/// <reference types="express" />
import { Request, Response, NextFunction } from "express";
export declare type GuardCallback = (req: Request, res: Response, next: NextFunction, error?: any, data?: any) => void;
export interface GuardOptions {
    userIdOnly: boolean;
    tokenField: string;
}
export declare class Guard {
    private callback;
    private options;
    constructor(serviceAccount: any);
    constructor(serviceAccount: any, options: GuardOptions);
    constructor(serviceAccount: any, callback: GuardCallback);
    constructor(serviceAccount: any, options: GuardOptions, callback: GuardCallback);
    middleware: (req: Request, res: Response, next: NextFunction) => void;
    private fetchUserInfo;
}