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

package jdocs.cluster;

import akka.actor.AbstractActor;
import akka.cluster.Cluster;
import akka.cluster.ClusterEvent;
import akka.cluster.ClusterEvent.MemberEvent;
import akka.cluster.ClusterEvent.MemberUp;
import akka.cluster.ClusterEvent.MemberRemoved;
import akka.cluster.ClusterEvent.UnreachableMember;
import akka.event.Logging;
import akka.event.LoggingAdapter;

public class SimpleClusterListener extends AbstractActor {
  LoggingAdapter log = Logging.getLogger(getContext().getSystem(), this);
  Cluster cluster = Cluster.get(getContext().getSystem());

  //subscribe to cluster changes
  @Override
  public void preStart() {
    //#subscribe
    cluster.subscribe(getSelf(), ClusterEvent.initialStateAsEvents(), 
        MemberEvent.class, UnreachableMember.class);
    //#subscribe
  }

  //re-subscribe when restart
  @Override
  public void postStop() {
    cluster.unsubscribe(getSelf());
  }

  @Override
  public Receive createReceive() {
    return receiveBuilder()
      .match(MemberUp.class, mUp -> {
        log.info("Member is Up: {}", mUp.member());
      })
      .match(UnreachableMember.class, mUnreachable -> {
        log.info("Member detected as unreachable: {}", mUnreachable.member());
      })
      .match(MemberRemoved.class, mRemoved -> {
        log.info("Member is Removed: {}", mRemoved.member());
      })
      .match(MemberEvent.class, message -> {
        // ignore
      })
      .build();
  }
}
