class RepositoryImpl(private val auth: FirebaseAuth) : Repository {

	override fun signIn(email: String,password: String) {
		auth.signWithInEmailAndPassword(email, password)
	}
}

// domain
interface AuthRepository {
	 fun signIn()
}

class MyApplication : Application() {
	lateinit var viewModel: MainViewModel

	override fun onCreate(){
		val auth = FirebaseAuth.getInstance()
		val repository = RepositoryImpl(auth)
		val interactor = InteractorImpl(repository)
	  	viewModel = MainViewModel(interactor)
	}
}

class MainActivity {

	override fun onCreate() {
		val myApplication = application as MyApplication

		val viewModel = myApplication.viewModel
	}
}