/*
 * Copyright (C) 2015-2018 Lightbend Inc. <https://www.lightbend.com>
 */

package akka.cluster.singleton.protobuf

import akka.actor.ExtendedActorSystem
import akka.cluster.singleton.ClusterSingletonManager.Internal.HandOverDone
import akka.cluster.singleton.ClusterSingletonManager.Internal.HandOverInProgress
import akka.cluster.singleton.ClusterSingletonManager.Internal.HandOverToMe
import akka.cluster.singleton.ClusterSingletonManager.Internal.TakeOverFromMe
import akka.serialization.BaseSerializer
import akka.serialization.SerializationExtension
import akka.serialization.SerializerWithStringManifest
import java.io.NotSerializableException

/**
 * INTERNAL API: Serializer of ClusterSingleton messages.
 * It is actually not using protobuf, but if we add more messages to
 * the ClusterSingleton we want to make protobuf representations of them.
 */
private[akka] class ClusterSingletonMessageSerializer(val system: ExtendedActorSystem)
  extends SerializerWithStringManifest with BaseSerializer {

  private lazy val serialization = SerializationExtension(system)

  private val HandOverToMeManifest = "A"
  private val HandOverInProgressManifest = "B"
  private val HandOverDoneManifest = "C"
  private val TakeOverFromMeManifest = "D"

  private val emptyByteArray = Array.empty[Byte]

  private val fromBinaryMap = collection.immutable.HashMap[String, Array[Byte] ⇒ AnyRef](
    HandOverToMeManifest → { _ ⇒ HandOverToMe },
    HandOverInProgressManifest → { _ ⇒ HandOverInProgress },
    HandOverDoneManifest → { _ ⇒ HandOverDone },
    TakeOverFromMeManifest → { _ ⇒ TakeOverFromMe })

  override def manifest(obj: AnyRef): String = obj match {
    case HandOverToMe       ⇒ HandOverToMeManifest
    case HandOverInProgress ⇒ HandOverInProgressManifest
    case HandOverDone       ⇒ HandOverDoneManifest
    case TakeOverFromMe     ⇒ TakeOverFromMeManifest
    case _ ⇒
      throw new IllegalArgumentException(s"Can't serialize object of type ${obj.getClass} in [${getClass.getName}]")
  }

  override def toBinary(obj: AnyRef): Array[Byte] = obj match {
    case HandOverToMe       ⇒ emptyByteArray
    case HandOverInProgress ⇒ emptyByteArray
    case HandOverDone       ⇒ emptyByteArray
    case TakeOverFromMe     ⇒ emptyByteArray
    case _ ⇒
      throw new IllegalArgumentException(s"Can't serialize object of type ${obj.getClass} in [${getClass.getName}]")
  }

  override def fromBinary(bytes: Array[Byte], manifest: String): AnyRef =
    fromBinaryMap.get(manifest) match {
      case Some(f) ⇒ f(bytes)
      case None ⇒ throw new NotSerializableException(
        s"Unimplemented deserialization of message with manifest [$manifest] in [${getClass.getName}]")
    }

}
