RocketChat/Rocket.Chat

import { MongoClient } from 'mongodb';
import type { Db, Collection, MongoClientOptions, Document } from 'mongodb';

const { MONGO_URL = 'mongodb://localhost:27017/rocketchat' } = process.env;

const name = /^mongodb:\/\/.*?(?::[0-9]+)?\/([^?]*)/.exec(MONGO_URL)?.[1];

export enum Collections {
    Subscriptions = 'rocketchat_subscription',
    UserSession = 'usersSessions',
    User = 'users',
    Trash = 'rocketchat__trash',
    Messages = 'rocketchat_message',
    Rooms = 'rocketchat_room',
    Settings = 'rocketchat_settings',
}

function connectDb(options?: MongoClientOptions): Promise<MongoClient> {
    const client = new MongoClient(MONGO_URL, options);

    return client.connect().catch((error) => {
        // exits the process in case of any error
        console.error(error);
        process.exit(1);
    });
}

let db: Db;

export const getConnection = ((): ((options?: MongoClientOptions) => Promise<Db>) => {
    let client: MongoClient;

    return async (options): Promise<Db> => {
        if (db) {
            return db;
        }
        if (client == null) {
            client = await connectDb(options);
            db = client.db(name);
        }

        // if getConnection was called multiple times before it was connected, wait for the connection
        return client.db(name);
    };
})();

export async function getCollection<T extends Document>(name: Collections): Promise<Collection<T>> {
    if (!db) {
        db = await getConnection();
    }
    return db.collection<T>(name);
}