using UnityEngine;
using System;
using System.Net;
using System.Net.Sockets;
using System.Collections;
using System.Text;
using System.Collections.Generic;

public class NetServer {

	//單例指令碼
	public static readonly NetServer Instance = new NetServer();
	//定義tcp伺服器
	private Socket server;
	private int maxClient = 10;
	//定義埠
	private int port = 35353;
	//使用者池
	private Stack<NetUserToken> pools;
	private NetServer()
	{
		//初始化socket
		server = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
		server.Bind(new IPEndPoint(IPAddress.Any, port));
	}

	//開啟伺服器
	public void Start()
	{
		server.Listen(maxClient);
		Debug.Log("Server OK!");
		//例項化客戶端的使用者池
		pools = new Stack<NetUserToken>(maxClient);
		for(int i = 0; i < maxClient; i++)
		{
			NetUserToken usertoken = new NetUserToken();
			pools.Push(usertoken);
		}
		//可以非同步接受客戶端, BeginAccept函式的第一個引數是回撥函式，當有客戶端連線的時候自動呼叫
		server.BeginAccept (AsyncAccept, null);
	}

	//回撥函式， 有客戶端連線的時候會自動呼叫此方法
	private void AsyncAccept(IAsyncResult result)
	{
		try {
			//結束監聽，同時獲取到客戶端
			Socket client = server.EndAccept(result);
			UnityEngine.Debug.Log("有客戶端連線");
			//來了一個客戶端
			NetUserToken userToken = pools.Pop();
			userToken.socket = client;
			//客戶端連線之後，可以接受客戶端訊息
			BeginReceive(userToken);

			//尾遞迴，再次監聽是否還有其他客戶端連入
			server.BeginAccept(AsyncAccept, null);
		} catch (Exception ex) {
			Debug.Log(ex.ToString());
		}
	}

	//非同步監聽訊息
	private void BeginReceive(NetUserToken userToken)
	{
		try {
			//非同步方法
			userToken.socket.BeginReceive(userToken.buffer, 0, userToken.buffer.Length, SocketFlags.None,
				EndReceive, userToken);
			string msg = Encoding.UTF8.GetString(userToken.buffer);
			Debug.Log(msg);
		} catch (Exception ex) {
			Debug.Log(ex.ToString());
		}
	}

	//監聽到訊息之後呼叫的函式
	private void EndReceive(IAsyncResult result)
	{
		try {
			//取出客戶端
			NetUserToken userToken = result.AsyncState as NetUserToken;
			//獲取訊息的長度
			int len = userToken.socket.EndReceive(result);
			if(len > 0)
			{ 
				byte[] data = new byte[len];
				Buffer.BlockCopy(userToken.buffer, 0, data, 0, len);
				//使用者接受訊息
				userToken.Receive(data);
				//尾遞迴，再次監聽客戶端訊息
				BeginReceive(userToken);
			}

		} catch (Exception ex) {
			Debug.Log(ex.ToString());
		}
	}

}