Merge pull request #4034 from G-Ambatte/experimentalEventStreamEmitter

Experimental event stream emitter

client/homebrew/homebrew.jsx

@@ -1,6 +1,5 @@
 import 'core-js/es/string/to-well-formed.js'; // Polyfill for older browsers
 import './homebrew.less';
-import React from 'react';
 import { BrowserRouter as Router, Routes, Route, useParams, useSearchParams } from 'react-router';
 
 import { updateLocalStorage } from './utils/updateLocalStorage/updateLocalStorageKeys.js';

client/homebrew/pages/sharePage/sharePage.jsx

@@ -39,6 +39,18 @@ const SharePage = (props)=>{
 		document.addEventListener('keydown', handleControlKeys);
 		fetchThemeBundle(undefined, setThemeBundle, brew.renderer, brew.theme);
 
+        // listen for changes in the brew version
+		const eventSource = new EventSource('/stream');
+		eventSource.addEventListener('message', (evt)=>{
+			const messageData = JSON.parse(evt.data);
+
+			if(messageData.eventType == 'brewUpdated'){
+				if(messageData.shareId == brew.shareId && messageData.version != brew.version) {
+					console.log(`brew has been updated, viewing ${brew.version}, new version is ${messageData.version}`);
+				}
+			}
+		});
+
 		return ()=>{
 			document.removeEventListener('keydown', handleControlKeys);
 		};

server/app.js

@@ -1,4 +1,4 @@
-/*eslint max-lines: ["warn", {"max": 500, "skipBlankLines": true, "skipComments": true}]*/
+/*eslint max-lines: ["warn", {"max": 400, "skipBlankLines": true, "skipComments": true}]*/
 // Set working directory to project root
 import { dirname }       from 'path';
 import { fileURLToPath } from 'url';
@@ -30,6 +30,8 @@ import contentNegotiation from './middleware/content-negotiation.js';
 import bodyParser         from 'body-parser';
 import cookieParser       from 'cookie-parser';
 import forceSSL           from './forcessl.mw.js';
+
+import Stream from './eventStreamSource.js';
 import dbCheck            from './middleware/dbCheck.js';
 
 import cors from 'cors';
@@ -124,10 +126,10 @@ export default async function createApp(vite) {
 	};
 
 	app.use(pageRoutes({
-        defaultMetaTags,
+		defaultMetaTags,
 		HomebrewModel,
 		sanitizeBrew,
-    }));
+	}));
 
 	//Robots.txt
 	app.get('/robots.txt', (req, res)=>{
@@ -182,6 +184,27 @@ export default async function createApp(vite) {
 		}
 	});
 
+	// Create Event Stream source for pages to listen to
+	app.get('/stream', (req, res)=>{
+		res.writeHead(200, {
+			'Content-Type'     : 'text/event-stream',
+			'Cache-Control'    : 'no-cache',
+			'Connection'       : 'keep-alive',
+			'Content-Encoding' : 'none'
+		});
+
+		Stream.on('sendUpdate', (event, data)=>{
+			console.log('Event:', event, '\nData:', data);
+			res.write(`data: ${JSON.stringify({ ...data, eventType: event })}\n\n`);
+		});
+	});
+
+	// After Stream starts, send initStream event
+	setTimeout(()=>{
+		Stream.emit('sendUpdate', 'initStream', { time: new Date });
+	}, 1000);
+
+
 	// Local only
 	if(isLocalEnvironment){
 	// Login

server/eventStreamSource.js

@@ -0,0 +1,9 @@
+import { EventEmitter } from 'events';
+
+const Stream = new EventEmitter;
+
+export default {
+	emit : function(event) {return Stream.emit(event, ...([...arguments].slice(1)));},    // Arguments doesn't work for arrow functions
+	on   : (event, listener)=>{return Stream.on(event, listener);},
+	off  : (event, listener)=>{return Stream.off(event, listener);}
+};

server/homebrew.api.js

@@ -21,6 +21,8 @@ const router = express.Router();
 import { DEFAULT_BREW, DEFAULT_BREW_LOAD } from './brewDefaults.js';
 import Themes from '../themes/themes.json' with { type: 'json' };
 
+import Stream from './eventStreamSource.js';
+
 const isStaticTheme = (renderer, themeName)=>{
 	return Themes[renderer]?.[themeName] !== undefined;
 };
@@ -500,6 +502,8 @@ const api = {
 
 		saved.textBin = undefined; // Remove textBin from the saved object to save bandwidth
 
+		Stream.emit('sendUpdate', 'brewUpdated', { time: new Date, shareId: brew.shareId, version: brew.version });
+
 		res.status(200).send(saved);
 	},
 	deleteGoogleBrew : async (account, id, editId, res)=>{