RocketChat/Rocket.Chat

import type { IMessage } from '@rocket.chat/core-typings';
import { Messages, Rooms } from '@rocket.chat/models';
import type { FindOptions } from 'mongodb';

import { normalizeMessagesForUser } from '../../../utils/server/lib/normalizeMessagesForUser';
import { getHiddenSystemMessages } from '../lib/getHiddenSystemMessages';

export async function loadMessageHistory({
    userId,
    rid,
    end,
    limit = 20,
    ls,
    showThreadMessages = true,
    offset = 0,
}: {
    // userId is undefined if user is reading anonymously
    userId?: string;
    rid: string;
    end: Date | undefined;
    limit?: number;
    ls?: string | Date;
    showThreadMessages?: boolean;
    offset?: number;
}) {
    const room = await Rooms.findOneById(rid, { projection: { sysMes: 1 } });

    if (!room) {
        throw new Error('error-invalid-room');
    }

    const hiddenMessageTypes = getHiddenSystemMessages(room);

    const options: FindOptions<IMessage> = {
        sort: {
            ts: -1,
        },
        limit,
        skip: offset,
    };

    const records = end
        ? await Messages.findVisibleByRoomIdBeforeTimestampNotContainingTypes(
                rid,
                end,
                hiddenMessageTypes,
                options,
                showThreadMessages,
          ).toArray()
        : await Messages.findVisibleByRoomIdNotContainingTypes(rid, hiddenMessageTypes, options, showThreadMessages).toArray();
    const messages = await normalizeMessagesForUser(records, userId);
    let unreadNotLoaded = 0;
    let firstUnread;

    if (ls) {
        const firstMessage = messages[messages.length - 1];

        const lastSeen = new Date(ls);

        if (firstMessage && new Date(firstMessage.ts) > lastSeen) {
            const unreadMessages = Messages.findVisibleByRoomIdBetweenTimestampsNotContainingTypes(
                rid,
                lastSeen,
                firstMessage.ts,
                hiddenMessageTypes,
                {
                    limit: 1,
                    sort: {
                        ts: 1,
                    },
                },
                showThreadMessages,
            );

            const totalCursor = await Messages.countVisibleByRoomIdBetweenTimestampsNotContainingTypes(
                rid,
                lastSeen,
                firstMessage.ts,
                hiddenMessageTypes,
                showThreadMessages,
            );

            firstUnread = (await unreadMessages.toArray())[0];
            unreadNotLoaded = totalCursor;
        }
    }

    return {
        messages,
        firstUnread,
        unreadNotLoaded,
    };
}