using OpenCvSharp;

namespace SHH.CameraSdk;

/// <summary>
/// [标准动作环境] 图像预处理集群
/// 职责：透明拦截，计算缩放图挂载到 TargetMat 注入 SmartFrame，然后提交给全局中心
/// 特性：
/// 1. 设备分片：基于 DeviceId 哈希路由，保证单设备帧顺序严格一致
/// 2. 零内存拷贝：直接操作 SmartFrame 引用，仅在生成新 TargetMat 时申请内存
/// 3. 闭环流转：处理完成后自动投递到 GlobalProcessingCenter
/// </summary>
/// <summary>
/// 职责：透明拦截，计算缩放图挂载到 TargetMat，然后提交给全局中心
/// </summary>
public class ImageScaleCluster : IFrameProcessor
{
    private readonly List<ProcessingWorker> _workers = new();
    private readonly int _workerCount;

    public ImageScaleCluster(int workerCount = 4)
    {
        _workerCount = workerCount;
        for (int i = 0; i < workerCount; i++)
        {
            _workers.Add(new ProcessingWorker(i));
        }
        Console.WriteLine($"[ScaleCluster] 缩放服务已就绪 (Worker: {_workerCount})");
    }

    public void Enqueue(long deviceId, SmartFrame frame, FrameDecision decision)
    {
        // 1. 增加引用计数：跨线程持有
        frame.AddRef();

        // 2. 哈希分片路由：保证保序
        int index = (int)(Math.Abs(deviceId) % _workerCount);
        _workers[index].Post(deviceId, frame, decision);
    }

    public void Dispose() => _workers.ForEach(w => w.Dispose());
}

internal class ProcessingWorker : IDisposable
{
    private readonly BlockingCollection<(long DeviceId, SmartFrame Frame, FrameDecision Decision)> _queue = new(100);
    private readonly Task _thread;
    private readonly CancellationTokenSource _cts = new();

    public ProcessingWorker(int id)
    {
        _thread = Task.Factory.StartNew(ProcessLoop, TaskCreationOptions.LongRunning);
    }

    public void Post(long did, SmartFrame frame, FrameDecision decision)
    {
        if (!_queue.TryAdd((did, frame, decision)))
        {
            // 背压丢弃
            frame.Dispose();
        }
    }

    private void ProcessLoop()
    {
        foreach (var item in _queue.GetConsumingEnumerable(_cts.Token))
        {
            using (var frame = item.Frame)
            {
                try
                {
                    // -------------------------------------------------
                    // 核心动作：缩放逻辑
                    // -------------------------------------------------
                    int targetW = 704;
                    int targetH = 576;

                    // 仅当原图大于目标时才缩放
                    if (frame.InternalMat.Width > targetW)
                    {
                        Mat targetMat = new Mat();
                        Cv2.Resize(frame.InternalMat, targetMat, new Size(targetW, targetH), 0, 0, InterpolationFlags.Linear);

                        // [关键] 挂载到 SmartFrame 的衍生属性中
                        // 标记为 Shrink (缩小)
                        frame.AttachTarget(targetMat, FrameScaleType.Shrink);
                    }

                    // -------------------------------------------------
                    // 交付下一站：GlobalProcessingCenter
                    // 消费端对此无感知，它收到的是同一个 frame 对象
                    // -------------------------------------------------
                    GlobalProcessingCenter.Submit(item.DeviceId, frame, item.Decision);
                }
                catch (Exception ex)
                {
                    Console.WriteLine($"[ScaleWorker] 异常: {ex.Message}");
                    // 即使处理失败，也要尝试把原图发出去，保证画面不断
                    GlobalProcessingCenter.Submit(item.DeviceId, frame, item.Decision);
                }
            }
        }
    }

    public void Dispose()
    {
        _cts.Cancel();
        _queue.CompleteAdding();
        while (_queue.TryTake(out var item)) item.Frame.Dispose();
        _queue.Dispose();
        _cts.Dispose();
    }
}