Restore some eventSource code

packages/host/app/services/message-service.ts

@@ -1,9 +1,17 @@
 import Service, { service } from '@ember/service';
 
+import { isTesting } from '@embroider/macros';
+
 import { tracked } from '@glimmer/tracking';
 
+import window from 'ember-window-mock';
+
+import qs from 'qs';
+
 import type { RealmEventEventContent } from 'https://cardstack.com/base/matrix-event';
 
+import { SessionLocalStorageKey } from '../utils/local-storage-keys';
+
 import type NetworkService from './network';
 
 export default class MessageService extends Service {
@@ -26,14 +34,46 @@ export default class MessageService extends Service {
       this.listenerCallbacks.set(realmURL, []);
     }
     this.listenerCallbacks.get(realmURL)?.push(cb);
+
+    let maybeEventSource = this.subscriptions.get(realmURL);
+
+    if (!maybeEventSource) {
+      let token = getPersistedTokenForRealm(realmURL);
+      if (!token) {
+        throw new Error(`Could not find JWT for realm ${realmURL}`);
+      }
+      let urlWithAuth = `${realmURL}_message?${qs.stringify({
+        authHeader: 'Bearer ' + token,
+      })}`;
+      maybeEventSource = this.network.createEventSource(urlWithAuth);
+
+      if (maybeEventSource) {
+        maybeEventSource.onerror = () => maybeEventSource?.close();
+        maybeEventSource.onmessage = (ev) => {
+          throw new Error('received unexpected server-sent event: ' + ev);
+        };
+
+        this.subscriptions.set(realmURL, maybeEventSource);
+      }
+    }
+
     return () => {};
   }
 
   relayMatrixSSE(realmURL: string, event: RealmEventEventContent) {
     console.log('relaying matrix sse event', realmURL, event);
-    console.log('listener callbacks', this.listenerCallbacks);
     this.listenerCallbacks.get(realmURL)?.forEach((cb) => {
       cb(event);
     });
   }
 }
+
+function getPersistedTokenForRealm(realmURL: string) {
+  if (isTesting()) {
+    return 'TEST_TOKEN';
+  }
+
+  let sessionStr = window.localStorage.getItem(SessionLocalStorageKey) ?? '{}';
+  let session = JSON.parse(sessionStr);
+  return session[realmURL] as string | undefined;
+}