RocketChat/Rocket.Chat

import type { IUser } from '@rocket.chat/core-typings';
import { Rooms, Subscriptions, Users } from '@rocket.chat/models';

import { notifyOnSubscriptionChangedByRoomId } from '../lib/notifyListener';

const getFname = (members: IUser[]): string => members.map(({ name, username }) => name || username).join(', ');
const getName = (members: IUser[]): string => members.map(({ username }) => username).join(',');

async function getUsersWhoAreInTheSameGroupDMsAs(user: IUser) {
    // add all users to single array so we can fetch details from them all at once
    const rooms = Rooms.findGroupDMsByUids([user._id], { projection: { uids: 1 } });
    if ((await rooms.count()) === 0) {
        return;
    }

    const userIds = new Set();
    const users = new Map();

    await rooms.forEach((room) => {
        if (!room.uids) {
            return;
        }

        room.uids.forEach((uid) => uid !== user._id && userIds.add(uid));
    });

    (await Users.findByIds([...userIds], { projection: { username: 1, name: 1 } }).toArray()).forEach((user: IUser) =>
        users.set(user._id, user),
    );

    return users;
}

function sortUsersAlphabetically(u1: IUser, u2: IUser): number {
    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
    return (u1.name! || u1.username!).localeCompare(u2.name! || u2.username!);
}

export const updateGroupDMsName = async (userThatChangedName: IUser): Promise<void> => {
    if (!userThatChangedName.username) {
        return;
    }

    const users = await getUsersWhoAreInTheSameGroupDMsAs(userThatChangedName);
    if (!users) {
        return;
    }

    users.set(userThatChangedName._id, userThatChangedName);

    const rooms = Rooms.findGroupDMsByUids([userThatChangedName._id], { projection: { uids: 1 } });

    // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
    const getMembers = (uids: string[]) => uids.map((uid) => users.get(uid)).filter(Boolean);

    // loop rooms to update the subscriptions from them all
    for await (const room of rooms) {
        if (!room.uids) {
            return;
        }

        const members = getMembers(room.uids);
        const sortedMembers = members.sort(sortUsersAlphabetically);

        const subs = Subscriptions.findByRoomId(room._id, { projection: { '_id': 1, 'u._id': 1 } });
        for await (const sub of subs) {
            const otherMembers = sortedMembers.filter(({ _id }) => _id !== sub.u._id);
            const updateNameRespose = await Subscriptions.updateNameAndFnameById(sub._id, getName(otherMembers), getFname(otherMembers));
            if (updateNameRespose.modifiedCount) {
                void notifyOnSubscriptionChangedByRoomId(room._id);
            }
        }
    }
};