Someone

/**
 * 
 */
package net.sf.l2j.gameserver.util;

import java.util.Collection;
import java.util.Iterator;

import javolution.util.FastMap;
import javolution.util.FastSet;

import net.sf.l2j.gameserver.model.L2PcInstance;
import net.sf.l2j.gameserver.model.L2Character;
import net.sf.l2j.gameserver.model.L2Object;
import net.sf.l2j.gameserver.model.L2World;
import net.sf.l2j.gameserver.model.L2WorldRegion;
import net.sf.l2j.util.Point3D;
import net.sf.l2j.Config;


/**
 * @author Layane
 * @version: $
 * 
 * MRU Alg,Zone check,Distance check
 */
public class NpcKnownList
{
    private static final int MINIMUM_UPDATE_DISTANCE_SQUARED = Config.MINIMUM_UPDATE_DISTANCE * Config.MINIMUM_UPDATE_DISTANCE;
    
    protected FastMap<L2PcInstance,L2PcInstance> _knownPlayers;
    protected Point3D _lastUpdatePosition;
    protected L2Character _owner;
    
    public NpcKnownList(L2Character owner)
    {
        _lastUpdatePosition = new Point3D(owner.getWorldPosition());
        _owner = owner;
    }
    
    public void add(L2Object object)
    {
        if (object instanceof L2PcInstance)
        {
            addPlayer((L2PcInstance)object);
        }
    }
    
    public synchronized final void addPlayer(L2PcInstance player)
    {
        if (player == null)
            return;
        
        if (_knownPlayers == null)
            _knownPlayers = new FastMap<L2PcInstance,L2PcInstance>().setShared(true);
        
        _knownPlayers.put(player,player);
    }
    
    public void remove(L2Object object)
    {
        if (object instanceof L2PcInstance)
        {
            removePlayer((L2PcInstance)object);
        }
    }
    
    public final void removePlayer(L2PcInstance player)
    {
        if (player == null || _knownPlayers == null)
            return;
        
        _knownPlayers.remove(player);
    }
    
    public final boolean knowsPlayer(L2PcInstance player)
    {
        if (player == null || _knownPlayers == null)
            return false;
        
        return _knownPlayers.containsKey(player);
    }
    
    public final Collection<L2PcInstance> getKnownPlayers()
    {
        if (_knownPlayers == null)
            return null;
        
        return _knownPlayers.values();
    }
    
    
    public Collection getKnownObjects()
    {
        if (_knownPlayers == null)
            return null;
        
        return _knownPlayers.values();
    }
    
    public void clear()
    {
        if (_knownPlayers != null)
            _knownPlayers.clear();
    }
    
    public void update()
    {
        Point3D myPosition;
        synchronized (this)
        {
            myPosition = _owner.getWorldPosition();
            if (myPosition.distanceSquaredTo(_lastUpdatePosition) <= MINIMUM_UPDATE_DISTANCE_SQUARED)
                return;
            
            _lastUpdatePosition.setTo(myPosition);
        }
        
        //Forget distant objects
        for (L2PcInstance player : _knownPlayers.values())
        {
            if (_owner.getDistanceToForgetObject(player) > MINIMUM_UPDATE_DISTANCE_SQUARED)
            {
                player.removeKnownObject(_owner);
                _owner.removeKnownObject(player);
            }
        }
        
        //Find close objects
        L2World world = L2World.getInstance();
        int vision = _owner.getDistanceToWatchObject(null);
        
        int x = myPosition.getX();
        int y = myPosition.getY();
        
        FastSet<L2WorldRegion> adjZones = new FastSet<L2WorldRegion>();
        
        adjZones.add(_owner.getCurrentWorldRegion());
        adjZones.add(world.getRegion(x - vision, y + vision));
        adjZones.add(world.getRegion(x - vision, y - vision));
        adjZones.add(world.getRegion(x + vision, y + vision));
        adjZones.add(world.getRegion(x + vision, y - vision));
        adjZones.add(world.getRegion(x, y - vision));
        adjZones.add(world.getRegion(x, y + vision));
        adjZones.add(world.getRegion(x - vision, y));
        adjZones.add(world.getRegion(x + vision, y));
        
        Iterator<L2PcInstance> it;
        L2PcInstance player;
        for (L2WorldRegion region : adjZones)
        {
            it = region.iterateAllPlayers();
            while(it.hasNext())
            {
                player = it.next();
                if (myPosition.distanceSquaredTo(player.getWorldPosition()) <= vision)
                {
                    player.addKnownObject(_owner, null);
                    _owner.addKnownObject(player, null);
                }
            }
        }
        
    }
}