viewmodel-viewstate-actionstate.kt

val viewState = MutableLiveData<ViewState>()
val actionState = SingleLiveEvent<ActionState>() // each value emit only once

init {
    viewState.value = ViewState.Loading
    interactor.getProfile().let { getProfileState ->
        when (getProfileState) {
            is GetProfileInteractor.State.Success -> {
                // render updates on UI
                viewState.value = ViewState.ProfileLoaded(getProfileState.profile)
            }
            is GetProfileInteractor.State.Failure -> {
                viewState.value = ViewState.ProfileLoadFailure(getProfileState.errorMessage)
            }
            GetProfileInteractor.State.VerificationRequired -> {
                actionState.value = ActionState.NeedsVerification
            }
        }
    }
}

sealed class ViewState() {
    object Loading: ViewState()
    data class ProfileLoaded(val profile: Profile): ViewState()
    data class ProfileLoadFailure(val errorMessage: String): ViewState()
}

sealed class ActionState {
    object NeedsVerification : ActionState()
    object NeedsLogOut: ActionState()
}