#nullable enable
using System.Diagnostics;
using NewTek;
using NewTek.NDI;
using SharpDX.Direct3D11;
using T3.Core.Animation;
using T3.Core.DataTypes.DataSet;
using T3.Core.Utils;

namespace Lib.io.video;

[Guid("7567c3b0-9d91-40d2-899d-3a95b481d023")]
public sealed class NdiInput : Instance<NdiInput>, IStatusProvider, ICustomDropdownHolder
{
    [Output(Guid = "85F1AF38-074E-475D-94F5-F48079979509", DirtyFlagTrigger = DirtyFlagTrigger.Animated)]
    public readonly Slot<Texture2D?> Texture = new();

    public NdiInput()
    {
        InitializeNdi();

        // Note that this example does see local sources (new Finder(true))
        // This is for ease of testing, but normally is not needed in released products.
        _ndiInputFinder = new Finder(true);
        Texture.UpdateAction += Update;
    }

    private double _lastUpdateRunTime;

    private void Update(EvaluationContext context)
    {
        var reconnectTriggered = MathUtils.WasTriggered(TriggerReconnect.GetValue(context), ref _reconnect);
        if (reconnectTriggered)
        {
            TriggerReconnect.SetTypedInputValue(false);
        }

        _lastUpdateRunTime = Playback.RunTimeInSecs;
        if (SourceName.DirtyFlag.IsDirty || reconnectTriggered)
        {
            var sourceName = SourceName.GetValue(context);
            _textureMutex.WaitOne(Timeout.Infinite);
            DisposeTextures();
            if(sourceName != null)
                    Connect(sourceName);

            _textureMutex.ReleaseMutex();
        }

        _isProfiling = EnableProfiling.GetValue(context);

        _textureAction?.Invoke();
        _textureAction = null;
        Texture.Value = _lastTexture;
    }

    private void InitializeNdi()
    {
        // Not required, but "correct". (see the SDK documentation)
        if (_initialized)
            return;

        try
        {
            _initialized = NDIlib.initialize();
            if (_initialized)
                return;
        }
        catch (Exception e)
        {
            Log.Error("Failed to initialize NDIInput. One possible reason could be 'Processing.NDI.Lib.x64.dll' missing: " + e.Message);
            return;
        }

        // Cannot run NDI. Most likely because the CPU is not sufficient (see SDK documentation).
        // you can check this directly with a call to NDIlib.is_supported_CPU()
        // not sure why, but it's not going to run
        SetErrorMessage(!NDIlib.is_supported_CPU()
                            ? "CPU unsupported."
                            : "Cannot run NDI.");
    }

    private void SetErrorMessage(string message)
    {
        Log.Error(message, this);
        _lastStatusMessage = message;
    }

    private void SetAttentionMessage(string message)
    {
        Log.Warning(message, this);
        _lastStatusMessage = message;
    }

    /// <summary>
    ///  connect to an NDI source in our Dictionary by name
    /// </summary>
    // private void Connect(Source source)
    private void Connect(string sourceName)
    {
        // Increment the receiver Id, meaning we have a new source to work with. If
        // there's already another receiver thread running, the commands it has
        // sent to the UI won't be processed.
        var receiverId = Interlocked.Increment(ref _receiverId);

        Disconnect(); // just to be safe

        if (string.IsNullOrEmpty(sourceName))
            return;

        var sourceExists = _ndiInputFinder.Sources.Any(s => s.Name == sourceName);
        if (!sourceExists)
        {
            if (sourceName == "0")
            {
                SetAttentionMessage($"{PlaceholderText}");
            }
            else
            {
                SetErrorMessage($"NDI source {sourceName} not found");
            }
            return;
        }

        Log.Debug($"Connecting to {sourceName}...", this);

        var selectedSourceT = new NDIlib.source_t
                                  {
                                      p_ndi_name = UTF.StringToUtf8(sourceName)
                                  };

        var receiverDescription = new NDIlib.recv_create_v3_t
                                      {
                                          source_to_connect_to = selectedSourceT,
                                          color_format = NDIlib.recv_color_format_e.recv_color_format_BGRX_BGRA,
                                          bandwidth = NDIlib.recv_bandwidth_e.recv_bandwidth_highest,
                                          allow_video_fields = false, // let NDIlib deinterlace for us if needed  ?

