using NetMQ;
using NetMQ.Sockets;
using Newtonsoft.Json;
using System;
using System.Collections.Concurrent;
using System.Diagnostics;
using System.Text;
using System.Threading.Tasks;

namespace SHH.CameraDashboard.Services;

/// <summary>
/// [Dashboard端] 指令控制服务
/// 职责：双向通信通道。接收 Service 心跳/响应，向 Service 发送控制指令。
/// 核心模式：ROUTER (Dashboard) <--> DEALER (Service)
/// </summary>
public class CommandServer : IDisposable
{
    // 单例模式
    public static CommandServer Instance { get; } = new CommandServer();

    // 事件：收到消息时触发 (ServiceId, MessageContent)
    public event Action<string, string>? OnMessageReceived;

    private RouterSocket? _routerSocket;
    private NetMQPoller? _poller;

    // 【关键新增】发送队列：用于解决跨线程发送的安全问题
    // UI线程 -> Enqueue -> Poller线程 -> Socket.Send
    private NetMQQueue<CommandPacket>? _sendQueue;

    public int ListenPort { get; private set; }
    public bool IsRunning => _poller != null && _poller.IsRunning;

    // 在线设备表 (可选，用于记录谁在线)
    // Key: ServiceId (Identity字符串)
    private readonly ConcurrentDictionary<string, DateTime> _onlineClients = new();

    private CommandServer() { }

    public void Start(int port)
    {
        ListenPort = port;
        if (IsRunning) return;

        try
        {
            // 1. 初始化 Router Socket
            _routerSocket = new RouterSocket();
            _routerSocket.Bind($"tcp://*:{ListenPort}");
            _routerSocket.ReceiveReady += OnSocketReady;

            // 2. 初始化发送队列
            _sendQueue = new NetMQQueue<CommandPacket>();
            _sendQueue.ReceiveReady += OnQueueReady;

            // 3. 启动 Poller (同时监听 Socket 接收 和 队列发送)
            _poller = new NetMQPoller { _routerSocket, _sendQueue };

            // RunAsync 会自动开启后台线程
            _poller.RunAsync();

            Console.WriteLine($"[Dashboard] 指令服务启动，监听: tcp://*:{ListenPort}");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"[Dashboard] 指令端口绑定失败: {ex.Message}");
            throw; // 必须抛出，让 App 感知
        }
    }

    /// <summary>
    /// 处理来自 Service 的网络消息 (运行在 Poller 线程)
    /// </summary>
    private void OnSocketReady(object? sender, NetMQSocketEventArgs e)
    {
        try
        {
            // 1. 读取身份帧 (Identity)
            // 只要 Service 端 DealerSocket 设置了 Identity，这里收到就是那个 ID
            var identityBytes = e.Socket.ReceiveFrameBytes();
            string serviceId = Encoding.UTF8.GetString(identityBytes);

            // 2. 读取内容帧 (假设 Dealer 直接发内容，中间无空帧)
            // 如果你使用了 REQ/REP 模式，中间可能会有空帧，需注意兼容
            string message = e.Socket.ReceiveFrameString();

            // 3. 简单的心跳保活逻辑
            _onlineClients[serviceId] = DateTime.Now;

            // 4. 触发业务事件
            // 注意：这依然在 Poller 线程，UI 处理时需 Invoke
            Console.WriteLine($"[指令] From {serviceId}: {message}");
            OnMessageReceived?.Invoke(serviceId, message);
        }
        catch (Exception ex)
        {
            Debug.WriteLine($"[Command Receive Error] {ex.Message}");
        }
    }

    /// <summary>
    /// 处理发送队列 (运行在 Poller 线程)
    /// </summary>
    private void OnQueueReady(object? sender, NetMQQueueEventArgs<CommandPacket> e)
    {
        try
        {
            if (_routerSocket == null) return;

            // 从队列取出一个包
            if (e.Queue.TryDequeue(out var packet, TimeSpan.Zero))
            {
                // Router 发送标准三步走：
                // 1. 发送目标 Identity (More = true)
                // 2. 发送空帧 (可选，取决于协议约定，Router-Dealer 直连通常不需要空帧)
                // 3. 发送数据 (More = false)

                // 这里我们采用最简协议：[Identity][Data]
                _routerSocket.SendMoreFrame(packet.TargetId)
                             .SendFrame(packet.JsonData);

                Console.WriteLine($"[指令] To {packet.TargetId}: {packet.JsonData}");
            }
        }
        catch (Exception ex)
        {
            Debug.WriteLine($"[Command Send Error] {ex.Message}");
        }
    }

    /// <summary>
    /// 发送指令 (线程安全，可由 UI 线程调用)
    /// </summary>
    public void SendCommand(string targetServiceId, object commandData)
    {
        if (_sendQueue == null) return;

        var json = JsonConvert.SerializeObject(commandData);

        // ★★★ 核心修复：不直接操作 Socket，而是入队 ★★★
        _sendQueue.Enqueue(new CommandPacket
        {
            TargetId = targetServiceId,
            JsonData = json
        });
    }

    public void Dispose()
    {
        _poller?.Stop();
        _poller?.Dispose();
        _routerSocket?.Dispose();
        _sendQueue?.Dispose();

        _poller = null;
        _routerSocket = null;
        _sendQueue = null;
    }

    // 内部数据包结构
    private class CommandPacket
    {
        public string TargetId { get; set; } = "";
        public string JsonData { get; set; } = "";
    }
}