package org.apache.esme.actor

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import org.apache.esme.actor.Distributor.AddMessageToMailbox
import org.apache.esme.model._
import net.liftweb.http.ActorWatcher
import net.liftweb.util._
import Helpers._
import net.liftweb.common._
import net.liftweb.actor._

object PopStatsActor extends LiftActor {

  import scala.collection.mutable.Map
  
  private val actors: Map[StatParam,Map[Long,PopStatsActor]] = Map()
  
  protected def now = System.currentTimeMillis
  protected def messageHandler = {
    case StartStats(what, period, refresh) =>
      if (!actors.contains(what)) {
        actors(what) = Map()
      }
      val stat = actors(what)
      if(!stat.contains(period)) {
        val statActor = new PopStatsActor(period, refresh)
        stat(period) = statActor
        statActor ! StartUp
      }
    
    case StopStats(what, period) => // TODO: not used
    case TopStats(what, n, period) =>
      (for (stat <- actors.get(what);
            availableActor <- stat.get(period)) yield availableActor) match {
              case Some(statActor) => forwardMessageTo(Top(n), statActor)
              case _ => reply(Nil)
            }

    case IncrStats(what, hitItem) =>
      for (stat <- actors.get(what);
           statActor <- stat.values)
        statActor ! Hit(hitItem)
  }
  
  // do nothing
  def touch {
  }

  case object StartUp
  case object ByeBye
  case class Top(n: Int)
  case class Hit(id: Long)
  case object Expire
  
  case class StartStats(what: StatParam, period: Long, refresh: Long)
  case class StopStats(what: StatParam, period: Long)
  case class TopStats(what: StatParam, n: Byte, period: Long)
  case class IncrStats(what: StatParam, hitItem: Long)

  private class PopStatsActor(period: Long,
                              refreshInterval: Long) extends LiftActor {
    private var queue: List[StatEvent] = List()
    private var stats: Map[Long,Int] = Map()
    private var running = true

    protected def messageHandler = {
      case StartUp => ActorPing.schedule(this, Expire, refreshInterval)

      case ByeBye =>
        running = false
  
      case Hit(id) =>
        queue ::= StatEvent(id, now)
        stats += (id -> (stats.getOrElse(id,0) + 1))
        
      case Top(n) =>
        val topList = stats.toList.sortWith{
          case ((_,freq1),(_,freq2)) =>
            freq2 < freq1
        }.take(n)
      reply(topList)
      
      case Expire => {
        val (live, expired) = queue.partition(_.when + period > now)
        expired.foreach(stats -= _.id)
        ActorPing.schedule(this, Expire, refreshInterval)
        live
      }
    }
    
    case class StatEvent(id: Long, when: Long)
  }

}

sealed trait StatParam
case object ResendStat extends StatParam
case object LinkClickedStat extends StatParam