                                          // The name of the NDI receiver to create. This is a NULL terminated UTF8 string and should be
                                          // the name of receive channel that you have. This is in many ways symetric with the name of
                                          // senders, so this might be "Channel 1" on your system.
                                          p_ndi_recv_name = UTF.StringToUtf8(sourceName)
                                      };

        // Create a new instance connected to this source
        _receiveInstancePtr = NDIlib.recv_create_v3(ref receiverDescription);

        // Free the memory we allocated with StringToUtf8
        Marshal.FreeHGlobal(selectedSourceT.p_ndi_name);
        Marshal.FreeHGlobal(receiverDescription.p_ndi_recv_name);

        Debug.Assert(_receiveInstancePtr != IntPtr.Zero, "Failed to create NDI receive instance.");

        if (_receiveInstancePtr == IntPtr.Zero)
            return;

        // Mark this source as being on program output for tally purposes (but not on preview)
        SetTallyIndicators(true, false);

        _receiveThread = new Thread(ReceiveThreadProc)
                             {
                                 IsBackground = true, Name = "NdiInputReceiver"
                             };
        
        _receiveThread.Start(receiverId);
    }

    private void Disconnect()
    {
        // in case we're connected, reset the tally indicators
        SetTallyIndicators(false, false);

        if (_receiveThread != null)
        {
            _exitThread = true;
            _receiveThread.Join(); // wait for it to end
        }

        _receiveThread = null;
        _exitThread = false;

        NDIlib.recv_destroy(_receiveInstancePtr);

        _receiveInstancePtr = IntPtr.Zero;
    }

    private void SetTallyIndicators(bool onProgram, bool onPreview)
    {
        // We need to have a receive instance
        if (_receiveInstancePtr == IntPtr.Zero)
            return;

        var tallyStateDescriptor = new NDIlib.tally_t
                                       {
                                           on_program = onProgram,
                                           on_preview = onPreview
                                       };

        if (_isProfiling)
            DebugDataRecording.KeepTraceData(this, "01-SetTallyIndicators", tallyStateDescriptor, ref _traceTallyChannel);

        NDIlib.recv_set_tally(_receiveInstancePtr, ref tallyStateDescriptor);
    }


    
    /// <summary>
    /// Receive thread runs though this loop until told to exit
    /// </summary>
    private void ReceiveThreadProc(object? param)
    {
        var currReceiverId = 0;
        
        if (param == null)
        {
            Log.Warning("NdiInput thread param is null?", this);
        }
        else
        {
            currReceiverId = (int)param;
        }

        // Here we keep track of the receiver Id used for this thread.

        if (_isProfiling)
            DebugDataRecording.KeepTraceData(this, "02-ReceiveThreadProc", currReceiverId, ref _traceReceiveThreadProc);

        while (!_exitThread && _receiveInstancePtr != IntPtr.Zero)
        {
            // The descriptors
            var videoFrame = new NDIlib.video_frame_v2_t();
            var audioFrame = new NDIlib.audio_frame_v2_t();
            var metadataFrame = new NDIlib.metadata_frame_t();

            var recvCaptureV2 = NDIlib.recv_capture_v2(_receiveInstancePtr, ref videoFrame, ref audioFrame, ref metadataFrame, 1000);

            if (_isProfiling)
                DebugDataRecording.KeepTraceData(this, "03-ReceiveThreadProc", recvCaptureV2, ref _traceReceive2ThreadProc);

            //Log.Debug("received frame " + recvCaptureV2 + " from NDI input.", this);
            switch (recvCaptureV2)
            {
                // No data
                case NDIlib.frame_type_e.frame_type_none:
                    break;

                // frame settings - check for extended functionality
                case NDIlib.frame_type_e.frame_type_status_change:
                    break;

                // Video data
                case NDIlib.frame_type_e.frame_type_video:

                    // if not enabled, just discard
                    // this can also occasionally happen when changing sources
                    if (!VideoEnabled || videoFrame.p_data == IntPtr.Zero)
                    {
                        // always free received frame
                        NDIlib.recv_free_video_v2(_receiveInstancePtr, ref videoFrame);
                        Log.Warning("NDI input not enabled, skipping frame.", this);
                        break;
                    }

                    if (Playback.RunTimeInSecs - _lastUpdateRunTime > 1 / 30f)
                    {
                        NDIlib.recv_free_video_v2(_receiveInstancePtr, ref videoFrame);
                        // Log.Warning("Skipping frame?",this);
                        _lastStatusMessage = "skipping frame";
                        break;
                    }

                    // get all our info so that we can free the frame
                    _xRes = videoFrame.xres;
                    _yRes = videoFrame.yres;
                    _stride = videoFrame.line_stride_in_bytes;

                    // Try to acquire our texture mutex for some time.
                    // End processing if we shall quit
                    while (!_textureMutex.WaitOne(10))
                    {
                        if (_exitThread)
                        {
                            // Always free received frame
                            NDIlib.recv_free_video_v2(_receiveInstancePtr, ref videoFrame);
                            Log.Warning("NDI input thread exiting.", this);
                            break;
                        }
                    }

