Attention.md

Two-Factor Authentication using Future[T] (Scala)

• Convert imperative scala code to functional-style using Future
• Refer to Authentication.scala for this refactoring.
• You are not allowed to change the signature of loginChores, feel free to do whatever you want with other functions.

Authentication.scala

case class User(login: String, name: String)

def login(login: String, pwd: String): User = {
  println(s"Inside system login: $login")
  Thread.sleep(500)
  if (login == "" || login == null || login.contains("@gmail")) throw new Exception(s"invalid id $login")
  else if (pwd == "" || pwd == null) throw new Exception("invalid password")
  else User(login, "Dhaval")
}

def gmailLogin(login: String, pwd: String): User = {
  println(s"Inside gmail login: $login")
  Thread.sleep(1000)
  if (login.contains("@gmail")) User(login, "Dhaval")
  else if (pwd == "" || pwd == null) throw new Exception("invalid password")
  else throw new Exception("Not a Gmail Id!") 
}

def twoFactor(user: User, pwd: Long): User = {
  println(s"Inside twoFactor: ${user.login}")
  Thread.sleep(500)
  if (pwd >= 100000 && pwd <= 999999) user
  else throw new Exception("twoFactor: Incorrect key")
}

import java.net.URL
def redirect(target: URL) = println(s"Going to => $target")

def loginChores(userid: String, pwd: String, twoFactorPwd: Long): Unit = {
  val dashboard = new URL("https://dashboard")
  val loginPage = new URL("https://login")
  var user: User = null
  try {
    user = login(userid, pwd)
  } catch {
    case e: Exception => 
      println("system login failed = " + e.getMessage)
      try {
        user = gmailLogin(userid, pwd)
      } catch {
        case eg: Exception =>
          println("gmail login failed = " + eg.getMessage)
          redirect(loginPage)
          return
      }
  }
  var target: URL = null
  try {
    twoFactor(user, twoFactorPwd)
    target = dashboard
  } catch {
    case e: Exception => 
      println("Two factor auth failed = " + e.getMessage)
      target = loginPage
  }
  redirect(target)
}

// System Login Path success
loginChores("[email protected]", "test", 123456)
// System Login Path 2-factor fails
loginChores("[email protected]", "test", 12345)

// Gmail Login Path success
loginChores("[email protected]", "test", 123456)
// Gmail Login Path 2-factor fails
loginChores("[email protected]", "test", 12345)

// System Login and Gmail Login fails
loginChores("", "test", 123456)