/**
 * Copyright (C) 2009-2016 Lightbend Inc. <http://www.lightbend.com>
 */
package akka.stream.impl.fusing

import akka.stream.Attributes
import akka.stream.impl.fusing.GraphStages.SimpleLinearGraphStage
import akka.stream.stage._
import akka.testkit.AkkaSpec
import akka.stream.testkit.Utils.TE

import scala.concurrent.duration._

class LifecycleInterpreterSpec extends AkkaSpec with GraphInterpreterSpecKit {
  import akka.stream.Supervision._

  "Interpreter" must {

    "call preStart in order on stages" in new OneBoundedSetup[String](
      PreStartAndPostStopIdentity(onStart = () ⇒ testActor ! "start-a"),
      PreStartAndPostStopIdentity(onStart = () ⇒ testActor ! "start-b"),
      PreStartAndPostStopIdentity(onStart = () ⇒ testActor ! "start-c")) {
      expectMsg("start-a")
      expectMsg("start-b")
      expectMsg("start-c")
      expectNoMsg(300.millis)
      upstream.onComplete()
    }

    "call postStop in order on stages - when upstream completes" in new OneBoundedSetup[String](
      PreStartAndPostStopIdentity(onUpstreamCompleted = () ⇒ testActor ! "complete-a", onStop = () ⇒ testActor ! "stop-a"),
      PreStartAndPostStopIdentity(onUpstreamCompleted = () ⇒ testActor ! "complete-b", onStop = () ⇒ testActor ! "stop-b"),
      PreStartAndPostStopIdentity(onUpstreamCompleted = () ⇒ testActor ! "complete-c", onStop = () ⇒ testActor ! "stop-c")) {
      upstream.onComplete()
      expectMsg("complete-a")
      expectMsg("stop-a")
      expectMsg("complete-b")
      expectMsg("stop-b")
      expectMsg("complete-c")
      expectMsg("stop-c")
      expectNoMsg(300.millis)
    }

    "call postStop in order on stages - when upstream onErrors" in new OneBoundedSetup[String](
      PreStartAndPostStopIdentity(
        onUpstreamFailed = ex ⇒ testActor ! ex.getMessage,
        onStop = () ⇒ testActor ! "stop-c")) {
      val msg = "Boom! Boom! Boom!"
      upstream.onError(TE(msg))
      expectMsg(msg)
      expectMsg("stop-c")
      expectNoMsg(300.millis)
    }

    "call postStop in order on stages - when downstream cancels" in new OneBoundedSetup[String](
      PreStartAndPostStopIdentity(onStop = () ⇒ testActor ! "stop-a"),
      PreStartAndPostStopIdentity(onStop = () ⇒ testActor ! "stop-b"),
      PreStartAndPostStopIdentity(onStop = () ⇒ testActor ! "stop-c")) {
      downstream.cancel()
      expectMsg("stop-c")
      expectMsg("stop-b")
      expectMsg("stop-a")
      expectNoMsg(300.millis)
    }

    "call preStart before postStop" in new OneBoundedSetup[String](
      PreStartAndPostStopIdentity(onStart = () ⇒ testActor ! "start-a", onStop = () ⇒ testActor ! "stop-a")) {
      expectMsg("start-a")
      expectNoMsg(300.millis)
      upstream.onComplete()
      expectMsg("stop-a")
      expectNoMsg(300.millis)
    }

    "onError when preStart fails" in new OneBoundedSetup[String](
      PreStartFailer(() ⇒ throw TE("Boom!"))) {
      lastEvents() should ===(Set(Cancel, OnError(TE("Boom!"))))
    }

    "not blow up when postStop fails" in new OneBoundedSetup[String](
      PostStopFailer(() ⇒ throw TE("Boom!"))) {
      upstream.onComplete()
      lastEvents() should ===(Set(OnComplete))
    }

    "onError when preStart fails with stages after" in new OneBoundedSetup[String](
      Map((x: Int) ⇒ x, stoppingDecider).toGS,
      PreStartFailer(() ⇒ throw TE("Boom!")),
      Map((x: Int) ⇒ x, stoppingDecider).toGS) {
      lastEvents() should ===(Set(Cancel, OnError(TE("Boom!"))))
    }