                    // For now, we need to be on the UI thread to fill our bitmap
                    _textureAction = () =>
                                     {
                                         // If the local receiver Id is not the same as the global receiver Id,
                                         // then that means that either the connection source has changed, or
                                         // the window has closed, in which case the latest receiver Id
                                         // will be 0. If either is true, we stop processing data.
                                         if (currReceiverId != _receiverId || _receiverId == 0)
                                         {
                                             return;
                                         }

                                         if (_xRes == 0 || _yRes == 0 || _stride == 0)
                                         {
                                             // always free received frames
                                             NDIlib.recv_free_video_v2(_receiveInstancePtr, ref videoFrame);
                                             //Log.Warning("NDI input wxh = 0x0, skipping frame.", this);
                                             return;
                                         }

                                         // create several textures with a given format with CPU access
                                         // to be able to read out the initial texture values
                                         const Format textureFormat = Format.B8G8R8A8_UNorm;

                                         if (_imagesWithCpuAccess.Count == 0
                                             || _imagesWithCpuAccess[0].Description.Format != textureFormat
                                             || _imagesWithCpuAccess[0].Description.Width != _xRes
                                             || _imagesWithCpuAccess[0].Description.Height != _yRes
                                             || _imagesWithCpuAccess[0].Description.MipLevels != 1)
                                         {
                                             DebugDataRecording.KeepTraceData(this, "07-_textureActionCreateNewTexture", currReceiverId,
                                                                              ref _traceTextureAction2Channel);
                                             //Log.Warning("resolution or format changed", this);

                                             var imageDesc = new Texture2DDescription
                                                                 {
                                                                     BindFlags = BindFlags.ShaderResource,
                                                                     Format = textureFormat,
                                                                     Width = _xRes,
                                                                     Height = _yRes,
                                                                     MipLevels = 1,
                                                                     SampleDescription = new SampleDescription(1, 0),
                                                                     Usage = ResourceUsage.Dynamic,
                                                                     OptionFlags = ResourceOptionFlags.None,
                                                                     CpuAccessFlags = CpuAccessFlags.Write,
                                                                     ArraySize = 1
                                                                 };

                                             DisposeTextures();

                                             // Log.Debug($"NDI input wxh = {xRes}x{yRes}, " +
                                             //           $"format = {textureFormat} ({textureFormat})");

                                             for (var i = 0; i < NumTextureEntries; ++i)
                                             {
                                                 var tex2D = Texture2D.CreateTexture2D(imageDesc);
                                                 _imagesWithCpuAccess.Add(tex2D);
                                             }

                                             _currentIndex = 0;
                                         }

                                         // copy texture to an internal image
                                         var immediateContext = ResourceManager.Device.ImmediateContext;
                                         var writableImage = _imagesWithCpuAccess[_currentIndex];
                                         _currentIndex = (_currentIndex + 1) % NumTextureEntries;

                                         // NOTE: During profiling we can observe that this block is zero length if image index is 0 ???
                                         // We should investigate this, because there might be a bug in the code.
                                         if (_isProfiling)
                                             DebugDataRecording.StartRegion(this, "08-CopyTextureToIndex", _currentIndex, ref _traceTextureCopyChannel);

                                         // we have to map with a stride that represents multiples of 16 pixels here
                                         // (it is yet unclear why, but works)
                                         // map resource manually using our stride...
                                         var dataBox = immediateContext.MapSubresource(writableImage, 0, 0, MapMode.WriteDiscard,
                                                                                       SharpDX.Direct3D11.MapFlags.None, out int _);

                                         T3.Core.Utils.Utilities.CopyImageMemory(videoFrame.p_data, dataBox.DataPointer, _yRes,
                                                                                 videoFrame.line_stride_in_bytes, dataBox.RowPitch);

                                         // release our resources
                                         immediateContext.UnmapSubresource(writableImage, 0);
                                         _lastTexture = writableImage;

                                         if (_isProfiling)
                                             DebugDataRecording.EndRegion(_traceTextureCopyChannel);

                                         // free frames that were received after use
                                         NDIlib.recv_free_video_v2(_receiveInstancePtr, ref videoFrame);
                                         _lastStatusMessage = null;
                                     };

                    _textureMutex.ReleaseMutex();

                    break;

                // Ignore audio
                case NDIlib.frame_type_e.frame_type_audio:
                    break;

                // Metadata
                case NDIlib.frame_type_e.frame_type_metadata:

                    // UTF-8 strings must be converted for use - length includes the terminating zero
                    //String metadata = Utf8ToString(metadataFrame.p_data, metadataFrame.length-1);

                    //System.Diagnostics.Debug.Print(metadata);

