/*
 * Created on Apr 5, 2005
 * Created by Alon Rohter
 * Copyright (C) 2005, 2006 Aelitis, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 * 
 * AELITIS, SAS au capital de 46,603.30 euros
 * 8 Allee Lenotre, La Grille Royale, 78600 Le Mesnil le Roi, France.
 *
 */

package com.aelitis.azureus.core.peermanager.uploadslots;

import java.util.*;

import org.gudy.azureus2.core3.peer.impl.PEPeerTransport;
import org.gudy.azureus2.core3.util.*;

import com.aelitis.azureus.core.peermanager.unchoker.UnchokerUtil;



/**
 * Unchoker implementation to be used while in seeding mode.
 */
public class SeedingRanker {
	

  public SeedingRanker() {
    /* nothing */
  }
  
  
  private PEPeerTransport getNextOptimisticPeerExec( ArrayList all_peers ) {
  	
  	if( all_peers.isEmpty() )  {  //no connected peers
  		Debug.out( "all_peers.isEmpty()" );
  		return null;
  	}  	
  	
  	int pos = RandomUtils.nextInt( all_peers.size() );  //pick a random peer to start
  	
  	for( int i=0; i < all_peers.size(); i++ ) {  //ensure we only loop once
  		
  		PEPeerTransport peer = (PEPeerTransport)all_peers.get( pos );  //get next potential peer
  		
  		if( peer.isChokedByMe() && UnchokerUtil.isUnchokable( peer, true ) ) {   //filter out peers already unchoked, and unchokable
  			
  			return peer;  //found the next optimistic!  			
  		}
  		
  		pos++;  //try next
  		
  		if( pos >= all_peers.size() ) {  //loop 'round if necessary
  			pos = 0;
  		}  		
  	}
  	
  	Debug.out( "no optimistic-able seeding peers found" );
  	return null;  	
  }
  
  
  public PEPeerTransport getNextOptimisticPeer( ArrayList all_peers ) {
  	PEPeerTransport picked = getNextOptimisticPeerExec( all_peers );
  	
  	//TODO test to see if peers really are picked evenly
  	
  	return picked;  	
  }
  
  
  
}