// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License. See License.txt in the project root for license information.

import { HttpOperationResponse } from "../httpOperationResponse";
import * as utils from "../util/utils";
import { WebResourceLike } from "../webResource";
import {
  BaseRequestPolicy,
  RequestPolicy,
  RequestPolicyFactory,
  RequestPolicyOptionsLike,
} from "./requestPolicy";

export interface RetryData {
  retryCount: number;
  retryInterval: number;
  error?: RetryError;
}

export interface RetryError extends Error {
  message: string;
  code?: string;
  innerError?: RetryError;
}

export function systemErrorRetryPolicy(
  retryCount?: number,
  retryInterval?: number,
  minRetryInterval?: number,
  maxRetryInterval?: number
): RequestPolicyFactory {
  return {
    create: (nextPolicy: RequestPolicy, options: RequestPolicyOptionsLike) => {
      return new SystemErrorRetryPolicy(
        nextPolicy,
        options,
        retryCount,
        retryInterval,
        minRetryInterval,
        maxRetryInterval
      );
    },
  };
}

/**
 * @class
 * Instantiates a new "ExponentialRetryPolicyFilter" instance.
 *
 * @constructor
 * @param {number} retryCount        The client retry count.
 * @param {number} retryInterval     The client retry interval, in milliseconds.
 * @param {number} minRetryInterval  The minimum retry interval, in milliseconds.
 * @param {number} maxRetryInterval  The maximum retry interval, in milliseconds.
 */
export class SystemErrorRetryPolicy extends BaseRequestPolicy {
  retryCount: number;
  retryInterval: number;
  minRetryInterval: number;
  maxRetryInterval: number;
  DEFAULT_CLIENT_RETRY_INTERVAL = 1000 * 30;
  DEFAULT_CLIENT_RETRY_COUNT = 3;
  DEFAULT_CLIENT_MAX_RETRY_INTERVAL = 1000 * 90;
  DEFAULT_CLIENT_MIN_RETRY_INTERVAL = 1000 * 3;

  constructor(
    nextPolicy: RequestPolicy,
    options: RequestPolicyOptionsLike,
    retryCount?: number,
    retryInterval?: number,
    minRetryInterval?: number,
    maxRetryInterval?: number
  ) {
    super(nextPolicy, options);
    this.retryCount = typeof retryCount === "number" ? retryCount : this.DEFAULT_CLIENT_RETRY_COUNT;
    this.retryInterval =
      typeof retryInterval === "number" ? retryInterval : this.DEFAULT_CLIENT_RETRY_INTERVAL;
    this.minRetryInterval =
      typeof minRetryInterval === "number"
        ? minRetryInterval
        : this.DEFAULT_CLIENT_MIN_RETRY_INTERVAL;
    this.maxRetryInterval =
      typeof maxRetryInterval === "number"
        ? maxRetryInterval
        : this.DEFAULT_CLIENT_MAX_RETRY_INTERVAL;
  }

  public sendRequest(request: WebResourceLike): Promise<HttpOperationResponse> {
    return this._nextPolicy
      .sendRequest(request.clone())
      .catch((error) => retry(this, request, error.response, error));
  }
}

/**
 * Determines if the operation should be retried and how long to wait until the next retry.
 *
 * @param {number} statusCode The HTTP status code.
 * @param {RetryData} retryData  The retry data.
 * @return {boolean} True if the operation qualifies for a retry; false otherwise.
 */
function shouldRetry(policy: SystemErrorRetryPolicy, retryData: RetryData): boolean {
  let currentCount;
  if (!retryData) {
    throw new Error("retryData for the SystemErrorRetryPolicyFilter cannot be null.");
  } else {
    currentCount = retryData && retryData.retryCount;
  }
  return currentCount < policy.retryCount;
}

/**
 * Updates the retry data for the next attempt.
 *
 * @param {RetryData} retryData  The retry data.
 * @param {object} err        The operation"s error, if any.
 */
function updateRetryData(
  policy: SystemErrorRetryPolicy,
  retryData?: RetryData,
  err?: RetryError
): RetryData {
  if (!retryData) {
    retryData = {
      retryCount: 0,
      retryInterval: 0,
    };
  }

  if (err) {
    if (retryData.error) {
      err.innerError = retryData.error;
    }

    retryData.error = err;
  }

  // Adjust retry count
  retryData.retryCount++;

  // Adjust retry interval
  let incrementDelta = Math.pow(2, retryData.retryCount) - 1;
  const boundedRandDelta =
    policy.retryInterval * 0.8 + Math.floor(Math.random() * (policy.retryInterval * 0.4));
  incrementDelta *= boundedRandDelta;

  retryData.retryInterval = Math.min(
    policy.minRetryInterval + incrementDelta,
    policy.maxRetryInterval
  );

  return retryData;
}

async function retry(
  policy: SystemErrorRetryPolicy,
  request: WebResourceLike,
  operationResponse: HttpOperationResponse,
  err?: RetryError,
  retryData?: RetryData
): Promise<HttpOperationResponse> {
  retryData = updateRetryData(policy, retryData, err);
  if (
    err &&
    err.code &&
    shouldRetry(policy, retryData) &&
    (err.code === "ETIMEDOUT" ||
      err.code === "ESOCKETTIMEDOUT" ||
      err.code === "ECONNREFUSED" ||
      err.code === "ECONNRESET" ||
      err.code === "ENOENT")
  ) {
    // If previous operation ended with an error and the policy allows a retry, do that
    try {
      await utils.delay(retryData.retryInterval);
      return policy._nextPolicy.sendRequest(request.clone());
    } catch (error) {
      return retry(policy, request, operationResponse, error, retryData);
    }
  } else {
    if (err) {
      // If the operation failed in the end, return all errors instead of just the last one
      return Promise.reject(retryData.error);
    }
    return operationResponse;
  }
}