namespace BmsMonitor.App.Can;

public sealed class ControlCanReceiver : ICanReceiver
{
    private CancellationTokenSource? _cts;
    private Task? _receiveTask;
    private uint _deviceIndex;
    private uint _channelIndex;

    public bool IsOpen { get; private set; }
    public event EventHandler<CanFrame>? FrameReceived;
    public event EventHandler<string>? ReceiveError;

    public void Open(uint deviceIndex, uint channelIndex, CanBaudRate baudRate = CanBaudRate.Kbps250)
    {
        if (IsOpen) return;

        _deviceIndex = deviceIndex;
        _channelIndex = channelIndex;
        if (ControlCanNative.VCI_OpenDevice(ControlCanNative.VciUsbCan2, deviceIndex, 0) != ControlCanNative.StatusOk)
            throw new InvalidOperationException("打开 USBCAN-II 失败，请检查驱动、设备索引及 ControlCAN.dll。");

        var (timing0, timing1) = baudRate.ToTiming();
        var config = new ControlCanNative.VciInitConfig
        {
            AccCode = 0,
            AccMask = 0xFFFFFFFF,
            Filter = 1,
            Timing0 = timing0,
            Timing1 = timing1,
            Mode = 1 // 硬件只听模式：仅接收，不发送 ACK
        };

        var initResult = ControlCanNative.VCI_InitCAN(ControlCanNative.VciUsbCan2, deviceIndex, channelIndex, ref config);
        if (initResult != ControlCanNative.StatusOk)
        {
            ControlCanNative.VCI_CloseDevice(ControlCanNative.VciUsbCan2, deviceIndex);
            throw new InvalidOperationException($"VCI_InitCAN 失败（返回 {initResult}，通道 CAN{channelIndex + 1}，{baudRate.ToDisplayText()}，只听模式）。");
        }

        var startResult = ControlCanNative.VCI_StartCAN(ControlCanNative.VciUsbCan2, deviceIndex, channelIndex);
        if (startResult != ControlCanNative.StatusOk)
        {
            ControlCanNative.VCI_ResetCAN(ControlCanNative.VciUsbCan2, deviceIndex, channelIndex);
            ControlCanNative.VCI_CloseDevice(ControlCanNative.VciUsbCan2, deviceIndex);
            throw new InvalidOperationException($"VCI_StartCAN 失败（返回 {startResult}，通道 CAN{channelIndex + 1}）。");
        }

        IsOpen = true;
        _cts = new CancellationTokenSource();
        _receiveTask = Task.Run(() => ReceiveLoop(_cts.Token));
    }

    private void ReceiveLoop(CancellationToken token)
    {
        var buffer = Enumerable.Range(0, 100).Select(_ => new ControlCanNative.VciCanObj
        {
            Data = new byte[8], Reserved = new byte[3]
        }).ToArray();

        try
        {
            while (!token.IsCancellationRequested)
            {
                var count = ControlCanNative.VCI_Receive(ControlCanNative.VciUsbCan2, _deviceIndex, _channelIndex,
                    buffer, (uint)buffer.Length, 50);
                if (count == 0 || count == uint.MaxValue) continue;

                for (var i = 0; i < Math.Min(count, (uint)buffer.Length); i++)
                {
                    var item = buffer[i];
                    if (item.RemoteFlag != 0) continue;
                    var length = Math.Min(item.DataLen, (byte)8);
                    FrameReceived?.Invoke(this, new CanFrame(item.Id, item.ExternFlag != 0,
                        item.Data.Take(length).ToArray(), DateTime.Now));
                }
            }
        }
        catch (Exception ex) when (!token.IsCancellationRequested)
        {
            ReceiveError?.Invoke(this, ex.Message);
        }
    }

    public void Close()
    {
        if (!IsOpen) return;
        _cts?.Cancel();
        _receiveTask?.Wait(300);
        ControlCanNative.VCI_ResetCAN(ControlCanNative.VciUsbCan2, _deviceIndex, _channelIndex);
        ControlCanNative.VCI_CloseDevice(ControlCanNative.VciUsbCan2, _deviceIndex);
        _cts?.Dispose();
        _cts = null;
        IsOpen = false;
    }

    public void Dispose() => Close();
}