/*

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  *

  * The contents of this file are subject to the terms of either the GNU

  * General Public License Version 2 only ("GPL") or the Common

  * Development and Distribution License("CDDL") (collectively, the

  * "License"). You may not use this file except in compliance with the

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  * http://www.netbeans.org/cddl-gplv2.html

  * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the

  * specific language governing permissions and limitations under the

  * License.  When distributing the software, include this License Header

  * Notice in each file and include the License file at

  * nbbuild/licenses/CDDL-GPL-2-CP.  Sun designates this

  * particular file as subject to the "Classpath" exception as provided

  * by Sun in the GPL Version 2 section of the License file that

  * accompanied this code. If applicable, add the following below the

  * License Header, with the fields enclosed by brackets [] replaced by

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  * Contributor(s):

  *

  * Portions Copyrighted 2010 Martin Rexa

  */

 package cz.xelfi.quoridor.statistics;

 import java.util.Map;

 import java.util.HashMap;

 import java.util.List;

 import java.util.Collections;

 import java.util.ArrayList;

 import javax.xml.bind.annotation.XmlElement;

 import javax.xml.bind.annotation.XmlElementWrapper;

 import javax.xml.bind.annotation.XmlRootElement;

 import javax.xml.bind.annotation.XmlAccessType;

 import javax.xml.bind.annotation.XmlAccessorType;

 /**

  *

  * @author Martin Rexa

  */

 @XmlRootElement

 @XmlAccessorType(XmlAccessType.FIELD)

 public class EloList {

     static int INITIAL_ELO = 1250;

     static int MAX_ELO_DIFF = 400;

     static int KVAL_START = 25;

     static int KVAL_FOLLOW = 10;

     static int KVAL_LIMIT = 30;

     private Map<String, Double> players;

     private Map<String, Integer> playerGames;

     public EloList () {

         players = new HashMap<String, Double>();

         playerGames = new HashMap<String, Integer>();

     }

     @XmlElementWrapper(name="elolist")

     @XmlElement(name="item")

     public List<EloEntry> getFinalList(){

         List<EloEntry> finalList = new ArrayList<EloEntry>();

         for (Map.Entry<String, Double> player : players.entrySet()){

             finalList.add(new EloEntry(player.getKey(), player.getValue(), playerGames.get(player.getKey())));

         }

         Collections.sort(finalList, EloEntry.BEST_FIRST);

         return finalList;

     }

     public EloList putResult(String winner, String looser){

         double wElo = getElo(winner);

         double lElo = getElo(looser);

         double eloDiff = wElo - lElo;

         if(eloDiff < - MAX_ELO_DIFF)

             eloDiff = - MAX_ELO_DIFF;

         if(eloDiff > MAX_ELO_DIFF)

             eloDiff = MAX_ELO_DIFF;

         double wDiff = Math.round(100 * getKVal(winner) * (1 - (1 / (1 + Math.pow(10, -eloDiff / MAX_ELO_DIFF)))));

         wDiff /= 100.0;

         double lDiff = Math.round(100 * getKVal(looser) * (0 - (1 / (1 + Math.pow(10, eloDiff / MAX_ELO_DIFF)))));

         lDiff /= 100.0;

         players.put(winner, wElo + wDiff);

         players.put(looser, lElo + lDiff);

         return this;

     }

     public double getElo(String player){

         Double elo = players.get(player);

         return (elo == null) ? INITIAL_ELO : elo;

     }

     private int getKVal(String player){

         Integer games = playerGames.get(player);

         int g = (games == null) ? 0 : games;

         // Side effect, method should not be called more times for the same game/player

         playerGames.put(player, g + 1);

         return g < KVAL_LIMIT ? KVAL_START : KVAL_FOLLOW;

     }

 }