/**
 * Copyright (C) 2009-2017 Lightbend Inc. <http://www.lightbend.com>
 */

package akka.serialization

import com.typesafe.config.Config
import akka.actor._
import akka.event.{ LogMarker, Logging, LoggingAdapter }
import java.util.concurrent.ConcurrentHashMap

import scala.collection.mutable.ArrayBuffer
import java.io.NotSerializableException

import scala.util.{ DynamicVariable, Failure, Try }
import scala.collection.immutable
import scala.util.control.NonFatal
import scala.util.Success
import java.nio.ByteBuffer
import java.util.concurrent.atomic.AtomicReference

import scala.annotation.tailrec
import java.util.NoSuchElementException
import akka.annotation.InternalApi

object Serialization {

  /**
   * Tuple that represents mapping from Class to Serializer
   */
  type ClassSerializer = (Class[_], Serializer)

  /**
   * This holds a reference to the current transport serialization information used for
   * serializing local actor refs.
   * INTERNAL API
   */
  private[akka] val currentTransportInformation = new DynamicVariable[Information](null)

  class Settings(val config: Config) {
    val Serializers: Map[String, String] = configToMap(config.getConfig("akka.actor.serializers"))
    val SerializationBindings: Map[String, String] = {
      val defaultBindings = config.getConfig("akka.actor.serialization-bindings")
      val bindings =
        if (config.getBoolean("akka.actor.enable-additional-serialization-bindings") ||
          !config.getBoolean("akka.actor.allow-java-serialization") ||
          config.hasPath("akka.remote.artery.enabled") && config.getBoolean("akka.remote.artery.enabled")) {
          defaultBindings.withFallback(config.getConfig("akka.actor.additional-serialization-bindings"))
        } else {
          defaultBindings
        }
      configToMap(bindings)
    }

    private final def configToMap(cfg: Config): Map[String, String] = {
      import scala.collection.JavaConverters._
      cfg.root.unwrapped.asScala.toMap map { case (k, v) ⇒ (k → v.toString) }
    }
  }

  /**
   * Serialization information needed for serializing local actor refs.
   * INTERNAL API
   */
  private[akka] final case class Information(address: Address, system: ActorSystem)

  /**
   * The serialized path of an actorRef, based on the current transport serialization information.
   * If there is no external address available for the requested address then the systems default
   * address will be used.
   */
  def serializedActorPath(actorRef: ActorRef): String = {
    val path = actorRef.path
    val originalSystem: ExtendedActorSystem = actorRef match {
      case a: ActorRefWithCell ⇒ a.underlying.system.asInstanceOf[ExtendedActorSystem]
      case _                   ⇒ null
    }
    Serialization.currentTransportInformation.value match {
      case null ⇒ originalSystem match {
        case null ⇒ path.toSerializationFormat
        case system ⇒
          try path.toSerializationFormatWithAddress(system.provider.getDefaultAddress)
          catch { case NonFatal(_) ⇒ path.toSerializationFormat }
      }
      case Information(address, system) ⇒
        if (originalSystem == null || originalSystem == system)
          path.toSerializationFormatWithAddress(address)
        else {
          val provider = originalSystem.provider
          path.toSerializationFormatWithAddress(provider.getExternalAddressFor(address).getOrElse(provider.getDefaultAddress))
        }
    }
  }
}

/**
 * Serialization module. Contains methods for serialization and deserialization as well as
 * locating a Serializer for a particular class as defined in the mapping in the configuration.
 */
class Serialization(val system: ExtendedActorSystem) extends Extension {
  import Serialization._

  val settings = new Settings(system.settings.config)
  val AllowJavaSerialization: Boolean = system.settings.AllowJavaSerialization

  private[this] val _log = Logging.withMarker(system, getClass.getName)
  val log: LoggingAdapter = _log
  private val manifestCache = new AtomicReference[Map[String, Option[Class[_]]]](Map.empty[String, Option[Class[_]]])

  /**
   * Serializes the given AnyRef/java.lang.Object according to the Serialization configuration
   * to either an Array of Bytes or an Exception if one was thrown.
   */
  def serialize(o: AnyRef): Try[Array[Byte]] = Try(findSerializerFor(o).toBinary(o))

  /**
   * Deserializes the given array of bytes using the specified serializer id,
   * using the optional type hint to the Serializer.
   * Returns either the resulting object or an Exception if one was thrown.
   */
  def deserialize[T](bytes: Array[Byte], serializerId: Int, clazz: Option[Class[_ <: T]]): Try[T] =
    Try {
      val serializer = try getSerializerById(serializerId) catch {
        case _: NoSuchElementException ⇒ throw new NotSerializableException(
          s"Cannot find serializer with id [$serializerId]. The most probable reason is that the configuration entry " +
            "akka.actor.serializers is not in synch between the two systems.")
      }
      serializer.fromBinary(bytes, clazz).asInstanceOf[T]
    }

