/**
 * Based on definition by DefinitelyTyped:
 * https://github.com/DefinitelyTyped/DefinitelyTyped/blob/6f529c6c67a447190f86bfbf894d1061e41e07b7/types/http-proxy-middleware/index.d.ts
 */
/// <reference types="node" />
/// <reference types="node" />
/// <reference types="node" />
import type * as http from 'http';
import type * as httpProxy from 'http-proxy';
import type * as net from 'net';
export declare type Request<T = http.IncomingMessage> = T;
export declare type Response<T = http.ServerResponse> = T;
export declare type NextFunction<T = (err?: any) => void> = T;
export interface RequestHandler {
    (req: Request, res: Response, next?: NextFunction): void | Promise<void>;
    upgrade?: (req: Request, socket: net.Socket, head: any) => void;
}
export declare type Filter = string | string[] | ((pathname: string, req: Request) => boolean);
export declare type Plugin = (proxyServer: httpProxy, options: Options) => void;
export declare type OnProxyEvent = {
    error?: httpProxy.ErrorCallback;
    proxyReq?: httpProxy.ProxyReqCallback;
    proxyReqWs?: httpProxy.ProxyReqWsCallback;
    proxyRes?: httpProxy.ProxyResCallback;
    open?: httpProxy.OpenCallback;
    close?: httpProxy.CloseCallback;
    start?: httpProxy.StartCallback;
    end?: httpProxy.EndCallback;
    econnreset?: httpProxy.EconnresetCallback;
};
export declare type Logger = Pick<Console, 'info' | 'warn' | 'error'>;
export interface Options extends httpProxy.ServerOptions {
    /**
     * Narrow down requests to proxy or not.
     * Filter on {@link http.IncomingMessage.url `pathname`} which is relative to the proxy's "mounting" point in the server.
     * Or use the {@link http.IncomingMessage `req`}  object for more complex filtering.
     */
    pathFilter?: Filter;
    pathRewrite?: {
        [regexp: string]: string;
    } | ((path: string, req: Request) => string) | ((path: string, req: Request) => Promise<string>);
    /**
     * Access the internal http-proxy server instance to customize behavior
     *
     * @example
     * ```js
     * createProxyMiddleware({
     *   plugins: [(proxyServer, options) => {
     *     proxyServer.on('error', (error, req, res) => {
     *       console.error(error);
     *     });
     *   }]
     * });
     * ```
     */
    plugins?: Plugin[];
    /**
     * Eject pre-configured plugins.
     * NOTE: register your own error handlers to prevent server from crashing.
     *
     * @since v3.0.0
     */
    ejectPlugins?: boolean;
    /**
     * Listen to http-proxy events
     * @see {@link OnProxyEvent} for available events
     * @example
     * ```js
     * createProxyMiddleware({
     *   on: {
     *     error: (error, req, res, target) => {
     *       console.error(error);
     *     }
     *   }
     * });
     * ```
     */
    on?: OnProxyEvent;
    router?: {
        [hostOrPath: string]: httpProxy.ServerOptions['target'];
    } | ((req: Request) => httpProxy.ServerOptions['target']) | ((req: Request) => Promise<httpProxy.ServerOptions['target']>);
    /**
     * Log information from http-proxy-middleware
     * @example
     * ```js
     * createProxyMiddleware({
     *  logger: console
     * });
     * ```
     */
    logger?: Logger | any;
}