MVP Pattern Implementation

mvp.kt

import java.util.Scanner

fun main() {
  val presenter: UserContract.UserPresenter = UserPresenterImpl()
  val view: UserContract.UserView = UserViewImpl(presenter)
  view.init()
}

interface UserContract {
  interface UserView {
    fun init()
    fun update(name: String, age: Int)
  }

  interface UserPresenter {
    fun init(view: UserView)
    fun setName(name: String)
    fun setAge(age: Int)
  }

  data class UserModel(
    val name: String,
    val age: Int,
  )
}

class UserViewImpl(
  private val presenter: UserContract.UserPresenter
) : UserContract.UserView {

  override fun init() {
    presenter.init(this)
    setUpform()
  }

  override fun update(name: String, age: Int) {
    println("Name: $name | age: $age")
  }

  private fun setUpform() {
    val scanner = Scanner(System.`in`)
    val name = scanner.nextLine()
    presenter.setName(name)
    val age = scanner.nextInt()
    presenter.setAge(age)
  }
}

class UserPresenterImpl : UserContract.UserPresenter {

  lateinit var view: UserContract.UserView

  private var user = UserContract.UserModel(
    name = "",
    age = 0
  )

  override fun init(view: UserContract.UserView) {
    this.view = view
    this.view.update(user.name, user.age)
  }

  override fun setName(name: String) {
    user = user.copy(name = name)
    view.update(user.name, user.age)
  }

  override fun setAge(age: Int) {
    user = user.copy(age = age)
    view.update(user.name, user.age)
  }
}