  /**
   * Deserializes the given array of bytes using the specified serializer id,
   * using the optional type hint to the Serializer.
   * Returns either the resulting object or an Exception if one was thrown.
   */
  def deserialize(bytes: Array[Byte], serializerId: Int, manifest: String): Try[AnyRef] =
    Try {
      val serializer = try getSerializerById(serializerId) catch {
        case _: NoSuchElementException ⇒ throw new NotSerializableException(
          s"Cannot find serializer with id [$serializerId]. The most probable reason is that the configuration entry " +
            "akka.actor.serializers is not in synch between the two systems.")
      }
      deserializeByteArray(bytes, serializer, manifest)
    }

  private def deserializeByteArray(bytes: Array[Byte], serializer: Serializer, manifest: String): AnyRef = {

    @tailrec def updateCache(cache: Map[String, Option[Class[_]]], key: String, value: Option[Class[_]]): Boolean = {
      manifestCache.compareAndSet(cache, cache.updated(key, value)) ||
        updateCache(manifestCache.get, key, value) // recursive, try again
    }

    serializer match {
      case s2: SerializerWithStringManifest ⇒ s2.fromBinary(bytes, manifest)
      case s1 ⇒
        if (manifest == "")
          s1.fromBinary(bytes, None)
        else {
          val cache = manifestCache.get
          cache.get(manifest) match {
            case Some(cachedClassManifest) ⇒ s1.fromBinary(bytes, cachedClassManifest)
            case None ⇒
              system.dynamicAccess.getClassFor[AnyRef](manifest) match {
                case Success(classManifest) ⇒
                  val classManifestOption: Option[Class[_]] = Some(classManifest)
                  updateCache(cache, manifest, classManifestOption)
                  s1.fromBinary(bytes, classManifestOption)
                case Failure(e) ⇒
                  throw new NotSerializableException(
                    s"Cannot find manifest class [$manifest] for serializer with id [${serializer.identifier}].")
              }
          }
        }
    }
  }

  /**
   * Deserializes the given ByteBuffer of bytes using the specified serializer id,
   * using the optional type hint to the Serializer.
   * Returns either the resulting object or throws an exception if deserialization fails.
   */
  @throws(classOf[NotSerializableException])
  def deserializeByteBuffer(buf: ByteBuffer, serializerId: Int, manifest: String): AnyRef = {
    val serializer = try getSerializerById(serializerId) catch {
      case _: NoSuchElementException ⇒ throw new NotSerializableException(
        s"Cannot find serializer with id [$serializerId]. The most probable reason is that the configuration entry " +
          "akka.actor.serializers is not in synch between the two systems.")
    }
    serializer match {
      case ser: ByteBufferSerializer ⇒
        ser.fromBinary(buf, manifest)
      case _ ⇒
        val bytes = new Array[Byte](buf.remaining())
        buf.get(bytes)
        deserializeByteArray(bytes, serializer, manifest)
    }
  }

  /**
   * Deserializes the given array of bytes using the specified type to look up what Serializer should be used.
   * Returns either the resulting object or an Exception if one was thrown.
   */
  def deserialize[T](bytes: Array[Byte], clazz: Class[T]): Try[T] =
    Try(serializerFor(clazz).fromBinary(bytes, Some(clazz)).asInstanceOf[T])

  /**
   * Returns the Serializer configured for the given object, returns the NullSerializer if it's null.
   *
   * Throws akka.ConfigurationException if no `serialization-bindings` is configured for the
   *   class of the object.
   */
  def findSerializerFor(o: AnyRef): Serializer =
    if (o eq null) NullSerializer else serializerFor(o.getClass)

