LoginArchPresenter.kt

  override fun onInit() {
      viewModel?.readyToLogin?.set(false)
      viewModel?.onClickLogin?.set(View.OnClickListener { _ ->
          view.performLogin(viewModel?.email?.get() + " " + viewModel?.password?.get())
          viewModel?.email?.set("")
          viewModel?.password?.set("")
      })
  }

  override fun setReadyToClick(isReady: Boolean) {
      viewModel?.readyToLogin?.set(isReady)
  }

  override fun onEmailUpdate(string: String) {
      viewModel?.email?.set(string)
      checkIsReadyToSignIn()
  }

  override fun onPasswordUpdate(string: String) {
      viewModel?.password?.set(string)
      checkIsReadyToSignIn()
  }

  private fun checkIsReadyToSignIn() {
      val notEmptyStrings = TextHelper.isNotEmptyStrings(viewModel?.email?.get(),
              viewModel?.password?.get())
      setReadyToClick(notEmptyStrings)
  }