+						<TemplatesList
+							availableTemplates={ availableTemplates }
+							onSelect={ onTemplateSelect }
+						/>
+					</div>
+				</Modal>
+			) }
+		</>
+	);
+}
+
+function TemplatesList( { availableTemplates, onSelect } ) {
+	const shownTemplates = useAsyncList( availableTemplates );
+
+	return (
+		<BlockPatternsList
+			label={ __( 'Templates' ) }
+			blockPatterns={ availableTemplates }
+			shownPatterns={ shownTemplates }
+			onClickPattern={ onSelect }
+		/>
+	);
+}

packages/edit-site/src/components/sidebar-edit-mode/template-panel/style.scss

@@ -37,3 +37,21 @@ h3.edit-site-template-card__template-areas-title {
 	font-weight: 500;
 	margin: 0 0 $grid-unit-10;
 }
+
+
+.edit-site-template-panel__replace-template-modal {
+	z-index: z-index(".edit-site-template-panel__replace-template-modal");
+}
+
+.edit-site-template-panel__replace-template-modal__content {
+	column-count: 2;
+	column-gap: $grid-unit-30;
+
+	@include break-medium() {
+		column-count: 3;
+	}
+
+	@include break-wide() {
+		column-count: 4;
+	}
+}

packages/edit-site/src/components/sidebar-edit-mode/template-panel/template-actions.js

@@ -11,13 +11,21 @@ import { moreVertical } from '@wordpress/icons';
  */
 import { store as editSiteStore } from '../../../store';
 import isTemplateRevertable from '../../../utils/is-template-revertable';
+import ReplaceTemplateButton from './replace-template-button';
+import { useAvailablePatterns } from './hooks';
 
 export default function Actions( { template } ) {
+	const availablePatterns = useAvailablePatterns( template );
 	const { revertTemplate } = useDispatch( editSiteStore );
 	const isRevertable = isTemplateRevertable( template );
-	if ( ! isRevertable ) {
+
+	if (
+		! isRevertable &&
+		( ! availablePatterns.length || availablePatterns.length < 1 )
+	) {
 		return null;
 	}
+
 	return (
 		<DropdownMenu
 			icon={ moreVertical }
@@ -27,17 +35,24 @@ export default function Actions( { template } ) {
 		>
 			{ ( { onClose } ) => (
 				<MenuGroup>
-					<MenuItem
-						info={ __(
-							'Use the template as supplied by the theme.'
-						) }
-						onClick={ () => {
-							revertTemplate( template );
-							onClose();
-						} }
-					>
-						{ __( 'Clear customizations' ) }
-					</MenuItem>
+					{ isRevertable && (
+						<MenuItem
+							info={ __(
+								'Use the template as supplied by the theme.'
+							) }
+							onClick={ () => {
+								revertTemplate( template );
+								onClose();
+							} }
+						>
+							{ __( 'Clear customizations' ) }
+						</MenuItem>
+					) }
+					<ReplaceTemplateButton
+						availableTemplates={ availablePatterns }
+						template={ template }
+						onClick={ onClose }
+					/>
 				</MenuGroup>
 			) }
 		</DropdownMenu>