  /**
   * Returns the configured Serializer for the given Class. The configured Serializer
   * is used if the configured class `isAssignableFrom` from the `clazz`, i.e.
   * the configured class is a super class or implemented interface. In case of
   * ambiguity it is primarily using the most specific configured class,
   * and secondly the entry configured first.
   *
   * Throws java.io.NotSerializableException if no `serialization-bindings` is configured for the class.
   */
  @throws(classOf[NotSerializableException])
  def serializerFor(clazz: Class[_]): Serializer =
    serializerMap.get(clazz) match {
      case null ⇒ // bindings are ordered from most specific to least specific
        def unique(possibilities: immutable.Seq[(Class[_], Serializer)]): Boolean =
          possibilities.size == 1 ||
            (possibilities forall (_._1 isAssignableFrom possibilities(0)._1)) ||
            (possibilities forall (_._2 == possibilities(0)._2))

        val ser = {
          bindings.filter {
            case (c, _) ⇒ c isAssignableFrom clazz
          } match {
            case immutable.Seq() ⇒
              throw new NotSerializableException(s"No configured serialization-bindings for class [${clazz.getName}]")
            case possibilities ⇒
              if (unique(possibilities))
                possibilities.head._2
              else {
                // give JavaSerializer lower priority if multiple serializers found
                val possibilitiesWithoutJavaSerializer = possibilities.filter {
                  case (_, _: JavaSerializer)         ⇒ false
                  case (_, _: DisabledJavaSerializer) ⇒ false
                  case _                              ⇒ true
                }
                if (possibilitiesWithoutJavaSerializer.isEmpty) {
                  // shouldn't happen
                  throw new NotSerializableException(s"More than one JavaSerializer configured for class [${clazz.getName}]")
                }

                if (!unique(possibilitiesWithoutJavaSerializer)) {
                  _log.warning(LogMarker.Security, "Multiple serializers found for [{}], choosing first of: [{}]",
                    clazz.getName,
                    possibilitiesWithoutJavaSerializer.map { case (_, s) ⇒ s.getClass.getName }.mkString(", "))
                }
                possibilitiesWithoutJavaSerializer.head._2

              }

          }
        }

        serializerMap.putIfAbsent(clazz, ser) match {
          case null ⇒
            if (shouldWarnAboutJavaSerializer(clazz, ser)) {
              _log.warning(LogMarker.Security, "Using the default Java serializer for class [{}] which is not recommended because of " +
                "performance implications. Use another serializer or disable this warning using the setting " +
                "'akka.actor.warn-about-java-serializer-usage'", clazz.getName)
            }
            log.debug("Using serializer [{}] for message [{}]", ser.getClass.getName, clazz.getName)
            ser
          case some ⇒ some
        }
      case ser ⇒ ser
    }

  /**
   * Tries to load the specified Serializer by the fully-qualified name; the actual
   * loading is performed by the system’s [[akka.actor.DynamicAccess]].
   */
  def serializerOf(serializerFQN: String): Try[Serializer] = {
    // We override each instantiation of the JavaSerializer with the "disabled" serializer which will log warnings if used.
    val fqn =
      if (!system.settings.AllowJavaSerialization && serializerFQN == classOf[JavaSerializer].getName) {
        log.debug("Replacing JavaSerializer with DisabledJavaSerializer, " +
          "due to `akka.actor.allow-java-serialization = off`.")
        classOf[DisabledJavaSerializer].getName
      } else serializerFQN

    system.dynamicAccess.createInstanceFor[Serializer](fqn, List(classOf[ExtendedActorSystem] → system)) recoverWith {
      case _: NoSuchMethodException ⇒
        system.dynamicAccess.createInstanceFor[Serializer](fqn, Nil)
    }
  }

  /**
   * Programmatically defined serializers
   */
  private val serializerDetails: immutable.Seq[SerializerDetails] =
    (system.settings.setup.get[SerializationSetup] match {
      case None          ⇒ Vector.empty
      case Some(setting) ⇒ setting.createSerializers(system)
    }) collect {
      case det: SerializerDetails if isDisallowedJavaSerializer(det.serializer) ⇒
        log.debug("Replacing JavaSerializer with DisabledJavaSerializer, " +
          "due to `akka.actor.allow-java-serialization = off`.")
        SerializerDetails(det.alias, new DisabledJavaSerializer(system), det.useFor)
      case det ⇒ det
    }

  /**
   * A Map of serializer from alias to implementation (class implementing akka.serialization.Serializer)
   * By default always contains the following mapping: "java" -> akka.serialization.JavaSerializer
   */
  private val serializers: Map[String, Serializer] = {
    val fromConfig = for ((k: String, v: String) ← settings.Serializers) yield k → serializerOf(v).get
    val result = fromConfig ++ serializerDetails.map(d ⇒ d.alias → d.serializer)
    ensureOnlyAllowedSerializers(result.map { case (_, ser) ⇒ ser }(collection.breakOut))
    result
  }

