// 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 { WebResource } from "../webResource";
import { BaseRequestPolicy, RequestPolicy, RequestPolicyFactory, RequestPolicyOptions } from "./requestPolicy";

export function rpRegistrationPolicy(retryTimeout = 30): RequestPolicyFactory {
  return {
    create: (nextPolicy: RequestPolicy, options: RequestPolicyOptions) => {
      return new RPRegistrationPolicy(nextPolicy, options, retryTimeout);
    }
  };
}

export class RPRegistrationPolicy extends BaseRequestPolicy {
  constructor(nextPolicy: RequestPolicy, options: RequestPolicyOptions, readonly _retryTimeout = 30) {
    super(nextPolicy, options);
  }

  public sendRequest(request: WebResource): Promise<HttpOperationResponse> {
    return this._nextPolicy.sendRequest(request.clone())
      .then(response => registerIfNeeded(this, request, response));
  }
}


function registerIfNeeded(policy: RPRegistrationPolicy, request: WebResource, response: HttpOperationResponse): Promise<HttpOperationResponse> {
  if (response.status === 409) {
    const rpName = checkRPNotRegisteredError(response.bodyAsText as string);
    if (rpName) {
      const urlPrefix = extractSubscriptionUrl(request.url);
      return registerRP(policy, urlPrefix, rpName, request)
        // Autoregistration of ${provider} failed for some reason. We will not return this error
        // instead will return the initial response with 409 status code back to the user.
        // do nothing here as we are returning the original response at the end of this method.
        .catch(() => false)
        .then(registrationStatus => {
          if (registrationStatus) {
            // Retry the original request. We have to change the x-ms-client-request-id
            // otherwise Azure endpoint will return the initial 409 (cached) response.
            request.headers.set("x-ms-client-request-id", utils.generateUuid());
            return policy._nextPolicy.sendRequest(request.clone());
          }
          return response;
        });
    }
  }

  return Promise.resolve(response);
}

/**
 * Reuses the headers of the original request and url (if specified).
 * @param {WebResource} originalRequest The original request
 * @param {boolean} reuseUrlToo Should the url from the original request be reused as well. Default false.
 * @returns {object} A new request object with desired headers.
 */
function getRequestEssentials(originalRequest: WebResource, reuseUrlToo = false): WebResource {
  const reqOptions: WebResource = originalRequest.clone();
  if (reuseUrlToo) {
    reqOptions.url = originalRequest.url;
  }

  // We have to change the x-ms-client-request-id otherwise Azure endpoint
  // will return the initial 409 (cached) response.
  reqOptions.headers.set("x-ms-client-request-id", utils.generateUuid());

  // Set content-type to application/json
  reqOptions.headers.set("Content-Type", "application/json; charset=utf-8");

  return reqOptions;
}

/**
 * Validates the error code and message associated with 409 response status code. If it matches to that of
 * RP not registered then it returns the name of the RP else returns undefined.
 * @param {string} body The response body received after making the original request.
 * @returns {string} The name of the RP if condition is satisfied else undefined.
 */
function checkRPNotRegisteredError(body: string): string {
  let result, responseBody;
  if (body) {
    try {
      responseBody = JSON.parse(body);
    } catch (err) {
      // do nothing;
    }
    if (responseBody && responseBody.error && responseBody.error.message &&
      responseBody.error.code && responseBody.error.code === "MissingSubscriptionRegistration") {
      const matchRes = responseBody.error.message.match(/.*'(.*)'/i);
      if (matchRes) {
        result = matchRes.pop();
      }
    }
  }
  return result;
}

/**
 * Extracts the first part of the URL, just after subscription:
 * https://management.azure.com/subscriptions/00000000-0000-0000-0000-000000000000/
 * @param {string} url The original request url
 * @returns {string} The url prefix as explained above.
 */
function extractSubscriptionUrl(url: string): string {
  let result;
  const matchRes = url.match(/.*\/subscriptions\/[a-f0-9-]+\//ig);
  if (matchRes && matchRes[0]) {
    result = matchRes[0];
  } else {
    throw new Error(`Unable to extract subscriptionId from the given url - ${url}.`);
  }
  return result;
}

/**
 * Registers the given provider.
 * @param {RPRegistrationPolicy} policy The RPRegistrationPolicy this function is being called against.
 * @param {string} urlPrefix https://management.azure.com/subscriptions/00000000-0000-0000-0000-000000000000/
 * @param {string} provider The provider name to be registered.
 * @param {WebResource} originalRequest The original request sent by the user that returned a 409 response
 * with a message that the provider is not registered.
 * @param {registrationCallback} callback The callback that handles the RP registration
 */
function registerRP(policy: RPRegistrationPolicy, urlPrefix: string, provider: string, originalRequest: WebResource): Promise<boolean> {
  const postUrl = `${urlPrefix}providers/${provider}/register?api-version=2016-02-01`;
  const getUrl = `${urlPrefix}providers/${provider}?api-version=2016-02-01`;
  const reqOptions = getRequestEssentials(originalRequest);
  reqOptions.method = "POST";
  reqOptions.url = postUrl;

  return policy._nextPolicy.sendRequest(reqOptions)
    .then(response => {
      if (response.status !== 200) {
        throw new Error(`Autoregistration of ${provider} failed. Please try registering manually.`);
      }
      return getRegistrationStatus(policy, getUrl, originalRequest);
    });
}

/**
 * Polls the registration status of the provider that was registered. Polling happens at an interval of 30 seconds.
 * Polling will happen till the registrationState property of the response body is "Registered".
 * @param {RPRegistrationPolicy} policy The RPRegistrationPolicy this function is being called against.
 * @param {string} url The request url for polling
 * @param {WebResource} originalRequest The original request sent by the user that returned a 409 response
 * with a message that the provider is not registered.
 * @returns {Promise<boolean>} True if RP Registration is successful.
 */
function getRegistrationStatus(policy: RPRegistrationPolicy, url: string, originalRequest: WebResource): Promise<boolean> {
  const reqOptions: any = getRequestEssentials(originalRequest);
  reqOptions.url = url;
  reqOptions.method = "GET";

  return policy._nextPolicy.sendRequest(reqOptions).then(res => {
    const obj = (res.parsedBody as any);
    if (res.parsedBody && obj.registrationState && obj.registrationState === "Registered") {
      return true;
    } else {
      return utils.delay(policy._retryTimeout * 1000).then(() => getRegistrationStatus(policy, url, originalRequest));
    }
  });
}