Site Editor Compatibility: Podcast Player block issues in editor and front end views

projects/plugins/jetpack/changelog/fix-site-editor-podcast-player-block

@@ -0,0 +1,4 @@
+Significance: patch
+Type: compat
+
+Ensure compatibility with the Site Editor by injecting required media assets into the Site Editor canvas, and loading frontend scripts onDomReady

projects/plugins/jetpack/extensions/blocks/podcast-player/edit.js

@@ -7,7 +7,7 @@ import { debounce, noop } from 'lodash';
 /**
  * WordPress dependencies
  */
-import { useCallback, useEffect, useRef, useReducer } from '@wordpress/element';
+import { useCallback, useEffect, useState, useRef, useReducer } from '@wordpress/element';
 import {
 	Button,
 	ExternalLink,
@@ -50,6 +50,7 @@ import { fetchPodcastFeed } from './api';
 import { podcastPlayerReducer, actions } from './state';
 import { applyFallbackStyles } from '../../shared/apply-fallback-styles';
 import { PODCAST_FEED, EMBED_BLOCK } from './constants';
+import { maybeCopyElementsToSiteEditorContext } from '../../shared/block-editor-asset-loader';
 
 const DEFAULT_MIN_ITEMS = 1;
 const DEFAULT_MAX_ITEMS = 10;
@@ -94,6 +95,8 @@ const PodcastPlayerEdit = ( {
 
 	const playerId = `jetpack-podcast-player-block-${ instanceId }`;
 
+	const [ hasMigratedStyles, setHasMigratedStyles ] = useState( false );
+
 	// State.
 	const cancellableFetch = useRef();
 	const [ { selectedGuid, checkUrl, ...state }, dispatch ] = useReducer( podcastPlayerReducer, {
@@ -156,12 +159,28 @@ const PodcastPlayerEdit = ( {
 		[ replaceWithEmbedBlock, setAttributes ]
 	);
 
+	// Call once on mount or unmount (the return callback).
 	useEffect( () => {
 		return () => {
 			cancellableFetch?.current?.cancel?.();
 		};
 	}, [] );
 
+	// The Podcast player audio element requires wpmedialement styles.
+	// These aren't available in the Site Editor context, so we have to copy them in.
+	const podCastPlayerRef = useCallback(
+		node => {
+			if ( node !== null && ! hasMigratedStyles ) {
+				maybeCopyElementsToSiteEditorContext(
+					[ 'link#mediaelement-css', 'link#wp-mediaelement-css' ],
+					node
+				);
+				setHasMigratedStyles( true );
+			}
+		},
+		[ hasMigratedStyles ]
+	);
+
 	// Load RSS feed initially and when the feed or selected episode changes.
 	useEffect( () => {
 		// Don't do anything if no url is set.
@@ -374,7 +393,7 @@ const PodcastPlayerEdit = ( {
 				</PanelColorSettings>
 			</InspectorControls>
 
-			<div id={ playerId } className={ className }>
+			<div id={ playerId } className={ className } ref={ podCastPlayerRef }>
 				<PodcastPlayer
 					playerId={ playerId }
 					attributes={ validatedAttributes }

projects/plugins/jetpack/extensions/blocks/podcast-player/view.js

@@ -96,9 +96,11 @@ const initializeBlock = function ( id ) {
 	block.setAttribute( 'data-jetpack-block-initialized', 'true' );
 };
 
