/* Basic example of saving cookie using axios in node.js and session's recreation after expiration.
 * We have to getting/saving cookie manually because WithCredential axios param use XHR and doesn't work in node.js
 * Also, this example supports parallel request and send only one create session request.
 * */

const BASE_URL = "https://google.com";

// Init instance of axios which works with BASE_URL
const axiosInstance = axios.create({ baseURL: BASE_URL });

const createSession = async () => {
  console.log("create session");
  const authParams = {
    username: "username",
    password: "password"
  };
  const resp = await axios.post(BASE_URL, authParams);
  const [cookie] = resp.headers["set-cookie"]; // getting cookie from request
  axiosInstance.defaults.headers.Cookie = cookie; // attaching cookie to axiosInstance for future requests
  return cookie; // return Promise<cookie> because func is async
};

let isGetActiveSessionRequest = false;
let requestQueue = [];

const callRequestsFromQueue = cookie => {
  requestQueue.forEach(sub => sub(cookie));
};
const addRequestToQueue = sub => {
  requestQueue.push(sub);
};
const clearQueue = () => {
  requestQueue = [];
};

// registering axios interceptor which handle response's errors
axiosInstance.interceptors.response.use(null, error => {
  console.error(error.message); //logging here

  const { response = {}, config: sourceConfig } = error;

  // checking if request failed cause Unauthorized
  if (response.status === 401) {
    // if this request is first we set isGetActiveSessionRequest flag to true and run createSession
    if (!isGetActiveSessionRequest) {
      isGetActiveSessionRequest = true;
      createSession().then(cookie => {
        // when createSession resolve with cookie value we run all request from queue with new cookie
        isGetActiveSessionRequest = false;
        callRequestsFromQueue(cookie);
        clearQueue(); // and clean queue
      }).catch(e => {
        isGetActiveSessionRequest = false; // Very important!
        console.error('Create session error %s', e.message);
        clearQueue();
      });
    }

    // and while isGetActiveSessionRequest equal true we create and return new promise
    const retryRequest = new Promise(resolve => {
      // we push new function to queue
      addRequestToQueue(cookie => {
        // function takes one param 'cookie'
        console.log("Retry with new session context %s request to %s", sourceConfig.method, sourceConfig.url);
        sourceConfig.headers.Cookie = cookie; // setting cookie to header
        resolve(axios(sourceConfig)); // and resolve promise with axios request by old config with cookie
        // we resolve exactly axios request - NOT axiosInstance's request because it could call recursion
      });
    });

    return retryRequest;
  } else {
    // if error is not related with Unauthorized we just reject promise
    return Promise.reject(error);
  }
});