Post session info to service worker instead of asking from sw (#2605)

post session info to service worker instead of asking from sw on each request

src/sw.ts

@@ -3,22 +3,64 @@
 export type {};
 declare const self: ServiceWorkerGlobalScope;
 
-async function askForAccessToken(client: Client): Promise<string | undefined> {
-  return new Promise((resolve) => {
-    const responseKey = Math.random().toString(36);
-    const listener = (event: ExtendableMessageEvent) => {
-      if (event.data.responseKey !== responseKey) return;
-      resolve(event.data.token);
-      self.removeEventListener('message', listener);
-    };
-    self.addEventListener('message', listener);
-    client.postMessage({ responseKey, type: 'token' });
+self.addEventListener('install', () => {
+  self.skipWaiting();
+});
+
+self.addEventListener('activate', (event: ExtendableEvent) => {
+  event.waitUntil(self.clients.claim());
+});
+
+type SessionInfo = {
+  accessToken: string;
+  baseUrl: string;
+};
+
+/**
+ * Store session per client (tab)
+ */
+const sessions = new Map<string, SessionInfo>();
+
+async function cleanupDeadClients() {
+  const activeClients = await self.clients.matchAll();
+  const activeIds = new Set(activeClients.map((c) => c.id));
+
+  Array.from(sessions.keys()).forEach((id) => {
+    if (!activeIds.has(id)) {
+      sessions.delete(id);
+    }
   });
 }
 
-function fetchConfig(token?: string): RequestInit | undefined {
-  if (!token) return undefined;
+/**
+ * Receive session updates from clients
+ */
+self.addEventListener('message', (event: ExtendableMessageEvent) => {
+  const client = event.source as Client | null;
+  if (!client) return;
 
+  const { type, accessToken, baseUrl } = event.data || {};
+
+  if (type !== 'setSession') return;
+
+  cleanupDeadClients();
+
+  if (typeof accessToken === 'string' && typeof baseUrl === 'string') {
+    sessions.set(client.id, { accessToken, baseUrl });
+  } else {
+    // Logout or invalid session
+    sessions.delete(client.id);
+  }
+});
+
+function validMediaRequest(url: string, baseUrl: string): boolean {
+  const downloadUrl = new URL('/_matrix/client/v1/media/download', baseUrl);
+  const thumbnailUrl = new URL('/_matrix/client/v1/media/thumbnail', baseUrl);
+
+  return url.startsWith(downloadUrl.href) || url.startsWith(thumbnailUrl.href);
+}
+
+function fetchConfig(token: string): RequestInit {
   return {
     headers: {
       Authorization: `Bearer ${token}`,
@@ -27,26 +69,16 @@ function fetchConfig(token?: string): RequestInit | undefined {
   };
 }
 
-self.addEventListener('activate', (event: ExtendableEvent) => {
-  event.waitUntil(clients.claim());
-});
-
 self.addEventListener('fetch', (event: FetchEvent) => {
   const { url, method } = event.request;
-  if (method !== 'GET') return;
-  if (
-    !url.includes('/_matrix/client/v1/media/download') &&
-    !url.includes('/_matrix/client/v1/media/thumbnail')
-  ) {
-    return;
-  }
-  event.respondWith(
-    (async (): Promise<Response> => {
-      const client = await self.clients.get(event.clientId);
-      let token: string | undefined;
-      if (client) token = await askForAccessToken(client);
 
-      return fetch(url, fetchConfig(token));
-    })()
-  );
+  if (method !== 'GET') return;
+  if (!event.clientId) return;
+
+  const session = sessions.get(event.clientId);
+  if (!session) return;
+
+  if (!validMediaRequest(url, session.baseUrl)) return;
+
+  event.respondWith(fetch(url, fetchConfig(session.accessToken)));
 });