import { Request, Response } from "express";
import { Context } from "../../types";
/**
 * Originally forked from sse-pubsub:
 *   https://www.npmjs.com/package/sse-pubsub
 *   Copyright for portions of project GrowthBook Proxy are held by Andrew Betts, 2017
 *   All other copyright is held by GrowthBook, Inc., 2022
 */
export interface Options {
    pingInterval: number;
    maxStreamDuration: number;
    clientRetryInterval: number;
    startId: number;
    historySize: number;
    rewind: number;
}
interface Connection {
    req: Request;
    res: Response;
    events?: (string | RegExp)[];
}
export declare class SSEChannel {
    private nextID;
    private clients;
    private messages;
    private active;
    private pingTimer;
    private options;
    private appContext?;
    constructor({ pingInterval, maxStreamDuration, clientRetryInterval, startId, historySize, rewind, }: Partial<Options>, appContext?: Context);
    publish(data?: any, eventName?: string): number | undefined;
    subscribe(req: Request, res: Response, events?: (string | RegExp)[]): Connection;
    unsubscribe(c: Connection): void;
    close(): void;
    listClients(): Record<string, number>;
    getSubscriberCount(): number;
    private hasEventMatch;
}
export {};