// TcpManager.cs
using IPCLib;
using System;
using System.IO;
using System.Net.Sockets;
using System.Text;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;


// TcpManager.cs - 修正版
// TcpManager.cs - 完整修复版

using System.Collections.Concurrent;

public class TcpManager : IDisposable
{
    private TcpListener _listener;
    private TcpClient _client;
    private NetworkStream _stream;
    private CancellationTokenSource _cts = new CancellationTokenSource();
    private Task _receiveTask;
    private Task _acceptTask;
    private System.Threading.Timer _heartbeatTimer;
    private System.Threading.Timer _timeoutCheckTimer;

    private long _sequenceId = 0;
    private DateTime _lastHeartbeatTime = DateTime.Now;
    private int _heartbeatTimeoutSeconds = 5;
    private bool _isConnected = false;
    private readonly object _lockObj = new object();  // 线程锁

    public bool IsServer { get; set; }
    public int HeartbeatInterval { get; set; } = 1000;
    public string LocalIdentity { get; set; } = "App";
    public int MaxReconnectAttempts { get; set; } = 5;  // 最大重连次数
    public int ReconnectDelay { get; set; } = 2000;     // 重连间隔

    // 事件
    public event Action<HeartbeatPacket> PacketReceived;
    public event Action Connected;
    public event Action<string> Disconnected;
    public event Action<string, Exception> ErrorOccurred;  // 添加 Exception 参数

    private readonly ConcurrentQueue<string> _dataQueue = new ConcurrentQueue<string>();

    /// <summary>
    /// 服务端启动监听
    /// </summary>
    public async Task StartServerAsync(int port)
    {
        IsServer = true;

        try
        {
            // ✅ 设置 SO_REUSEADDR，允许端口重用
            _listener = new TcpListener(System.Net.IPAddress.Loopback, port);
            _listener.Server.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
            _listener.Start();

            Log($"服务端已启动，监听端口：{port}");
            _acceptTask = AcceptClientAsync();
            await Task.CompletedTask;
        }
        catch (SocketException ex)
        {
            HandleSocketError("启动监听失败", ex);
            throw;
        }
        catch (Exception ex)
        {
            ErrorOccurred?.Invoke("启动监听失败", ex);
            throw;
        }
    }

    /// <summary>
    /// 后台接受客户端连接
    /// </summary>
    private async Task AcceptClientAsync()
    {
        try
        {
            Log("等待客户端连接...");
            _client = await _listener.AcceptTcpClientAsync(_cts.Token);

            // ✅ 配置 Socket 选项
            ConfigureSocket(_client);

            _stream = _client.GetStream();
            _lastHeartbeatTime = DateTime.Now;
            _isConnected = true;

            Log("客户端已连接");
            Connected?.Invoke();

            _receiveTask = ReceiveLoopAsync();
            StartHeartbeatTimer();
            StartTimeoutCheckTimer();
        }
        catch (OperationCanceledException)
        {
            Log("接受连接已取消");
        }
        catch (SocketException ex)
        {
            HandleSocketError("接受连接失败", ex);
        }
        catch (Exception ex)
        {
            ErrorOccurred?.Invoke("接受连接失败", ex);
        }
    }

    private void StartHeartbeatTimer()
    {
        _heartbeatTimer = new System.Threading.Timer(async _ =>
        {
            await SendHeartbeatAsync();
        }, null, 0, HeartbeatInterval);
    }

    /// <summary>
    /// ✅ 启动超时检测定时器（核心修复）
    /// </summary>
    private void StartTimeoutCheckTimer()
    {
        _timeoutCheckTimer = new System.Threading.Timer(_ =>
        {
            CheckConnectionTimeout();
        }, null, HeartbeatInterval, HeartbeatInterval);
    }

    /// <summary>
    /// 客户端启动连接（带重连）
    /// </summary>
    public async Task StartClientAsync(string host, int port)
    {
        IsServer = false;
        int reconnectCount = 0;

        while (!_cts.Token.IsCancellationRequested)
        {
            try
            {
                Log($"尝试连接 {host}:{port} (尝试 {reconnectCount + 1}/{MaxReconnectAttempts})...");

                _client = new TcpClient();
                _client.ReceiveTimeout = 5000;   // ✅ 设置接收超时
                _client.SendTimeout = 5000;      // ✅ 设置发送超时

                await _client.ConnectAsync(host, port, _cts.Token);

                ConfigureSocket(_client);

                _stream = _client.GetStream();
                _lastHeartbeatTime = DateTime.Now;
                _isConnected = true;

                Log($"已连接到服务端 {host}:{port}");
                Connected?.Invoke();

