case class

// case classes
// 一种特别的类，　
// 默认不可变／可以通过模式匹配分解／关于比较／实例起来很简洁＝＞不需要使用ｎｅｗ
abstract class Notification
case class Email(sourceEmail: String,  title: String, body: String) extends Notification
case class SMS(sourceNumber: String, var message: String) extends Notification
case class VoiceRecording(contactName: String, link: String) extends Notification

// 不需要使用ｎｅｗ　实例化时很简洁
val emailFromJohn = Email("john.doe@mail.com", "Greetings From John!", "Hello World!")
val smsFromJohn = SMS("john.doe@mail.com", "Greetings From John!")
val title = emailFromJohn.title// 默认是公有的
println(title)

//　但是不可变的　因此不能重写＜除非开始的时候申明为ｖａｒ　但不鼓励这样　＞
emailFromJohn.title = "Goodbye From John!" // This is a compilation
smsFromJohn.message = "ok"

// 但是可以借助copy方法　，　拷贝的过程中，　改写原来的
val editedEmail = emailFromJohn.copy(title = "I am learning Scala!", body = "It's so cool!")
println(emailFromJohn) // prints "Email(john.doe@mail.com,Greetings From John!,Hello World!)"
println(editedEmail) // prints "Email(john.doe@mail.com,I am learning Scala,It's so cool!)"


// 比较相等　是比较每个成员的值
//　case类一定会实现　＝＝　和　tostring
val firstSms = SMS("12345", "Hello!")
val secondSms = SMS("12345", "Hello!")
if (firstSms == secondSms) {
  println("They are equal!")
}
println("SMS is: " + firstSms)



// 还可以使用模式匹配　这样表达更简洁
def showNotification(notification: Notification): String = {
  notification match {
    case Email(email, title, _) =>
      "You got an email from " + email + " with title: " + title
    case SMS(number, message) =>
      "You got an SMS from " + number + "! Message: " + message
    case VoiceRecording(name, link) =>
      "you received a Voice Recording from " + name + "! Click the link to hear it: " + link
  }
}
val someSms = SMS("12345", "Are you there?")
val someVoiceRecording = VoiceRecording("Tom", "voicerecording.org/id/123")
println(showNotification(someSms))
println(showNotification(someVoiceRecording))
// prints:
// You got an SMS from 12345! Message: Are you there?
// you received a Voice Recording from Tom! Click the link to hear it: voicerecording.org/id/123


def showNotificationSpecial(notification: Notification, specialEmail: String, specialNumber: String): String = {
  notification match {
    case Email(email, _, _) if email == specialEmail =>
      "You got an email from special someone!"
    case SMS(number, _) if number == specialNumber =>
      "You got an SMS from special someone!"
    case other =>
      showNotification(other) // nothing special, delegate to our original showNotification function
  }
}
val SPECIAL_NUMBER = "55555"
val SPECIAL_EMAIL = "jane@mail.com"
val someSms2 = SMS("12345", "Are you there?")
val someVoiceRecording2 = VoiceRecording("Tom", "voicerecording.org/id/123")
val specialEmail = Email("jane@mail.com", "Drinks tonight?", "I'm free after 5!")
val specialSms = SMS("55555", "I'm here! Where are you?")
println(showNotificationSpecial(someSms2, SPECIAL_EMAIL, SPECIAL_NUMBER))
println(showNotificationSpecial(someVoiceRecording2, SPECIAL_EMAIL, SPECIAL_NUMBER))
println(showNotificationSpecial(specialEmail, SPECIAL_EMAIL, SPECIAL_NUMBER))
println(showNotificationSpecial(specialSms, SPECIAL_EMAIL, SPECIAL_NUMBER))
// prints:
// You got an SMS from 12345! Message: Are you there?
// you received a Voice Recording from Tom! Click the link to hear it: voicerecording.org/id/123
// You got an email from special someone!
// You got an SMS from special someone!