const sourcesByUrl = {}; const sourcesByPort = {}; class Source { constructor(url) { this.url = url; this.eventSource = new EventSource(url); this.listening = {}; this.clients = []; this.listen('open'); this.listen('close'); this.listen('logout'); this.listen('notification-count'); this.listen('stopwatches'); this.listen('error'); } register(port) { if (this.clients.includes(port)) return; this.clients.push(port); port.postMessage({ type: 'status', message: `registered to ${this.url}`, }); } deregister(port) { const portIdx = this.clients.indexOf(port); if (portIdx < 0) { return this.clients.length; } this.clients.splice(portIdx, 1); return this.clients.length; } close() { if (!this.eventSource) return; this.eventSource.close(); this.eventSource = null; } listen(eventType) { if (this.listening[eventType]) return; this.listening[eventType] = true; const self = this; this.eventSource.addEventListener(eventType, (event) => { self.notifyClients({ type: eventType, data: event.data }); }); } notifyClients(event) { for (const client of this.clients) { client.postMessage(event); } } status(port) { port.postMessage({ type: 'status', message: `url: ${this.url} readyState: ${this.eventSource.readyState}`, }); } } self.onconnect = (e) => { for (const port of e.ports) { port.addEventListener('message', (event) => { if (event.data.type === 'start') { const url = event.data.url; if (sourcesByUrl[url]) { // we have a Source registered to this url const source = sourcesByUrl[url]; source.register(port); sourcesByPort[port] = source; return; } let source = sourcesByPort[port]; if (source) { if (source.eventSource && source.url === url) return; // How this has happened I don't understand... // deregister from that source const count = source.deregister(port); // Clean-up if (count === 0) { source.close(); sourcesByUrl[source.url] = null; } } // Create a new Source source = new Source(url); source.register(port); sourcesByUrl[url] = source; sourcesByPort[port] = source; } else if (event.data.type === 'listen') { const source = sourcesByPort[port]; source.listen(event.data.eventType); } else if (event.data.type === 'close') { const source = sourcesByPort[port]; if (!source) return; const count = source.deregister(port); if (count === 0) { source.close(); sourcesByUrl[source.url] = null; sourcesByPort[port] = null; } } else if (event.data.type === 'status') { const source = sourcesByPort[port]; if (!source) { port.postMessage({ type: 'status', message: 'not connected', }); return; } source.status(port); } else { // just send it back port.postMessage({ type: 'error', message: `received but don't know how to handle: ${event.data}`, }); } }); port.start(); } };