/**
 * -------------------------------------------------------------------------------------------
 * Copyright (c) Microsoft Corporation.  All Rights Reserved.  Licensed under the MIT License.
 * See License in the project root for license information.
 * -------------------------------------------------------------------------------------------
 */
/**
 * @module RetryHandler
 */
import { Context } from "../IContext";
import { Middleware } from "./IMiddleware";
import { RetryHandlerOptions } from "./options/RetryHandlerOptions";
/**
 * @class
 * @implements Middleware
 * Class for RetryHandler
 */
export declare class RetryHandler implements Middleware {
    /**
     * @private
     * @static
     * A list of status codes that needs to be retried
     */
    private static RETRY_STATUS_CODES;
    /**
     * @private
     * @static
     * A member holding the name of retry attempt header
     */
    private static RETRY_ATTEMPT_HEADER;
    /**
     * @private
     * @static
     * A member holding the name of retry after header
     */
    private static RETRY_AFTER_HEADER;
    /**
     * @private
     * A member to hold next middleware in the middleware chain
     */
    private nextMiddleware;
    /**
     * @private
     * A member holding the retry handler options
     */
    private options;
    /**
     * @public
     * @constructor
     * To create an instance of RetryHandler
     * @param {RetryHandlerOptions} [options = new RetryHandlerOptions()] - The retry handler options value
     * @returns An instance of RetryHandler
     */
    constructor(options?: RetryHandlerOptions);
    /**
     *
     * @private
     * To check whether the response has the retry status code
     * @param {Response} response - The response object
     * @returns Whether the response has retry status code or not
     */
    private isRetry;
    /**
     * @private
     * To check whether the payload is buffered or not
     * @param {RequestInfo} request - The url string or the request object value
     * @param {FetchOptions} options - The options of a request
     * @returns Whether the payload is buffered or not
     */
    private isBuffered;
    /**
     * @private
     * To get the delay for a retry
     * @param {Response} response - The response object
     * @param {number} retryAttempts - The current attempt count
     * @param {number} delay - The delay value in seconds
     * @returns A delay for a retry
     */
    private getDelay;
    /**
     * @private
     * To get an exponential back off value
     * @param {number} attempts - The current attempt count
     * @returns An exponential back off value
     */
    private getExponentialBackOffTime;
    /**
     * @private
     * @async
     * To add delay for the execution
     * @param {number} delaySeconds - The delay value in seconds
     * @returns Nothing
     */
    private sleep;
    private getOptions;
    /**
     * @private
     * @async
     * To execute the middleware with retries
     * @param {Context} context - The context object
     * @param {number} retryAttempts - The current attempt count
     * @param {RetryHandlerOptions} options - The retry middleware options instance
     * @returns A Promise that resolves to nothing
     */
    private executeWithRetry;
    /**
     * @public
     * @async
     * To execute the current middleware
     * @param {Context} context - The context object of the request
     * @returns A Promise that resolves to nothing
     */
    execute(context: Context): Promise<void>;
    /**
     * @public
     * To set the next middleware in the chain
     * @param {Middleware} next - The middleware instance
     * @returns Nothing
     */
    setNext(next: Middleware): void;
}