From 1fbfe1494f839c408eb0e13df978168162e82f2d Mon Sep 17 00:00:00 2001
From: Zita Szupera <szuperaz@gmail.com>
Date: Tue, 27 Aug 2024 16:44:43 +0200
Subject: [PATCH] fix: unread indicator logic

---
 .../src/lib/channel.service.spec.ts           | 28 +++++++++++++++++++
 .../src/lib/channel.service.ts                |  8 ++++--
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/projects/stream-chat-angular/src/lib/channel.service.spec.ts b/projects/stream-chat-angular/src/lib/channel.service.spec.ts
index ce6dcb5d..10c20d43 100644
--- a/projects/stream-chat-angular/src/lib/channel.service.spec.ts
+++ b/projects/stream-chat-angular/src/lib/channel.service.spec.ts
@@ -2328,6 +2328,22 @@ 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';
@@ -2532,6 +2548,18 @@ 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 () => {
diff --git a/projects/stream-chat-angular/src/lib/channel.service.ts b/projects/stream-chat-angular/src/lib/channel.service.ts
index 1f47d21b..32fede50 100644
--- a/projects/stream-chat-angular/src/lib/channel.service.ts
+++ b/projects/stream-chat-angular/src/lib/channel.service.ts
@@ -557,13 +557,14 @@ 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);
@@ -1513,6 +1514,9 @@ 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);
           });
         })