case class RegisterWorker(val id : String, val workerHost : String, val memory : String, val cores : String)
case class HeartBeat(val workid : String)
case class CheckOfTimeOutWorker()
case class RegisteredWorker(val workerHost : String)
case class SendHeartBeat()

import akka.actor.{Actor, ActorSystem, Props}
import com.typesafe.config.ConfigFactory
import scala.collection.mutable
import scala.concurrent.duration._
import scala.concurrent.ExecutionContext.Implicits.global


class Master extends Actor{
  //保存 WorkerID 和 Work 信息的 map
  val idToWorker = new mutable.HashMap[String, WorkerInfo]
  //保存所有 Worker 信息的 Set
  val workers = new mutable.HashSet[WorkerInfo]
  //Worker 超时时间
  val WORKER_TIMEOUT = 10 * 1000
  //构造方法执行完执行一次
  override def preStart(): Unit = {
    //启动定时器，定时执行
    context.system.scheduler.schedule(5 millis, WORKER_TIMEOUT millis, self, CheckOfTimeOutWorker)
  }
  //该方法会被反复执行，用于接收消息，通过 case class 模式匹配接收消息
  override def receive: Receive = {
    //Worker 向 Master 发送的注册消息
    case RegisterWorker(id, workerHost, memory, cores) => {
      if(!idToWorker.contains(id)) {
        val worker = new WorkerInfo(id, workerHost, memory, cores)
        workers.add(worker)
        idToWorker(id) = worker
        println("new register worker: "+worker)
        sender ! RegisteredWorker(worker.id)
      }
    }
    //Worker 向 Master 发送的心跳消息
    case HeartBeat(workerId) => {
      val workerInfo = idToWorker(workerId)
      println("get heartbeat message from: "+workerInfo)
      workerInfo.lastHeartbeat = System.currentTimeMillis()
    }
    //Master 自己向自己发送的定期检查超时 Worker 的消息
    case CheckOfTimeOutWorker => {
      val currentTime = System.currentTimeMillis()
      val toRemove = workers.filter(w => currentTime - w.lastHeartbeat > WORKER_TIMEOUT).toArray
      for(worker <- toRemove){
        workers -= worker
        idToWorker.remove(worker.id)
      }
      println("worker size: " + workers.size)
    }
  }
}
object Master {
  //程序执行入口
  def main(args: Array[String]) {
    val host = "localhost"
    val port = 8888
    //创建 ActorSystem 的必要参数
    val configStr =
      s"""
         |akka.actor.provider = "akka.remote.RemoteActorRefProvider"
         |akka.remote.netty.tcp.hostname = "$host"
         |akka.remote.netty.tcp.port = "$port"
""".stripMargin
    val config = ConfigFactory.parseString(configStr)
    //ActorSystem 是单例的，用来创建 Actor
    val actorSystem = ActorSystem.create("MasterActorSystem", config)
    //启动 Actor，Master 会被实例化，生命周期方法会被调用
    actorSystem.actorOf(Props[Master], "Master")
  }
}