.js

const {INTERNAL_SERVER_ERROR, OK } = require('http-status-codes');

async function login(request, response, loginAction) {
  try {
    const actionResult = await loginAction(request.body);
    handleResponse(request, response, actionResult);
  } catch (e) {
    sendInternalServerError(response);
  }
}

function handleResponse(request, response, actionResult) {
  if (result(actionResult).hasStatusCode(OK)) {
    sendSuccessfulResponse(response, request, actionResult);
  } else {
    sendInternalServerError(response);
  }
}

function sendSuccessfulResponse(response, request, actionResult) {
  const headers = {'set-cookie': actionResult.headers['set-cookie']};
  const body = {};

  response.send(OK, body, headers);
}

function sendInternalServerError(response) {
  response.send(INTERNAL_SERVER_ERROR, { errorMessage: 'An unexpected error occurred.' });
}

function result(actionResult) {
  return {
    hasStatusCode: statusCode => {
      return actionResult.statusCode === statusCode;
    },
  };
}

module.exports = login;