State.kt

import io.reactivex.Observable
import io.reactivex.subjects.BehaviorSubject

fun main() {

    View()
}

class View {

    init {

        val viewModel = ViewModel()
        val disposable = viewModel.getState().subscribe {
            println(it)
        }

        viewModel.login()
        viewModel.loading()
        viewModel.error()
        // viewModel.loading()

        disposable.dispose()

        viewModel.loading()
        println()

        viewModel.getState().subscribe {
            println(it)
        }
    }

}


class ViewModel {

    val behaviorSubject = BehaviorSubject.create<String>()
    val behaviorSubject2 = BehaviorSubject.create<String>()

    fun login() {
        behaviorSubject.onNext("Login")
    }

    fun loading() {
        behaviorSubject.onNext("Loading")
    }

    fun error() {
        behaviorSubject.onNext("Error")
    }

    fun getState(): Observable<String> {
        return behaviorSubject.scan { oldState, newState ->
            var state = newState

            if ((oldState == "Error") && (newState == "Loading")) {
                state = "Confused"
            }
            state
        }.replay(1).autoConnect(0)
    }
}