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

public class BleUDP : MonoBehaviour
{
    public static BleUDP ins; //单例记录

    readonly string localIP = "127.0.0.1"; //本地IP
    readonly int myPort = 8001; //自身的注册端口
    readonly int targetPort = 8000; //发消息的目标端口
    Socket client; //UDP对象

    float noneMsgTime = 0; //多久没收到字节消息了
    Queue<byte[]> byteQueue = new Queue<byte[]>(); //接收信息的线程把字节信息放这里
    Queue<byte[]> byteMainQueue = new Queue<byte[]>(); //主线程从byteQueue中取出数据后放在这里，供主线程update使用

    public Action OnConnected;
    public Action OnConnectionFailed;
    public Action<byte[]> OnCharacteristicChanged;
    public Action OnScanEnded;

    [NonSerialized] public BluetoothStatusEnum bluetoothStatusEnum = BluetoothStatusEnum.Connect;

    void Awake()
    {
        if (ins)
        {
            Destroy(this.gameObject);
            return;
        }
        ins = this;
        DontDestroyOnLoad(this.gameObject);
    }

    bool _inited;
    void Init() 
    {
        if (_inited) return;
        _inited = true;

        client = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
        client.Bind(new IPEndPoint(IPAddress.Parse(localIP), myPort));

        /*
         C# UDP Socket ReceiveFrom 远程主机强迫关闭了一个现有的连接。
        （经过反复研究，下述情况的原因终于搞清楚了，是"ICMP port unreachable"的问题，即：若向一个没有相应UDP监听端口的本机地址（比如127.0.0.1）发送UDP数据包，会回复ICMP port unreachable包，而这个包会被C#的UDP Socket ReceiveFrom函数得到，并报错为“远程主机强迫关闭了一个现有连接”！）
        （而为什么向存在的另一个ip（另一台主机）发送不会报错？因为防火墙！win10的防火墙把外部回复的ICMP port unreachable给屏蔽掉了。经实验，把防火墙关掉后，就会出现上述报错了。）
        （而为什么向一个不存在的ip地址发送不会报错？因为主机不存在，所以不会回复ICMP port unreachable）
         */
        //配置socket参数，避免ICMP包导致的异常
        uint IOC_IN = 0x80000000;
        uint IOC_VENDOR = 0x18000000;
        uint SIO_UDP_CONNRESET = IOC_IN | IOC_VENDOR | 12;
        client.IOControl((int)SIO_UDP_CONNRESET, new byte[] { Convert.ToByte(false) }, null);

        Thread threadReciveMsg = new Thread(ReciveMsg);
        threadReciveMsg.Start();
    }

    void OnDestroy()
    {
        if (ins == this) ins = null;
        if (client != null) client.Close();
    }

    void Update()
    {
        lock (byteQueue)
        {
            while (byteQueue.Count > 0)
            {
                byteMainQueue.Enqueue(byteQueue.Dequeue());
            }
        }
        if (bluetoothStatusEnum == BluetoothStatusEnum.Connecting)
        {
            if (noneMsgTime > 5)
            {
                bluetoothStatusEnum = BluetoothStatusEnum.ConnectFail;
                EmitOnConnectionFailed();
                return;
            }
            else if (byteMainQueue.Count > 0)
            {
                bluetoothStatusEnum = BluetoothStatusEnum.ConnectSuccess;
                EmitOnConnected();
            }
        }
        else if (bluetoothStatusEnum == BluetoothStatusEnum.ConnectSuccess)
        {
            if (noneMsgTime > 5)
            {
                bluetoothStatusEnum = BluetoothStatusEnum.ConnectFail;
                EmitOnConnectionFailed();
            }
        }
        else
        {
            byteMainQueue.Clear();
            return;
        }
        if (byteMainQueue.Count == 0)
        {
            noneMsgTime += Time.deltaTime;
            return;
        }
        noneMsgTime = 0;
        while (byteMainQueue.Count > 0)
        {
            EmitOnCharacteristicChanged(byteMainQueue.Dequeue());
        }
    }

    public void SendMsg(string data)
    {
        Debug.LogWarning("sendMsgToBle: " + data);
        EndPoint point = new IPEndPoint(IPAddress.Parse(localIP), targetPort);
        client.SendTo(Encoding.UTF8.GetBytes(data), point);
    }

    void ReciveMsg()
    {
        while (true)
        {
            EndPoint point = new IPEndPoint(IPAddress.Any, 0);
            byte[] buffer = new byte[1024];
            int length = client.ReceiveFrom(buffer, ref point);
            if (!point.ToString().EndsWith(targetPort.ToString())) continue;
            if (length <= 0) continue;
            byte[] bytes = new byte[length];
            Array.Copy(buffer, bytes, length);
            lock (byteQueue)
            {
                byteQueue.Enqueue(bytes);
            }
        }
    }

    public void ScanNearbyDevices()
    {
        EmitOnScanEnded();
    }

    public void Connect()
    {
        Init();
        noneMsgTime = 0;
        bluetoothStatusEnum = BluetoothStatusEnum.Connecting;
        SendMsg("M");
    }

    public void Disconnect()
    {
        bluetoothStatusEnum = BluetoothStatusEnum.Connect;
    }

    void EmitOnConnected()
    {
        try
        {
            OnConnected?.Invoke();
        }
        catch (Exception) { }
    }

    void EmitOnConnectionFailed()
    {
        try
        {
            OnConnectionFailed?.Invoke();
        }
        catch (Exception) { }
    }

    void EmitOnCharacteristicChanged(byte[] bytes)
    {
        try
        {
            OnCharacteristicChanged?.Invoke(bytes);
        }
        catch (Exception) { }
    }

    void EmitOnScanEnded()
    {
        try
        {
            OnScanEnded?.Invoke();
        }
        catch (Exception) { }
    }
}