import java.awt.*;
import java.net.*;
import java.io.*;
import java.util.*;
import javax.swing.*;

/**
 * Description:該類用于網絡通信，它包含了MulticastSocket實例和
 * DatagramSocket實例,分別實現廣播和私聊功能
 *
 * <br/>Copyright (C), 2008-2010, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee kongyeeku@163.com
 * @version  1.0
 */
//聊天交換信息的工具類
public class ComUtil
{
	//使用常量作為本程序的多點廣播IP地址
	private static final String BROADCAST_IP
		= "230.0.0.1";
	//使用常量作為本程序的多點廣播目的的端口
	//DatagramSocket所用的的端口為該端口-1。
	public static final int BROADCAST_PORT = 30000;
	//定義每個數據報的最大大小為4K
	private static final int DATA_LEN = 4096;
	
	//定義本程序的MulticastSocket實例
	private MulticastSocket socket = null;
	//定義本程序私聊的Socket實例
	private DatagramSocket singleSocket = null;
	//定義廣播的IP地址
	private InetAddress broadcastAddress = null;
	//定義接收網絡數據的字節數組
	byte[] inBuff = new byte[DATA_LEN];
	//以指定字節數組創建準備接受數據的DatagramPacket對象
	private DatagramPacket inPacket = 
		new DatagramPacket(inBuff , inBuff.length);
	//定義一個用于發送的DatagramPacket對象
	private DatagramPacket outPacket = null;
	
	//聊天的主界面
	private LanChat lanTalk;
	//構造器，初始化資源
	public ComUtil(LanChat lanTalk)throws IOException , InterruptedException
	{
		this.lanTalk = lanTalk;
		//創建用于發送、接收數據的MulticastSocket對象
		//因為該MulticastSocket對象需要接收，所以有指定端口
		socket = new MulticastSocket(BROADCAST_PORT);
		//創建私聊用的DatagramSocket對象
		singleSocket = new DatagramSocket(BROADCAST_PORT + 1);
		broadcastAddress = InetAddress.getByName(BROADCAST_IP);
		//將該socket加入指定的多點廣播地址
		socket.joinGroup(broadcastAddress);
		//設置本MulticastSocket發送的數據報被回送到自身
		socket.setLoopbackMode(false);
		//初始化發送用的DatagramSocket，它包含一個長度為0的字節數組
		outPacket = new DatagramPacket(new byte[0] , 0 ,
			broadcastAddress , BROADCAST_PORT);
		//啟動兩個讀取網絡數據的線程
		new ReadBroad().start();
 		Thread.sleep(1);
		new ReadSingle().start();
	}
	//廣播消息的工具方法
	public void broadCast(String msg)
	{
		try
		{
			//將msg字符串轉換字節數組
			byte[] buff = msg.getBytes();
			//設置發送用的DatagramPacket里的字節數據
			outPacket.setData(buff);
			//發送數據報
			socket.send(outPacket);
		}
		//捕捉異常
		catch (IOException ex)
		{
			ex.printStackTrace();
			if (socket != null)
			{
				//關閉該Socket對象
				socket.close();
			}
			JOptionPane.showMessageDialog(null, 
				"發送信息異常，請確認30000端口空閑，且網絡連接正常！"
				, "網絡異常", JOptionPane.ERROR_MESSAGE);
			System.exit(1);
		}
	}
	//定義向單獨用戶發送消息的方法
	public void sendSingle(String msg , SocketAddress dest)
	{
		try
		{
			//將msg字符串轉換字節數組
			byte[] buff = msg.getBytes();
			DatagramPacket packet = new DatagramPacket(
				buff , buff.length , dest);
			singleSocket.send(packet);
		}
		//捕捉異常
		catch (IOException ex)
		{
			ex.printStackTrace();
			if (singleSocket != null)
			{
				//關閉該Socket對象
				singleSocket.close();
			}
			JOptionPane.showMessageDialog(null, 
				"發送信息異常，請確認30001端口空閑，且網絡連接正常！"
				, "網絡異常", JOptionPane.ERROR_MESSAGE);
			System.exit(1);
		}
	}
	//不斷從DatagramSocket中讀取數據的線程
	class ReadSingle extends Thread
	{
		//定義接收網絡數據的字節數組
		byte[] singleBuff = new byte[DATA_LEN];
		private DatagramPacket singlePacket = 
			new DatagramPacket(singleBuff , singleBuff.length);
		public void run()
		{
			while (true)
			{
				try
				{
					//讀取Socket中的數據，讀到的數據放在inPacket所封裝的字節數組里。
					singleSocket.receive(singlePacket);
					//處理讀到的信息
					lanTalk.processMsg(singlePacket , true);
				}
				//捕捉異常
				catch (IOException ex)
				{
					ex.printStackTrace();
					if (singleSocket != null)
					{
						//關閉該Socket對象
						singleSocket.close();
					}
					JOptionPane.showMessageDialog(null,
						"接收信息異常，請確認30001端口空閑，且網絡連接正常！"
						, "網絡異常", JOptionPane.ERROR_MESSAGE);
					System.exit(1);
				}				
			}
		}
	}
	//持續讀取MulticastSocket的線程
	class ReadBroad extends Thread
	{
		public void run()
		{
			while (true)
			{
				try
				{
					//讀取Socket中的數據，讀到的數據放在inPacket所封裝的字節數組里。
					socket.receive(inPacket);
					//打印輸出從socket中讀取的內容
					String msg = new String(inBuff , 0 , inPacket.getLength());
					//讀到的內容是在線信息
					if (msg.startsWith(YeekuProtocol.PRESENCE)
						&& msg.endsWith(YeekuProtocol.PRESENCE))
					{
						String userMsg = msg.substring(2 , msg.length() - 2);
						String[] userInfo = userMsg.split(YeekuProtocol.SPLITTER);
						UserInfo user = new UserInfo(userInfo[1] , userInfo[0] , 
							inPacket.getSocketAddress(), 0);
						//控制是否需要添加該用戶的旗標
						boolean addFlag = true;
						ArrayList<Integer> delList = new ArrayList<Integer>();
						//遍歷系統中已有的所有用戶,該循環必須循環完成
						for (int i = 1 ; i < lanTalk.getUserNum() ; i++ )
						{
							UserInfo current = lanTalk.getUser(i);
							//將所有用戶失去聯系的次數加1
							current.setLost(current.getLost() + 1);
							//如果該信息由指定用戶發送過來
							if (current.equals(user))
							{
								current.setLost(0);
								//設置該用戶無需添加
								addFlag = false;
							}
							if (current.getLost() > 2)
							{
								delList.add(i);
							}
						}
						//刪除delList中的所有索引對應的用戶
						for (int i = 0; i < delList.size() ; i++)
						{
							lanTalk.removeUser(delList.get(i));
						}
						if (addFlag)
						{
							//添加新用戶
							lanTalk.addUser(user);
						}						
					}
					//讀到的內容是公聊信息
					else
					{
						//處理讀到的信息
						lanTalk.processMsg(inPacket , false);
					}
				}
				//捕捉異常
				catch (IOException ex)
				{
					ex.printStackTrace();
					if (socket != null)
					{
						//關閉該Socket對象
						socket.close();
					}
					JOptionPane.showMessageDialog(null, 
						"接收信息異常，請確認30000端口空閑，且網絡連接正常！"
						, "網絡異常", JOptionPane.ERROR_MESSAGE);
					System.exit(1);
				}
			}
		}
	}
}