/**
 * Copyright (C) 2014-2015 Typesafe Inc. <http://www.typesafe.com>
 */

package akka.persistence.journal

import akka.actor.Actor
import akka.persistence.{ Persistence, PersistentEnvelope, PersistentRepr }
import scala.collection.immutable
import akka.persistence.AtomicWrite

private[akka] trait WriteJournalBase {
  this: Actor ⇒

  val persistence = Persistence(context.system)
  private val eventAdapters = persistence.adaptersFor(self)

  protected def preparePersistentBatch(rb: immutable.Seq[PersistentEnvelope]): immutable.Seq[AtomicWrite] =
    rb.collect { // collect instead of flatMap to avoid Some allocations
      case a: AtomicWrite ⇒
        // don't store sender
        a.copy(payload = a.payload.map(p ⇒ adaptToJournal(p.update(sender = Actor.noSender))))
    }

  /** INTERNAL API */
  private[akka] final def adaptFromJournal(repr: PersistentRepr): immutable.Seq[PersistentRepr] =
    eventAdapters.get(repr.payload.getClass).fromJournal(repr.payload, repr.manifest).events map { adaptedPayload ⇒
      repr.withPayload(adaptedPayload)
    }

  /** INTERNAL API */
  private[akka] final def adaptToJournal(repr: PersistentRepr): PersistentRepr = {
    val payload = repr.payload
    val adapter = eventAdapters.get(payload.getClass)

    // IdentityEventAdapter returns "" as manifest and normally the incoming PersistentRepr
    // doesn't have an assigned manifest, but when WriteMessages is sent directly to the
    // journal for testing purposes we want to preserve the original manifest instead of
    // letting IdentityEventAdapter clearing it out.
    if (adapter == IdentityEventAdapter || adapter.isInstanceOf[NoopWriteEventAdapter])
      repr
    else {
      repr.withPayload(adapter.toJournal(payload)).withManifest(adapter.manifest(payload))
    }
  }

}
