Android Clean

Greeting.kt

interface View {
    fun setGreeting(greeting: String)
}

interface Presenter {
    fun onDestroy()
    fun getGreeting()
}

interface Interactor {
    suspend fun provideGreetingData(): GreetingData
}

interface Repository {
    suspend fun getPerson(): Person
}

class Person(var firstName: String, var lastName: String) //entity
class GreetingData(var greeting: String, var subject: String) //transport structure

class GreetingPresenter(var view: View?, var interactor: Interactor) : Presenter {
    override fun onDestroy() {
        view = null
    }

    override fun getGreeting() {
        view?.let{ v ->
            async(UI) {
                val greetingData: GreetingData = asyncGetGreetingData().await()
                val greeting = "${greetingData.greeting} ${greetingData.subject}"
                v.setGreeting(greeting)
            }
        }
    }

    private fun asyncGetGreetingData(): Deferred<GreetingData> = async(CommonPool) { interactor.provideGreetingData() }
}

class GreetingInteractor(val repository: GreetingRepository) : Interactor {
    override suspend fun provideGreetingData() : GreetingData {
        var person: Person = asyncGetPerson().await()
        var subject = "${person.firstName} ${person.lastName}"
        return GreetingData("Hello", subject)
    }

    private fun asyncGetPerson(): Deferred<Person> = async(CommonPool) { repository.getPerson() }
}

class GreetingRepository : Repository {
    override suspend fun getPerson(): Person {
        return Person("Adrian", "Catalan")
    }
}

class GreetingComponents(view: View) {
    var repository: GreetingRepository = GreetingRepository()
    var interactor: GreetingInteractor = GreetingInteractor(repository)
    var presenter: GreetingPresenter = GreetingPresenter(view, interactor)
}

class GreetingActivity : AppCompatActivity(), View {
    var components: GreetingComponents = GreetingComponents(this)
    var presenter: Presenter = components.presenter

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_greeting)

        btnShowGreet.setOnClickListener {
            presenter.getGreeting()
        }
    }

    override fun onDestroy() {
        presenter.onDestroy()
        super.onDestroy()
    }

    override fun setGreeting(greeting: String) {
        txtGreet.text = greeting
    }

}