fix: unread indicator logic

Author: szuperaz

projects/stream-chat-angular/src/lib/channel.service.spec.ts

@@ -2365,6 +2365,22 @@ describe('ChannelService', () => {
     expect(service.activeChannelUnreadCount).toBe(0);
   });
 
+  it(`should set last read message id to undefined if unread count is 0`, () => {
+    const activeChannel = generateMockChannels()[0];
+    activeChannel.id = 'next-active-channel';
+    activeChannel.state.read[user.id] = {
+      last_read: new Date(),
+      last_read_message_id: 'last-read-message-id',
+      unread_messages: 0,
+      user: user,
+    };
+
+    service.setAsActiveChannel(activeChannel);
+
+    expect(service.activeChannelLastReadMessageId).toBe(undefined);
+    expect(service.activeChannelUnreadCount).toBe(0);
+  });
+
   it('should be able to select empty channel as active channel', () => {
     const channel = generateMockChannels()[0];
     channel.id = 'new-empty-channel';
@@ -2569,6 +2585,18 @@ describe('ChannelService', () => {
 
     expect(service.activeChannelLastReadMessageId).toBe('last-read-message');
     expect(service.activeChannelUnreadCount).toBe(12);
+
+    events$.next({
+      eventType: 'notification.mark_unread',
+      event: {
+        channel_id: service.activeChannel?.id,
+        unread_messages: 0,
+        last_read_message_id: 'last-read-message',
+      } as Event<DefaultStreamChatGenerics>,
+    });
+
+    expect(service.activeChannelLastReadMessageId).toBe(undefined);
+    expect(service.activeChannelUnreadCount).toBe(0);
   });
 
   it('should halt marking the channel as read if an unread call was made in that session', async () => {

projects/stream-chat-angular/src/lib/channel.service.ts

@@ -571,13 +571,14 @@ export class ChannelService<
     const readState =
       channel.state.read[this.chatClientService.chatClient.user?.id || ''];
     this.activeChannelLastReadMessageId = readState?.last_read_message_id;
+    this.activeChannelUnreadCount = readState?.unread_messages || 0;
     if (
       channel.state.latestMessages[channel.state.latestMessages.length - 1]
-        ?.id === this.activeChannelLastReadMessageId
+        ?.id === this.activeChannelLastReadMessageId ||
+      this.activeChannelUnreadCount === 0
     ) {
       this.activeChannelLastReadMessageId = undefined;
     }
-    this.activeChannelUnreadCount = readState?.unread_messages || 0;
     this.watchForActiveChannelEvents(channel);
     this.addChannel(channel);
     this.activeChannelSubject.next(channel);
@@ -1572,6 +1573,9 @@ export class ChannelService<
           this.ngZone.run(() => {
             this.activeChannelLastReadMessageId = e.last_read_message_id;
             this.activeChannelUnreadCount = e.unread_messages;
+            if (this.activeChannelUnreadCount === 0) {
+              this.activeChannelLastReadMessageId = undefined;
+            }
             this.activeChannelSubject.next(this.activeChannel);
           });
         })