/// <reference types="node" />
/**
 * @packageDocumentation
 * @module mqtt_shared
 */
import * as mqtt_shared from "../common/mqtt_shared";
import * as mqtt5 from "../common/mqtt5";
/**
 * 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 interface TopicProperties {
    isValid: boolean;
    isShared: boolean;
    hasWildcard: boolean;
}
/** @internal */
export declare function computeTopicProperties(topic: string, isFilter: boolean): TopicProperties;
/** @internal */
export declare function isValidTopicFilter(topicFilter: any): boolean;
/** @internal */
export declare function isValidTopic(topic: any): boolean;
/** @internal */
export interface ReconnectDelayContext {
    retryJitterMode?: mqtt5.RetryJitterType;
    minReconnectDelayMs?: number;
    maxReconnectDelayMs?: number;
    lastReconnectDelay?: number;
    connectionFailureCount: number;
}
/**
 * Computes the next reconnect delay based on the Jitter/Retry configuration.
 * Implements jitter calculations in https://aws.amazon.com/blogs/architecture/exponential-backoff-and-jitter/
 * @internal
 */
export declare function calculateNextReconnectDelay(context: ReconnectDelayContext): number;
export declare function buildFinalUsernameFromMetrics(metrics: mqtt_shared.AWSIoTMetrics, username?: string): string;