/*
* LumaQQ - Java QQ Client
*
* Copyright (C) 2004 luma <stubma@163.com>
*
* 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
*/
package edu.tsinghua.lumaqq.qq.packets.out;

import java.nio.ByteBuffer;

import edu.tsinghua.lumaqq.qq.PacketParseException;
import edu.tsinghua.lumaqq.qq.QQ;
import edu.tsinghua.lumaqq.qq.packets.OutPacket;

/**
 * <pre>
 * 獲取在線好友列表的請求包，格式為
 * 1. 頭部
 * 2. 1個字節，只有值為0x02或者0x03時服務器才有反應，不然都是返回0xFF
 *    經過初步的試驗，發現3得到的好友都是一些系統服務，號碼比如72000001到72000013，
 *    就是那些移動QQ，會員服務之類的；而2是用來得到好友的
 * 3. 1個字節，得到好友列表的位置，也就是position，這個position的含義和
 *    GetFriendListPacket中的position相同，只不過這個position單位是1 byte，
 *    當然也有可能GetFriendListPacket中的position也是1 byte，不好說
 * 4. 1個未知字節，設成0
 * 5. 2個未知字節，設成0
 * 6. 尾部
 * </pre>
 *
 * @author 馬若劼
 */
public class GetFriendOnlinePacket extends OutPacket {
	// position，缺省設成0
	private byte startPosition;
	
	/**
	 * 構造函數
	 */
	public GetFriendOnlinePacket() {
	    super(QQ.QQ_CMD_GET_FRIEND_ONLINE, true);
	    startPosition = QQ.QQ_FRIEND_ONLINE_LIST_POSITION_START;
	}
	
    /**
     * @param buf
     * @param length
     * @throws PacketParseException
     */
    public GetFriendOnlinePacket(ByteBuffer buf, int length)
            throws PacketParseException {
        super(buf, length);
    }
    
    /* (non-Javadoc)
     * @see edu.tsinghua.lumaqq.qq.packets.OutPacket#putBody(java.nio.ByteBuffer)
     */
    protected void putBody(ByteBuffer buf) {
        buf.put((byte)0x2);
        buf.put(startPosition);
        buf.put((byte)0);
        buf.put((byte)0);
        buf.put((byte)0);        
    }
    
    /* (non-Javadoc)
     * @see edu.tsinghua.lumaqq.qq.packets.OutPacket#parseBody(java.nio.ByteBuffer)
     */
    protected void parseBody(ByteBuffer buf) throws PacketParseException {
        buf.get();
        startPosition = buf.get();
    }
	
	/**
	 * @return Returns the position.
	 */
	public byte getStartPosition() {
		return startPosition;
	}
	
	/**
	 * @param position The position to set.
	 */
	public void setStartPosition(byte position) {
		this.startPosition = position;
	}
}