Scala - Extractor and Pattern Matching.scala

trait User {
  def name: String
}

//class FreeUser(name: String, upgradeProbality: Double) extends User
//class PremiumUser(name: String, loaltyPoint: Double) extends User

//val user1 = new FreeUser("John", 0.75)
//println(user1.name)  doesn't work

class FreeUser(val name: String, val upgradeProbality: Double) extends User

class PremiumUser(val name: String, val loaltyPoint: Double) extends User

//val user1 = new FreeUser("John", 0.75)
//println(s"Hello ${user1.name}")

// pattern matching

object FreeUser {
  def unapply(user: FreeUser): Option[(String, Double)] = Some((user.name, user.upgradeProbality))
}

object PremiumUser {
  def unapply(user: PremiumUser): Option[(String, Double)] =
    Some(user.name, user.loaltyPoint)
}

val user1: User = new FreeUser("John", 0.75)
val user2: User = new PremiumUser("Rebacca", 120)

def greetUser(user: User): Unit = user match {
    case FreeUser(name, _) => println(s"Hello $name")
    case PremiumUser(name, _) => println(s"Hello $name, what can I do for you?")
  }

greetUser(user1)
greetUser(user2)

List(user1,user2) foreach greetUser

// Boolean extractor

def sendUpgradeSpam(user: FreeUser) = {
  val message = s"Hello  ${user.name}, congratulations!! You're eleigible for " +
    s"our premium services. For more information, pleaes visit our site: http://play/premium"
  println(message)
}

def isUpgradeEligible(user: FreeUser): Boolean = {
  if (user.upgradeProbality > 0.6) true else false
}

// using a function

def spam(user: FreeUser) = {
  if (isUpgradeEligible(user)) println("Yes, Send him an email")
  else println("No, Don't spam him")
}
spam(new FreeUser("Joe", 0.4))





// object and pattern matching
object UpgradeEligible {
  def unapply(user: FreeUser): Boolean =
    if (user.upgradeProbality > 0.6) true else false
}

val user3 = new FreeUser("Joe", 0.4)

/*
user3 match {
  case UpgradeEligible() => println("Yes, Send him an email") // if true
  case _ => println("No, Don't spam him") // if false
}
*/


def spamEligibleUsers(user: User): Unit = user match {
  case freeUser @ UpgradeEligible() => sendUpgradeSpam(freeUser)
  case _ => // do nothing
}

spamEligibleUsers(user1)


def makeArray[T: ClassTag](elements: T*) = Array[T](elements: _*)

makeArray(1, 2 ,3, 4)