[PM-22573] Don't call server on existing subscription (#15154)

* Don't put subscription to our server when it's existing

* Only update server when subscription-user associations change

---------

Co-authored-by: Matt Gibson <mgibson@bitwarden.com>

libs/common/src/platform/notifications/internal/worker-webpush-connection.service.ts

@@ -9,6 +9,7 @@ import {
   Subject,
   Subscription,
   switchMap,
+  withLatestFrom,
 } from "rxjs";
 
 import { PushTechnology } from "../../../enums/push-technology.enum";
@@ -17,6 +18,7 @@ import { UserId } from "../../../types/guid";
 import { ConfigService } from "../../abstractions/config/config.service";
 import { SupportStatus } from "../../misc/support-status";
 import { Utils } from "../../misc/utils";
+import { KeyDefinition, StateProvider, WEB_PUSH_SUBSCRIPTION } from "../../state";
 
 import { WebPushNotificationsApiService } from "./web-push-notifications-api.service";
 import { WebPushConnectionService, WebPushConnector } from "./webpush-connection.service";
@@ -48,6 +50,7 @@ export class WorkerWebPushConnectionService implements WebPushConnectionService
     private readonly configService: ConfigService,
     private readonly webPushApiService: WebPushNotificationsApiService,
     private readonly serviceWorkerRegistration: ServiceWorkerRegistration,
+    private readonly stateProvider: StateProvider,
   ) {}
 
   start(): Subscription {
@@ -97,6 +100,7 @@ export class WorkerWebPushConnectionService implements WebPushConnectionService
             this.serviceWorkerRegistration,
             this.pushEvent,
             this.pushChangeEvent,
+            this.stateProvider,
           ),
         } satisfies SupportStatus<WebPushConnector>;
       }),
@@ -114,20 +118,36 @@ class MyWebPushConnector implements WebPushConnector {
     private readonly serviceWorkerRegistration: ServiceWorkerRegistration,
     private readonly pushEvent$: Observable<PushEvent>,
     private readonly pushChangeEvent$: Observable<PushSubscriptionChangeEvent>,
+    private readonly stateProvider: StateProvider,
   ) {
+    const subscriptionUsersState = this.stateProvider.getGlobal(WEB_PUSH_SUBSCRIPTION_USERS);
     this.notifications$ = this.getOrCreateSubscription$(this.vapidPublicKey).pipe(
-      concatMap((subscription) => {
-        return defer(() => {
-          if (subscription == null) {
-            throw new Error("Expected a non-null subscription.");
-          }
-          return this.webPushApiService.putSubscription(subscription.toJSON());
-        }).pipe(
-          switchMap(() => this.pushEvent$),
-          map((e) => {
-            return new NotificationResponse(e.data.json().data);
-          }),
-        );
+      withLatestFrom(subscriptionUsersState.state$.pipe(map((x) => x ?? {}))),
+      concatMap(async ([[isExistingSubscription, subscription], subscriptionUsers]) => {
+        if (subscription == null) {
+          throw new Error("Expected a non-null subscription.");
+        }
+
+        // If this is a new subscription, we can clear state and start over
+        if (!isExistingSubscription) {
+          subscriptionUsers = {};
+        }
+
+        // If the user is already subscribed, we don't need to do anything
+        if (subscriptionUsers[subscription.endpoint]?.includes(this.userId)) {
+          return;
+        }
+        subscriptionUsers[subscription.endpoint] ??= [];
+        subscriptionUsers[subscription.endpoint].push(this.userId);
+        // Update the state with the new subscription-user association
+        await subscriptionUsersState.update(() => subscriptionUsers);
+
+        // Inform the server about the new subscription-user association
+        await this.webPushApiService.putSubscription(subscription.toJSON());
+      }),
+      switchMap(() => this.pushEvent$),
+      map((e) => {
+        return new NotificationResponse(e.data.json().data);
       }),
     );
   }
@@ -146,7 +166,7 @@ class MyWebPushConnector implements WebPushConnector {
           await this.serviceWorkerRegistration.pushManager.getSubscription();
 
         if (existingSubscription == null) {
-          return await this.pushManagerSubscribe(key);
+          return [false, await this.pushManagerSubscribe(key)] as const;
         }
 
         const subscriptionKey = Utils.fromBufferToUrlB64(
@@ -159,12 +179,30 @@ class MyWebPushConnector implements WebPushConnector {
         if (subscriptionKey !== key) {
           // There is a subscription, but it's not for the current server, unsubscribe and then make a new one
           await existingSubscription.unsubscribe();
-          return await this.pushManagerSubscribe(key);
+          return [false, await this.pushManagerSubscribe(key)] as const;
         }
 
-        return existingSubscription;
+        return [true, existingSubscription] as const;
       }),
-      this.pushChangeEvent$.pipe(map((event) => event.newSubscription)),
+      this.pushChangeEvent$.pipe(map((event) => [false, event.newSubscription] as const)),
     );
   }
 }
+
+export const WEB_PUSH_SUBSCRIPTION_USERS = new KeyDefinition<Record<string, UserId[]>>(
+  WEB_PUSH_SUBSCRIPTION,
+  "subUsers",
+  {
+    deserializer: (obj) => {
+      if (obj == null) {
+        return {};
+      }
+
+      const result: Record<string, UserId[]> = {};
+      for (const [key, value] of Object.entries(obj)) {
+        result[key] = Array.isArray(value) ? value : [];
+      }
+      return result;
+    },
+  },
+);