const bodyParser = require('body-parser');
const awsServerlessExpressMiddleware = require('aws-serverless-express/middleware');
const AWS = require('aws-sdk');

const pipe = (...fns) => x => fns.reduce((y, f) => f(y), x);
const tapRoute = f => route => {
  route.use(f);
  return route;
};

const configureCors = route => {
  route.use(function(req, res, next) {
    res.header('Access-Control-Allow-Origin', '*');
    res.header(
      'Access-Control-Allow-Headers',
      'Origin, X-Requested-With, Content-Type, Accept'
    );
    next();
  });
  return route;
};

const injectUser = route => {
  route.use(async function(req, res, next) {
    try {
      const IDP_REGEX = /.*\/.*,(.*)\/(.*):CognitoSignIn:(.*)/;
      const authProvider =
        req.apiGateway.event.requestContext.identity
          .cognitoAuthenticationProvider;
      const [, , , userId] = authProvider.match(IDP_REGEX);

      const cognito = new AWS.CognitoIdentityServiceProvider();
      const listUsersResponse = await cognito
        .listUsers({
          UserPoolId: process.env.AUTH_LAMBDAUSERB2E6BC69_USERPOOLID,
          Filter: `sub = "${userId}"`,
          Limit: 1,
        })
        .promise();
      const user = listUsersResponse.Users[0];
      req.user = user;
      next();
    } catch (error) {
      console.log(error);
      next(error);
    }
  });
  return route;
};

const applyMiddleware = (route, ...middleware) =>
  pipe(
    tapRoute(bodyParser.json()),
    tapRoute(awsServerlessExpressMiddleware.eventContext()),
    configureCors,
    injectUser,
    ...middleware
  )(route);

module.exports = {
  applyMiddleware,
};