RocketChat/Rocket.Chat

import type { Db, ReadPreferenceLike } from 'mongodb';
import { ReadPreference } from 'mongodb';

export function readSecondaryPreferred(db?: Db, tags: any[] = []): ReadPreferenceLike {
    const { readPreference } = db?.options || {};

    if (tags.length) {
        return new ReadPreference(ReadPreference.SECONDARY_PREFERRED, tags);
    }
    if (readPreference && readPreference instanceof ReadPreference && readPreference.tags?.length) {
        return new ReadPreference(ReadPreference.SECONDARY_PREFERRED, readPreference.tags);
    }

    // For some reason the new ReadPreference definition requires the tags parameter even not been
    // required by the code implementation and, for some reason, when passing an empty array it
    // doesn't ignore the tags and stop using the secondaries.
    return ReadPreference.SECONDARY_PREFERRED;
}