Reactive Activity Lifecycles

ActivityLifecycles.kt

package com.vinaysshenoy.android.arch

import com.vinaysshenoy.android.arch.Event.DESTROY
import com.vinaysshenoy.android.arch.Event.PAUSE
import com.vinaysshenoy.android.arch.Event.RESUME
import com.vinaysshenoy.android.arch.Event.START
import com.vinaysshenoy.android.arch.Event.STOP
import io.reactivex.Observable
import io.reactivex.disposables.CompositeDisposable
import io.reactivex.subjects.PublishSubject

/**
 * Created by vinaysshenoy on 22/11/17.
 */

sealed class Event

object Start : Event()
object Resume : Event()
object Pause : Event()
object Stop : Event()
object Destroy : Event()
data class ActivityResult(val requestCode: Int, val resultCode: Int, val data: Intent?) : Event()

class RxActivityLifecycle {

  private val disposables = CompositeDisposable()

  private val eventPublisher = PublishSubject.create<Event>()

  val starts: Observable<Start>
    get() = eventPublisher
        .filter { it is Start }
        .cast(Start::class.java)
        .doOnSubscribe { disposables.add(it) }

  val resumes: Observable<Resume>
    get() = eventPublisher
        .filter { it is Resume }
        .cast(Resume::class.java)
        .doOnSubscribe { disposables.add(it) }

  val pauses: Observable<Pause>
    get() = eventPublisher
        .filter { it is Pause }
        .cast(Pause::class.java)
        .doOnSubscribe { disposables.add(it) }

  val stops: Observable<Stop>
    get() = eventPublisher
        .filter { it is Stop }
        .cast(Stop::class.java)
        .doOnSubscribe { disposables.add(it) }

  val destroy: Observable<Destroy>
    get() = eventPublisher
        .filter { it is Destroy }
        .cast(Destroy::class.java)
        .doOnSubscribe { disposables.add(it) }

  val activityResults: Observable<ActivityResult>
    get() = eventPublisher
        .filter { it is ActivityResult }
        .cast(ActivityResult::class.java)
        .doOnSubscribe { disposables.add(it) }

  val events: Observable<Event>
    get() = eventPublisher
        .doOnSubscribe { disposables.add(it) }

  fun onActivityStart() {
    eventPublisher.onNext(Start)
  }

  fun onActivityResume() {
    eventPublisher.onNext(Resume)
  }

  fun onActivityPause() {
    eventPublisher.onNext(Pause)
  }

  fun onActivityStop() {
    eventPublisher.onNext(Stop)
  }

  fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    eventPublisher.onNext(ActivityResult(requestCode, resultCode, data))
  }

  fun onActivityDestroy() {
    eventPublisher.onNext(Destroy)
    disposables.dispose()
  }