Rocket.Chat/apps/meteor/app/api/server/helpers/getLoggedInUser.ts

import type { IUser } from '@rocket.chat/core-typings';
import { Users } from '@rocket.chat/models';
import { Accounts } from 'meteor/accounts-base';

export async function getLoggedInUser(request: Request): Promise<Pick<IUser, '_id' | 'username'> | null> {
	const token = request.headers.get('x-auth-token');
	const userId = request.headers.get('x-user-id');
	if (!token || !userId || typeof token !== 'string' || typeof userId !== 'string') {
		return null;
	}

	return Users.findOneByIdAndLoginToken(userId, Accounts._hashLoginToken(token), { projection: { username: 1 } });
}