import type { CollectionReference } from '@google-cloud/firestore';
import type { Context, Middleware } from 'telegraf';
interface Options<C> {
    getSessionKey: (ctx: C) => string | undefined;
    lazy: boolean | Promise<boolean> | ((ctx: C) => boolean) | ((ctx: C) => Promise<boolean>);
}
declare function middleware<C extends Context>(collection: CollectionReference, opts?: Partial<Options<C>>): Middleware<C>;
export = middleware;