-document
-	.querySelectorAll( '.wp-block-jetpack-podcast-player:not([data-jetpack-block-initialized])' )
-	.forEach( player => {
-		player.classList.remove( 'is-default' );
-		initializeBlock( player.id );
-	} );
+document.addEventListener( 'DOMContentLoaded', () => {
+	document
+		.querySelectorAll( '.wp-block-jetpack-podcast-player:not([data-jetpack-block-initialized])' )
+		.forEach( player => {
+			player.classList.remove( 'is-default' );
+			initializeBlock( player.id );
+		} );
+} );

projects/plugins/jetpack/extensions/shared/block-editor-asset-loader.js

@@ -0,0 +1,94 @@
+/**
+ * Returns the current document and window contexts for `elementRef`.
+ * Use to retrieve the correct context for elements that may be within an iframe.
+ *
+ * @param   {HTMLElement} elementRef - The element whose context we want to return.
+ * @returns {Object}                 - The current document (`currentDoc`) and window (`currentWindow`) contexts.
+ */
+export function getLoadContext( elementRef ) {
+	const currentDoc = elementRef.ownerDocument;
+	const currentWindow = currentDoc.defaultView || currentDoc.parentWindow;
+
+	return { currentDoc, currentWindow };
+}
+
+/**
+ * Returns whether a given element is contained within an Editor iframe.
+ * See: https://github.com/WordPress/gutenberg/blob/bee52e68292357011a799f067ad47aa1c1d710e1/packages/block-editor/src/components/iframe/index.js
+ *
+ * @param   {HTMLElement} elementRef - The element whose context we want to return.
+ * @returns {boolean}                - Whether `elementRef` is contained within an Editor iframe.
+ */
+export function isElementInEditorIframe( elementRef ) {
+	const { currentWindow } = getLoadContext( elementRef );
+	return currentWindow.name === 'editor-canvas' && currentWindow.self !== currentWindow.top;
+}
+
+/**
+ * Returns whether a iframe has domain access to its parent.
+ *
+ * @param   {HTMLElement} currentWindow - The window context for which we want to test access.
+ * @returns {boolean}                   - Whether we have access to the parent window.
+ */
+function canIframeAccessParentWindow( currentWindow ) {
+	try {
+		return !! currentWindow?.parent?.location.href;
+	} catch ( e ) {
+		return false;
+	}
+}
+
+/**
+ * This function will check if the current element (e.g., a block) sits inside an Iframe (e.g., the Site Editor)
+ * and tries to move elements from the parent window to the iframe.
+ *
+ * It's a temporary work-around to inject the styles we need for the media player into the site editor.
+ * For use until Gutenberg offers a standardized way of including enqueued/3rd-party assets.
+ * Target usage is the Podcast Playerblock: projects/plugins/jetpack/extensions/blocks/podcast-player/.
+ *
+ * @param   {Array}       elementSelectors   - An array of selectors, e.g., [ '#conan', '#robocop' ]
+ * @param   {HTMLElement} elementRef         - The current element.
+ * @param   {boolean}     shouldRemoveSource - Optional. Whether to remove the source element in the parent frame.
+ * @returns {Array}                          - An array of successfully migrated selectors;
+ */
+export function maybeCopyElementsToSiteEditorContext(
+	elementSelectors,
+	elementRef,
+	shouldRemoveSource = false
+) {
+	let results = [];
+	// Check to see if we're in an iframe, e.g., the Site Editor.
+	// If not, do nothing.
+	if (
+		! elementRef ||
+		( ! elementSelectors && ! elementSelectors.length ) ||
+		! isElementInEditorIframe( elementRef )
+	) {
+		return results;
+	}
+
+	const { currentDoc, currentWindow } = getLoadContext( elementRef );
+
+	if ( ! canIframeAccessParentWindow( currentWindow ) ) {
+		return results;
+	}
+
+	const parentDoc = currentWindow?.parent?.document;
+
+	if ( currentDoc && parentDoc ) {
+		results = elementSelectors.filter( selector => {
+			const parentElementToCopy = parentDoc.querySelector( selector );
+			const isElementAlreadyPresentInCurrentWindow = !! currentDoc.querySelector( selector );
+			if ( parentElementToCopy && ! isElementAlreadyPresentInCurrentWindow ) {
+				currentDoc.head.appendChild( parentElementToCopy.cloneNode() );
+				if ( shouldRemoveSource ) {
+					parentElementToCopy.remove();
+				}
+				return true;
+			}
+			return false;
+		} );
+
+		return results;
+	}
+}