import { EventEmitter } from 'node:events';
import { AnyFunction, AnyJson, JsonMap } from '@salesforce/ts-types';
export type Message = JsonMap;
export type Callback<T = unknown> = (...args: any[]) => T;
export type StatusResult = {
    /**
     * If the result of the streaming or polling client is expected to return a result
     */
    payload?: AnyJson;
    /**
     * Indicates to the streaming or polling client that the subscriber has what its needs. If `true` the client will end
     * the messaging exchanges with the endpoint.
     */
    completed: boolean;
};
/**
 * The subscription object returned from the cometd subscribe object.
 */
export type CometSubscription = {
    callback(callback: () => void): void;
    errback(callback: (error: Error) => void): void;
};
/**
 * Types for defining extensions.
 */
export type StreamingExtension = {
    /**
     * Extension for outgoing message.
     *
     * @param message The message.
     * @param callback The callback to invoke after the message is processed.
     */
    outgoing?: (message: JsonMap, callback: AnyFunction) => void;
    /**
     * Extension for the incoming message.
     *
     * @param message The message.
     * @param callback The callback to invoke after the message is processed.
     */
    incoming?: (message: JsonMap, callback: AnyFunction) => void;
};
/**
 * Function type for processing messages
 */
export declare type StreamProcessor = (message: JsonMap) => StatusResult;
/**
 * Comet client interface. The is to allow for mocking the inner streaming Cometd implementation.
 * The Faye implementation is used by default but it could be used to adapt another Cometd impl.
 */
export declare abstract class CometClient extends EventEmitter {
    /**
     * Disable polling features.
     *
     * @param label Polling feature label.
     */
    abstract disable(label: string): void;
    /**
     * Add a custom extension to the underlying client.
     *
     * @param extension The json function for the extension.
     */
    abstract addExtension(extension: StreamingExtension): void;
    /**
     * Sets an http header name/value.
     *
     * @param name The header name.
     * @param value The header value.
     */
    abstract setHeader(name: string, value: string): void;
    /**
     * handshake with the streaming channel
     *
     * @param callback Callback for the handshake when it successfully completes. The handshake should throw
     * errors when errors are encountered.
     */
    abstract handshake(callback: () => void): void;
    /**
     * Subscribes to Comet topics. Subscribe should perform a handshake if one hasn't been performed yet.
     *
     * @param channel The topic to subscribe to.
     * @param callback The callback to execute once a message has been received.
     */
    abstract subscribe(channel: string, callback: (message: JsonMap) => void): CometSubscription;
    /**
     * Method to call to disconnect the client from the server.
     */
    abstract disconnect(): void;
}