/**
 * Copyright 2012 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/// <reference types="node" />
import { EventEmitter } from 'events';
import { GaxiosOptions, GaxiosPromise } from 'gaxios';
import { DefaultTransporter } from '../transporters';
import { Credentials } from './credentials';
export declare interface AuthClient {
    on(event: 'tokens', listener: (tokens: Credentials) => void): this;
}
export declare abstract class AuthClient extends EventEmitter {
    transporter: DefaultTransporter;
    credentials: Credentials;
    /**
     * Provides an alternative Gaxios request implementation with auth credentials
     */
    abstract request<T>(opts: GaxiosOptions): GaxiosPromise<T>;
    /**
     * Sets the auth credentials.
     */
    setCredentials(credentials: Credentials): void;
}