    "continue with stream shutdown when postStop fails" in new OneBoundedSetup[String](
      PostStopFailer(() ⇒ throw TE("Boom!"))) {
      lastEvents() should ===(Set())

      upstream.onComplete()
      lastEvents should ===(Set(OnComplete))
    }

    "postStop when pushAndFinish called if upstream completes with pushAndFinish" in new OneBoundedSetup[String](
      new PushFinishStage(onPostStop = () ⇒ testActor ! "stop")) {

      lastEvents() should be(Set.empty)

      downstream.requestOne()
      lastEvents() should be(Set(RequestOne))

      upstream.onNextAndComplete("foo")
      lastEvents() should be(Set(OnNext("foo"), OnComplete))
      expectMsg("stop")
    }

    "postStop when pushAndFinish called with pushAndFinish if indirect upstream completes with pushAndFinish" in new OneBoundedSetup[String](
      Map((x: Any) ⇒ x, stoppingDecider).toGS,
      new PushFinishStage(onPostStop = () ⇒ testActor ! "stop"),
      Map((x: Any) ⇒ x, stoppingDecider).toGS) {

      lastEvents() should be(Set.empty)

      downstream.requestOne()
      lastEvents() should be(Set(RequestOne))

      upstream.onNextAndComplete("foo")
      lastEvents() should be(Set(OnNext("foo"), OnComplete))
      expectMsg("stop")
    }

    "postStop when pushAndFinish called with pushAndFinish if upstream completes with pushAndFinish and downstream immediately pulls" in new OneBoundedSetup[String](
      new PushFinishStage(onPostStop = () ⇒ testActor ! "stop"),
      Fold("", (x: String, y: String) ⇒ x + y, stoppingDecider).toGS) {

      lastEvents() should be(Set.empty)

      downstream.requestOne()
      lastEvents() should be(Set(RequestOne))

      upstream.onNextAndComplete("foo")
      lastEvents() should be(Set(OnNext("foo"), OnComplete))
      expectMsg("stop")
    }

  }

  private[akka] case class PreStartAndPostStopIdentity[T](
    onStart: () ⇒ Unit = () ⇒ (),
    onStop: () ⇒ Unit = () ⇒ (),
    onUpstreamCompleted: () ⇒ Unit = () ⇒ (),
    onUpstreamFailed: Throwable ⇒ Unit = ex ⇒ ()) extends SimpleLinearGraphStage[T] {

    override def createLogic(attributes: Attributes): GraphStageLogic =
      new GraphStageLogic(shape) with InHandler with OutHandler {
        override def preStart(): Unit = onStart()
        override def postStop(): Unit = onStop()

        override def onPush(): Unit = push(out, grab(in))
        override def onPull(): Unit = pull(in)

        override def onUpstreamFinish(): Unit = {
          onUpstreamCompleted()
          super.onUpstreamFinish()
        }

        override def onUpstreamFailure(cause: Throwable): Unit = {
          onUpstreamFailed(cause)
          super.onUpstreamFailure(cause)
        }

        setHandlers(in, out, this)
      }

    override def toString = "PreStartAndPostStopIdentity"
  }

  private[akka] case class PreStartFailer[T](pleaseThrow: () ⇒ Unit) extends SimpleLinearGraphStage[T] {

    override def createLogic(attributes: Attributes): GraphStageLogic =
      new GraphStageLogic(shape) with InHandler with OutHandler {
        override def preStart(): Unit = pleaseThrow()

        override def onPush(): Unit = push(out, grab(in))
        override def onPull(): Unit = pull(in)

        setHandlers(in, out, this)
      }

    override def toString = "PreStartFailer"
  }

  private[akka] case class PostStopFailer[T](pleaseThrow: () ⇒ Unit) extends SimpleLinearGraphStage[T] {

    override def createLogic(attributes: Attributes): GraphStageLogic =
      new GraphStageLogic(shape) with InHandler with OutHandler {
        override def onUpstreamFinish(): Unit = completeStage()

        override def onPush(): Unit = push(out, grab(in))
        override def onPull(): Unit = pull(in)

        override def postStop(): Unit = pleaseThrow()

        setHandlers(in, out, this)
      }

    override def toString = "PostStopFailer"
  }

  // This test is related to issue #17351
  private[akka] class PushFinishStage(onPostStop: () ⇒ Unit = () ⇒ ()) extends SimpleLinearGraphStage[Any] {

    override def createLogic(attributes: Attributes): GraphStageLogic =
      new GraphStageLogic(shape) with InHandler with OutHandler {
        override def onPush(): Unit = {
          push(out, grab(in))
          completeStage()
        }
        override def onPull(): Unit = pull(in)

        override def onUpstreamFinish(): Unit = failStage(TE("Cannot happen"))

        override def postStop(): Unit = onPostStop()

        setHandlers(in, out, this)
      }

    override def toString = "PushFinish"
  }
}