fix: Deletion of 1st message in a thread causes notification to be up without showing why.

.changeset/ninety-bulldogs-dream.md

@@ -0,0 +1,5 @@
+---
+"@rocket.chat/meteor": minor
+---
+
+Fixes an issue where removing the only thread message of a message would show as if there were unread messages.

apps/meteor/app/lib/server/functions/deleteMessage.ts

@@ -1,14 +1,14 @@
 import { AppEvents, Apps } from '@rocket.chat/apps';
 import { api, Message } from '@rocket.chat/core-services';
-import type { AtLeast, IMessage, IUser } from '@rocket.chat/core-typings';
-import { Messages, Rooms, Uploads, Users, ReadReceipts } from '@rocket.chat/models';
+import type { AtLeast, IMessage, IRoom, IUser } from '@rocket.chat/core-typings';
+import { Messages, Rooms, Uploads, Users, ReadReceipts, Subscriptions } from '@rocket.chat/models';
 import { Meteor } from 'meteor/meteor';
 
 import { callbacks } from '../../../../lib/callbacks';
 import { canDeleteMessageAsync } from '../../../authorization/server/functions/canDeleteMessage';
 import { FileUpload } from '../../../file-upload/server';
 import { settings } from '../../../settings/server';
-import { notifyOnRoomChangedById, notifyOnMessageChange } from '../lib/notifyListener';
+import { notifyOnRoomChangedById, notifyOnMessageChange, notifyOnSubscriptionChangedByRoomIdAndUserId } from '../lib/notifyListener';
 
 export const deleteMessageValidatingPermission = async (message: AtLeast<IMessage, '_id'>, userId: IUser['_id']): Promise<void> => {
 	if (!message?._id) {
@@ -51,7 +51,7 @@ export async function deleteMessage(message: IMessage, user: IUser): Promise<voi
 	}
 
 	if (deletedMsg?.tmid) {
-		await Messages.decreaseReplyCountById(deletedMsg.tmid, -1);
+		await deleteThreadMessage(deletedMsg as Required<Pick<IMessage, 'tmid'>>, user, room);
 	}
 
 	const files = (message.files || [message.file]).filter(Boolean); // Keep compatibility with old messages
@@ -107,3 +107,22 @@ export async function deleteMessage(message: IMessage, user: IUser): Promise<voi
 		void bridges.getListenerBridge().messageEvent(AppEvents.IPostMessageDeleted, deletedMsg, user);
 	}
 }
+
+async function deleteThreadMessage(message: Required<Pick<IMessage, 'tmid'>>, user: IUser, room: IRoom | null): Promise<void> {
+	await Messages.decreaseReplyCountById(message.tmid, -1);
+
+	if (room) {
+		const { modifiedCount } = await Subscriptions.removeUnreadThreadsByRoomId(room._id, [message.tmid]);
+		if (modifiedCount > 0) {
+			void notifyOnSubscriptionChangedByRoomIdAndUserId(room._id, user._id);
+		}
+	}
+
+	// Check if this was the last reply in the thread
+	const thread = await Messages.findOneById(message.tmid, { projection: { tcount: 1 } });
+	if (thread?.tcount === 0) {
+		void notifyOnMessageChange({
+			id: message.tmid,
+		});
+	}
+}

apps/meteor/tests/data/chat.helper.ts

@@ -7,10 +7,12 @@ export const sendSimpleMessage = ({
 	roomId,
 	text = 'test message',
 	tmid,
+	userCredentials = credentials,
 }: {
 	roomId: IRoom['_id'];
 	text?: string;
 	tmid?: IMessage['_id'];
+	userCredentials?: Credentials;
 }) => {
 	if (!roomId) {
 		throw new Error('"roomId" is required in "sendSimpleMessage" test helper');
@@ -28,7 +30,7 @@ export const sendSimpleMessage = ({
 		message.tmid = tmid;
 	}
 
-	return request.post(api('chat.sendMessage')).set(credentials).send({ message });
+	return request.post(api('chat.sendMessage')).set(userCredentials).send({ message });
 };
 
 export const sendMessage = ({

apps/meteor/tests/end-to-end/api/chat.ts

@@ -2005,6 +2005,50 @@ describe('[Chat]', () => {
 				})
 				.end(done);
 		});
+
+		describe('when deleting a thread message', () => {
+			let otherUser: TestUser<IUser>;
+			let otherUserCredentials: Credentials;
+			let parentThreadId: IMessage['_id'];
+
+			before(async () => {
+				otherUser = await createUser();
+				otherUserCredentials = await login(otherUser.username, password);
+				parentThreadId = (await sendSimpleMessage({ roomId: testChannel._id })).body.message._id;
+			});
+
+			after(() => Promise.all([deleteUser(otherUser), deleteMessage({ msgId: parentThreadId, roomId: testChannel._id })]));
+
+			it('should reset the unread counter if the message was removed', async () => {
+				const { body } = await sendSimpleMessage({ roomId: testChannel._id, tmid: parentThreadId, userCredentials: otherUserCredentials });
+				const msgId = body.message._id;
+				await request
+					.post(api('chat.delete'))
+					.set(credentials)
+					.send({
+						roomId: testChannel._id,
+						msgId,
+					})
+					.expect('Content-Type', 'application/json')
+					.expect(200)
+					.expect((res) => {
+						expect(res.body).to.have.property('success', true);
+					});
+				await request
+					.get(api('subscriptions.getOne'))
+					.set(credentials)
+					.query({
+						roomId: testChannel._id,
+					})
+					.expect(200)
+					.expect((res) => {
+						expect(res.body).to.have.property('success', true);
+						expect(res.body.subscription).to.have.property('tunread');
+						expect(res.body.subscription.tunread).to.be.an('array');
+						expect(res.body.subscription.tunread).to.deep.equal([]);
+					});
+			});
+		});
 	});
 
 	describe('/chat.search', () => {