using Microsoft.Extensions.Hosting;
using NetMQ;
using NetMQ.Sockets;

namespace SHH.CameraService;

/// <summary>
/// NetMQ 发送工作者
/// 职责：从指定目标的 VideoDataChannel 读取 Payload，通过 ZeroMQ 发送出去
/// </summary>
public class NetMqSenderWorker : BackgroundService
{
    private readonly StreamTarget _target;

    // 构造函数注入特定的目标对象 (由 Program.cs 的工厂方法提供)
    public NetMqSenderWorker(StreamTarget target)
    {
        _target = target;
    }
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        // 增加重启保护
        while (!stoppingToken.IsCancellationRequested)
        {
            try
            {
                Console.WriteLine($"[NetMqSender] 连接至: {_target.Config.Endpoint}");

                using var clientSocket = new PublisherSocket();
                clientSocket.Options.SendHighWatermark = 1000;
                // 关键：增加 TCP 保活，防止防火墙静默断开长连接
                clientSocket.Options.TcpKeepalive = true;
                clientSocket.Options.TcpKeepaliveIdle = TimeSpan.FromSeconds(5);

                clientSocket.Connect(_target.Config.Endpoint);

                int frameCount = 0;

                // 使用更稳健的读取方式
                await foreach (var payload in _target.Channel.Reader.ReadAllAsync(stoppingToken))
                {
                    try
                    {
                        // 1. 构造消息 (内部执行了 MessagePack 序列化)
                        var msg = payload.ToNetMqMessage();

                        // 2. 发送
                        bool sent = clientSocket.TrySendMultipartMessage(msg);

                        if (!sent)
                        {
                            Console.WriteLine($"[NetMqSender] 发送缓冲区满，丢弃帧: {payload.CameraId}");
                            // ★ 如果没有发送成功，建议显式清理消息帧，防止内存滞留
                            msg.Clear();
                        }
                        else
                        {
                            frameCount++;
                            if (frameCount % 100 == 0)
                                Console.WriteLine($"[NetMqSender] 已搬运 100 帧至缓冲区.");
                        }
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine($"[NetMqSender] 内部循环异常: {ex.Message}");
                    }
                }
            }
            catch (OperationCanceledException) { break; }
            catch (Exception ex)
            {
                // ★★★ 核心改进：捕获异常并等待重试 ★★★
                // 防止因为一次内存溢出或网络波动导致整个 BackgroundService 永久停止
                Console.WriteLine($"[NetMqSender] 发生致命异常，5秒后尝试重建连接: {ex.Message}");
                await Task.Delay(5000, stoppingToken);
            }
            finally
            {
                // 确保每次循环退出（无论是异常还是正常）都清理环境
                NetMQConfig.Cleanup(false);
            }
        }
    }
}