                _receiveTask = ReceiveLoopAsync();
                StartHeartbeatTimer();
                StartTimeoutCheckTimer();
                return;  // 连接成功，退出重连循环
            }
            catch (SocketException ex)
            {
                reconnectCount++;
                HandleSocketError($"连接失败 (尝试 {reconnectCount}/{MaxReconnectAttempts})", ex);

                if (reconnectCount >= MaxReconnectAttempts)
                {
                    ErrorOccurred?.Invoke($"达到最大重连次数 {MaxReconnectAttempts}", ex);
                    await HandleDisconnect($"达到最大重连次数：{ex.Message}");
                    return;
                }

                Log($"{ReconnectDelay}ms 后重试...");
                await Task.Delay(ReconnectDelay, _cts.Token);
            }
            catch (OperationCanceledException)
            {
                Log("连接已取消");
                return;
            }
            catch (Exception ex)
            {
                reconnectCount++;
                ErrorOccurred?.Invoke($"连接异常 (尝试 {reconnectCount}/{MaxReconnectAttempts})", ex);

                if (reconnectCount >= MaxReconnectAttempts)
                {
                    await HandleDisconnect($"连接异常：{ex.Message}");
                    return;
                }

                await Task.Delay(ReconnectDelay, _cts.Token);
            }
        }
    }

    /// <summary>
    /// ✅ 配置 Socket 选项
    /// </summary>
    private void ConfigureSocket(TcpClient client)
    {
        try
        {
            // 启用 KeepAlive
            client.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.KeepAlive, true);

            // 禁用 Nagle 算法（减少延迟）
            client.NoDelay = true;

            // 设置缓冲区大小
            client.ReceiveBufferSize = 8192;
            client.SendBufferSize = 8192;
        }
        catch (Exception ex)
        {
            Log($"配置 Socket 失败：{ex.Message}");
        }
    }

    /// <summary>
    /// ✅ 处理 Socket 错误
    /// </summary>
    private void HandleSocketError(string context, SocketException ex)
    {
        string errorMessage = $"{context} - Socket 错误 {ex.SocketErrorCode} ({ex.NativeErrorCode}): {ex.Message}";
        Log($"❌ {errorMessage}");
        ErrorOccurred?.Invoke(errorMessage, ex);

        // 根据错误码采取不同措施
        switch (ex.SocketErrorCode)
        {
            case SocketError.ConnectionReset:      // 10054
            case SocketError.ConnectionAborted:    // 10053
            case SocketError.Shutdown:             // 10058
                Log("连接被对端关闭，触发断开事件");
                Task.Run(() => HandleDisconnect("连接被对端关闭"));
                break;

            case SocketError.AddressAlreadyInUse:  // 10048
                Log("端口被占用，尝试使用其他端口");
                break;

            case SocketError.ConnectionRefused:    // 10061
                Log("连接被拒绝，检查服务端是否运行");
                break;

            case SocketError.TimedOut:             // 10060
                Log("连接超时");
                break;

            default:
                Log($"未处理的 Socket 错误：{ex.SocketErrorCode}");
                break;
        }
    }

    /// <summary>
    /// 检查连接是否超时
    /// </summary>
    private void CheckConnectionTimeout()
    {
        try
        {
            lock (_lockObj)
            {
                var timeSinceLastHeartbeat = DateTime.Now - _lastHeartbeatTime;

                if (timeSinceLastHeartbeat.TotalSeconds > _heartbeatTimeoutSeconds)
                {
                    Log($"⚠️ 心跳超时！最后心跳：{timeSinceLastHeartbeat.TotalSeconds:F1} 秒前");
                    Task.Run(() => HandleDisconnect("心跳超时"));
                }
            }
        }
        catch (Exception ex)
        {
            Log($"超时检测错误：{ex.Message}");
        }
    }

    /// <summary>
    /// 处理断开连接
    /// </summary>
    private async Task HandleDisconnect(string reason)
    {
        lock (_lockObj)
        {
            if (!_isConnected) return;  // 避免重复触发
            _isConnected = false;
        }

        Log($"处理断开：{reason}");
        Disconnected?.Invoke(reason);
        await CleanupAsync();
    }