  /**
   *  bindings is a Seq of tuple representing the mapping from Class to Serializer.
   *  It is primarily ordered by the most specific classes first, and secondly in the configured order.
   */
  private[akka] val bindings: immutable.Seq[ClassSerializer] = {
    val fromConfig = for {
      (className: String, alias: String) ← settings.SerializationBindings
      if alias != "none" && checkGoogleProtobuf(className)
    } yield (system.dynamicAccess.getClassFor[Any](className).get, serializers(alias))

    val fromSettings = serializerDetails.flatMap { detail ⇒
      detail.useFor.map(clazz ⇒ clazz → detail.serializer)
    }

    val result = sort(fromConfig ++ fromSettings)
    ensureOnlyAllowedSerializers(result.map { case (_, ser) ⇒ ser }(collection.breakOut))
    result
  }

  private def ensureOnlyAllowedSerializers(iter: Iterator[Serializer]): Unit = {
    if (!system.settings.AllowJavaSerialization) {
      require(iter.forall(!isDisallowedJavaSerializer(_)), "Disallowed JavaSerializer binding.")
    }
  }

  // com.google.protobuf serialization binding is only used if the class can be loaded,
  // i.e. com.google.protobuf dependency has been added in the application project.
  // The reason for this special case is for backwards compatibility so that we still can
  // include "com.google.protobuf.GeneratedMessage" = proto in configured serialization-bindings.
  private def checkGoogleProtobuf(className: String): Boolean =
    (!className.startsWith("com.google.protobuf") || system.dynamicAccess.getClassFor[Any](className).isSuccess)

  /**
   * Sort so that subtypes always precede their supertypes, but without
   * obeying any order between unrelated subtypes (insert sort).
   */
  private def sort(in: Iterable[ClassSerializer]): immutable.Seq[ClassSerializer] =
    ((new ArrayBuffer[ClassSerializer](in.size) /: in) { (buf, ca) ⇒
      buf.indexWhere(_._1 isAssignableFrom ca._1) match {
        case -1 ⇒ buf append ca
        case x  ⇒ buf insert (x, ca)
      }
      buf
    }).to[immutable.Seq]

  /**
   * serializerMap is a Map whose keys is the class that is serializable and values is the serializer
   * to be used for that class.
   */
  private val serializerMap: ConcurrentHashMap[Class[_], Serializer] =
    (new ConcurrentHashMap[Class[_], Serializer] /: bindings) { case (map, (c, s)) ⇒ map.put(c, s); map }

  /**
   * Maps from a Serializer Identity (Int) to a Serializer instance (optimization)
   */
  val serializerByIdentity: Map[Int, Serializer] =
    Map(NullSerializer.identifier → NullSerializer) ++ serializers map { case (_, v) ⇒ (v.identifier, v) }

  /**
   * Serializers with id 0 - 1023 are stored in an array for quick allocation free access
   */
  private val quickSerializerByIdentity: Array[Serializer] = {
    val size = 1024
    val table = new Array[Serializer](size)
    serializerByIdentity.foreach {
      case (id, ser) ⇒ if (0 <= id && id < size) table(id) = ser
    }
    table
  }

  /**
   * @throws `NoSuchElementException` if no serializer with given `id`
   */
  private def getSerializerById(id: Int): Serializer = {
    if (0 <= id && id < quickSerializerByIdentity.length) {
      quickSerializerByIdentity(id) match {
        case null ⇒ throw new NoSuchElementException(s"key not found: $id")
        case ser  ⇒ ser
      }
    } else
      serializerByIdentity(id)
  }

  private val isJavaSerializationWarningEnabled = settings.config.getBoolean("akka.actor.warn-about-java-serializer-usage")
  private val isWarningOnNoVerificationEnabled = settings.config.getBoolean("akka.actor.warn-on-no-serialization-verification")

  private def isDisallowedJavaSerializer(serializer: Serializer): Boolean = {
    serializer.isInstanceOf[JavaSerializer] && !system.settings.AllowJavaSerialization
  }

  /**
   * INTERNAL API
   */
  @InternalApi private[akka] def shouldWarnAboutJavaSerializer(serializedClass: Class[_], serializer: Serializer) = {

    def suppressWarningOnNonSerializationVerification(serializedClass: Class[_]) = {
      //suppressed, only when warn-on-no-serialization-verification = off, and extending NoSerializationVerificationNeeded
      !isWarningOnNoVerificationEnabled && classOf[NoSerializationVerificationNeeded].isAssignableFrom(serializedClass)
    }

    isJavaSerializationWarningEnabled &&
      (serializer.isInstanceOf[JavaSerializer] || serializer.isInstanceOf[DisabledJavaSerializer]) &&
      !serializedClass.getName.startsWith("akka.") &&
      !serializedClass.getName.startsWith("java.lang.") &&
      !suppressWarningOnNonSerializationVerification(serializedClass)
  }
}