const express = require("express");
const router = express.Router();

const { from, EMPTY } = require("rxjs");
const { map, mergeMap } = require("rxjs/operators");

const bcrypt = require("bcrypt");
const saltRounds = 12;

const mongo = require("mongodb");
const MongoClient = mongo.MongoClient;
const url = "mongodb://localhost:27017";

const conn$ = from(MongoClient.connect(url));

// Mongo aux methods

const finduserByUsername = (collection, username) =>
  collection.find({ username }).toArray();

const insertUser = (collection, user) => collection.insertOne(user);

// Pipe methods

const retrieveUser = map(array => array[0]);

const detectNewUser = map(userData => {
  if (userData) {
    throw new Error("User already exists");
  } else {
    return EMPTY;
  }
});

const hashPassword = (password, saltRounds) =>
  mergeMap(_ => from(bcrypt.hash(password, saltRounds)));

const addPasswordHashToUser = userObj =>
  map(hash => ({ ...userObj, passwordHash: hash }));

const comparePassword = pwd =>
  mergeMap(user => from(bcrypt.compare(pwd, user.passwordHash)));

const addUser = collection =>
  mergeMap(user => from(insertUser(collection, user)));

// Client connection

conn$.subscribe(client => {
  const authstrongDB = client.db("authstrong");
  const usersColl = authstrongDB.collection("users");

  router.post("/authenticate", (req, res) => {
    const username = req.body.username || null;
    const password = req.body.password || null;

    const validUsername = username.match(/^[a-zA-Z]+$/);

    if (!!validUsername && password) {
      const auth$ = from(finduserByUsername(usersColl, username)).pipe(
        retrieveUser,
        comparePassword(password)
      );

      const next = authValid =>
        authValid
          ? res.status(200).send("Welcome to WestWorld.")
          : res.status(401).send("Wrong email or password.");

      const error = err => {
        // integrate a mechanism to log errors
        res.status(500).send("Wrong email or password.");
      };

      auth$.subscribe(next, error);
    } else {
      res.status(401).send("Wrong email or password.");
    }
  });

  router.post("/create", (req, res) => {
    const username = req.body.username || null;
    const password = req.body.password || null;
    const firstName = req.body.firstName || null;
    const lastName = req.body.lastName || null;
    const nickname = req.body.nickname || null;
    const status = req.body.status || null;

    const validUsername = username.match(/^[a-zA-Z]+$/);

    if (!!validUsername && password && firstName && lastName && status) {
      const createUser$ = from(usersColl.findOne({ username })).pipe(
        detectNewUser,
        hashPassword(password, saltRounds),
        addPasswordHashToUser({
          username,
          firstName,
          lastName,
          nickname,
          status
        }),
        addUser(usersColl)
      );

      const next = commandResult => res.status(200).send(`User created.`);

      const error = err => {
        console.log(err.message);
        res.status(500).send("Error: Invalid form data.");
      };

      createUser$.subscribe(next, error);
    } else {
      res.status(500).send("Error: Invalid form data.");
    }
  });
});

module.exports = router;