    /// <summary>
    /// 接收消息循环（增强错误处理）
    /// </summary>
    private async Task ReceiveLoopAsync()
    {
        if (_stream == null) return;
        var buffer = new byte[4096];
        var sb = new StringBuilder();

        try
        {
            while (!_cts.Token.IsCancellationRequested && _isConnected)
            {
                var readCts = CancellationTokenSource.CreateLinkedTokenSource(_cts.Token);
                readCts.CancelAfter(5000);

                try
                {
                    int read = await _stream.ReadAsync(buffer, 0, buffer.Length, readCts.Token);

                    if (read == 0)
                    {
                        Log("连接已关闭（Read 返回 0）");
                        await HandleDisconnect("连接已关闭");
                        break;
                    }

                    lock (_lockObj) { _lastHeartbeatTime = DateTime.Now; }

                    string text = Encoding.UTF8.GetString(buffer, 0, read);
                    sb.Append(text);

                    string content = sb.ToString();
                    int idx;
                    while ((idx = content.IndexOf('\n')) >= 0)
                    {
                        string line = content.Substring(0, idx).Trim('\r');
                        if (!string.IsNullOrEmpty(line))
                        {
                            try
                            {
                                var packet = JsonSerializer.Deserialize<HeartbeatPacket>(line);
                                if(packet !=null)
                                    PacketReceived?.Invoke(packet);
                            }
                            catch (JsonException ex)
                            {
                                Log($"JSON 解析错误：{ex.Message}");
                            }
                        }
                        content = content.Substring(idx + 1);
                    }
                    sb.Clear();
                    sb.Append(content);
                }
                catch (OperationCanceledException)
                {
                    continue;
                }
                catch (IOException ex) when (ex.InnerException is SocketException sockEx)
                {
                    HandleSocketError("接收数据时 Socket 错误", sockEx);
                    await HandleDisconnect($"Socket 错误：{sockEx.SocketErrorCode}");
                    break;
                }
                catch (IOException ex)
                {
                    Log($"IO 错误：{ex.Message}");
                    await HandleDisconnect($"IO 错误：{ex.Message}");
                    break;
                }
                catch (ObjectDisposedException)
                {
                    Log("Stream 已释放");
                    await HandleDisconnect("Stream 已释放");
                    break;
                }
            }
        }
        catch (Exception ex)
        {
            Log($"接收循环错误：{ex.Message}");
            await HandleDisconnect($"接收错误：{ex.Message}");
        }
    }

    /// <summary>
    /// 发送心跳（增强错误处理）
    /// </summary>
    private async Task SendHeartbeatAsync()
    {
        if (!_isConnected || _stream == null || _client?.Connected != true) return;

        string payload = "";
        if (_dataQueue.TryDequeue(out var data))
        {
            payload = data;
        }

        var packet = new HeartbeatPacket
        {
            Source = LocalIdentity,
            Timestamp = DateTime.Now.Ticks,
            SequenceId = Interlocked.Increment(ref _sequenceId),
            Payload = payload
        };

        try
        {
            string json = JsonSerializer.Serialize(packet) + "\n";
            byte[] dataBytes = Encoding.UTF8.GetBytes(json);
            await _stream.WriteAsync(dataBytes, 0, dataBytes.Length, _cts.Token);
            await _stream.FlushAsync(_cts.Token);
        }
        catch (IOException ex) when (ex.InnerException is SocketException sockEx)
        {
            HandleSocketError("发送心跳时 Socket 错误", sockEx);
            await HandleDisconnect($"发送失败：{sockEx.SocketErrorCode}");
        }
        catch (ObjectDisposedException)
        {
            Log("Stream 已释放，无法发送");
            await HandleDisconnect("Stream 已释放");
        }
        catch (Exception ex)
        {
            Log($"发送失败：{ex.Message}");
            await HandleDisconnect($"发送失败：{ex.Message}");
        }
    }

    public void PushData(string jsonData)
    {
        if (!_isConnected)
        {
            Log("⚠️ 未连接，数据无法发送");
            return;
        }
        _dataQueue.Enqueue(jsonData);
    }

    private void Log(string msg) => System.Diagnostics.Debug.WriteLine($"[{LocalIdentity}] {msg}");

    private async Task CleanupAsync()
    {
        lock (_lockObj)
        {
            _isConnected = false;
        }

        _heartbeatTimer?.Dispose();
        _timeoutCheckTimer?.Dispose();

        try
        {
            _stream?.Dispose();
        }
        catch (Exception ex) { Log($"释放 Stream 失败：{ex.Message}"); }

        try
        {
            _client?.Dispose();
        }
        catch (Exception ex) { Log($"释放 Client 失败：{ex.Message}"); }

        try
        {
            _listener?.Stop();
        }
        catch (Exception ex) { Log($"停止 Listener 失败：{ex.Message}"); }

        _cts.Cancel();
    }

    public void Dispose()
    {
        _cts.Cancel();
        CleanupAsync().Wait();
        _cts.Dispose();
    }
}