user authentication

userAuth.js

const Auth = require("../lib/auth");
const multer = require("multer");
const upload = multer();
const asyncHandler = require("express-async-handler");

router.post("/signin", upload.none(), asyncHandler(async (req, res, next) => {
  const { email, plainTextPassword } = req.body;
  
  // get the hashed password associated to the email entered by user
  const query = `SELECT password FROM account WHERE email=($1)`;
  const values = [email];
  const { rows } = await db.query(query, values);

  const hashedPassword = rows[0].password;
  
  // (i love how they name the method to reflect its intention) 
  const isMatch = await Auth.comparePassword(plainTextPassword, hashedPassword);
  
  // if 'isMatch' is TRUE, means user entered the correct password, then let her in, and vice versa.
  if (!isMatch) {
    return next(
      createError(422, "Please enter a correct email and password")
    );
  }
  
  // we will use this flag to determine if a user is still logged in
  req.session.isLoggedIn = true;
  // we can also store additional user data 
  req.session.user = { user_id, ...userProfile };

  // up to you
  res.sendStatus(isMatch ? 200 : 401);
});