/// <reference types="node" />
/**
 * @packageDocumentation
 */
import * as event from "./event";
/**
 * Converts payload to Buffer or string regardless of the supplied type
 * @param payload The payload to convert
 * @internal
 */
export declare function normalize_payload(payload: any): Buffer | string;
/**
 * Converts payload to Buffer only, regardless of the supplied type
 * @param payload The payload to convert
 * @internal
 */
export declare function normalize_payload_to_buffer(payload: any): Buffer;
/** @internal */
export declare const DEFAULT_KEEP_ALIVE: number;
export declare function isValidTopicFilter(topicFilter: any): boolean;
export declare function isValidTopic(topic: any): boolean;
export type PublishAcknowledgementFunctor = () => void;
/**
 * Wrapper class containing a one-use singleton handle that can be used to trigger sending the acknowledgement (Puback in
 * QoS 1, Pubrec in QoS 2) packet for an incoming publish.
 */
export declare class PublishAcknowledgementHandleWrapper {
    private ackHandle;
    constructor(handle: PublishAcknowledgementHandle | null);
    /**
     * Attempt to take the acknowledgement handle held by the wrapper.  This will only succeed for the first caller;
     * after the initial call, null will be returned.  By taking the handle, the caller assumes responsibility
     * for sending the acknowledgement packet associated with the incoming publish packet.  Failing to trigger the
     * acknowledgement will cause the broker to potentially re-send the publish.
     */
    acquireHandle(): PublishAcknowledgementHandle | null;
}
/** @internal */
export declare function emitAcknowledgeableEvent<T>(emitter: event.BufferedEventEmitter, ackEvent: string, ackEventPayload: T, wrapperFieldName: string, ackHandleWrapper?: PublishAcknowledgementHandleWrapper, compositionFunctor?: PublishAcknowledgementFunctor): void;
/** @internal */
export declare function queueAcknowledgeableEvent<T>(emitter: event.BufferedEventEmitter, ackEvent: string, ackEventPayload: T, wrapperFieldName: string, ackHandleWrapper?: PublishAcknowledgementHandleWrapper, compositionFunctor?: PublishAcknowledgementFunctor): void;
/**
 * Object that allows the holder to trigger the acknowledgement for an associated publish packet.
 */
export declare class PublishAcknowledgementHandle {
    private acknowledgementFunction?;
    constructor(acknowledgementFunction: PublishAcknowledgementFunctor);
    /**
     * trigger the acknowledgement for an associated Publish packet
     */
    invokeAcknowledgement(): void;
}