                    // free frames that were received
                    NDIlib.recv_free_metadata(_receiveInstancePtr, ref metadataFrame);
                    break;
            }
        }
    }

    private void DisposeTextures()
    {
        Texture.Value = null;
        _lastTexture = null;

        foreach (var image in _imagesWithCpuAccess)
        {
            image.Dispose();
        }

        _imagesWithCpuAccess.Clear();
    }

    #region IDisposable Support



    protected override void Dispose(bool isDisposing)
    {

        if (!isDisposing)
            return;

        Log.Debug("Disposing NdiInput...", this);
        
        // This call happens when the window is closing, so we set the id
        // to 0 to signal we don't want to process any more frames.
        Interlocked.Exchange(ref _receiverId, 0);

        _exitThread = true;

        try
        {
            Task.Run(() => _ndiInputFinder.Dispose()).Wait(TimeSpan.FromSeconds(2));
        }
        catch (Exception ex)
        {
            Log.Warning("NDI Input Finder dispose timed out or failed: " + ex.Message);
        }
        
        // wait for it to exit
        if (_receiveThread != null)
        {
            _receiveThread.Join();
            _receiveThread = null;
        }

        // Destroy the receiver
        if (_receiveInstancePtr != IntPtr.Zero)
        {
            NDIlib.recv_destroy(_receiveInstancePtr);
            _receiveInstancePtr = IntPtr.Zero;
        }

        DisposeTextures();



        if (_initialized)
        {
            NDIlib.destroy();
            _initialized = false;
        }
    }
    
    #endregion

    private static bool _initialized;
    private readonly Finder _ndiInputFinder;

    // A pointer to our unmanaged NDI receiver instance
    private IntPtr _receiveInstancePtr = IntPtr.Zero;

    // Thread to receive frames on so that the UI is still functional
    private Thread? _receiveThread;

    // A way to exit the thread safely
    private bool _exitThread;

    /** should we send video to Windows or not? */
    private const bool VideoEnabled = true;

    /// <summary>
    /// This variable keeps track of the current Id of the receiver object. This
    /// is a way to avoid processing frames on the UI thread when either the
    /// connection source gets changed or the window closes.
    /// </summary>
    private int _receiverId;

    /** Hold several textures internally to speed up calculations */
    private const int NumTextureEntries = 3;

    private readonly List<Texture2D> _imagesWithCpuAccess = [];

    /** Current image index (used for circular access of ImagesWithCpuAccess) */
    private int _currentIndex;

    /** Mutex protecting changes to our images */
    private readonly Mutex _textureMutex = new();

    /** Action for changing the textures */
    private Action? _textureAction;

    private Texture2D? _lastTexture;

    #region status provider
    public IStatusProvider.StatusLevel GetStatusLevel()
    {
        return string.IsNullOrEmpty(_lastStatusMessage) ? IStatusProvider.StatusLevel.Success : IStatusProvider.StatusLevel.Warning;
    }

    public string? GetStatusMessage()
    {
        return _lastStatusMessage;
    }

    private string? _lastStatusMessage;
    #endregion

    #region device dropdown
    private const string PlaceholderText = "Select NDI source...";

    string ICustomDropdownHolder.GetValueForInput(Guid inputId)
    {
        var currentValue = SourceName.Value;

        // If no source is selected or it's the default "0", show placeholder
        if (string.IsNullOrEmpty(currentValue) || currentValue == "0")
            return PlaceholderText;

        // Check if the current value actually exists in available sources
        var sourceExists = _ndiInputFinder.Sources.Any(s => s.Name == currentValue);
        if (!sourceExists)
            return PlaceholderText;

        return currentValue;
    }

    IEnumerable<string> ICustomDropdownHolder.GetOptionsForInput(Guid inputId)
    {
        if (inputId != SourceName.Id)
        {
            yield return "undefined";
            yield break;
        }

        // Add the placeholder as the first option
        yield return PlaceholderText;

        // Add all available NDI sources
        foreach (var s in _ndiInputFinder.Sources)
        {
            yield return s.Name;
        }
    }

    void ICustomDropdownHolder.HandleResultForInput(Guid inputId, string? selected, bool isAListItem)
    {
        // If placeholder is selected, treat as no selection
        if (string.IsNullOrEmpty(selected) || selected == PlaceholderText)
        {
            SourceName.SetTypedInputValue(string.Empty);
            // Force a disconnect
            DisposeTextures();
            _lastStatusMessage = null;
            return;
        }

        SourceName.SetTypedInputValue(selected!);
    }
    #endregion

    private int _xRes;
    private int _yRes;
    private int _stride;
    
    private bool _isProfiling;
    private bool _reconnect;
    private DataChannel? _traceTallyChannel;
    private DataChannel? _traceReceiveThreadProc;
    private DataChannel? _traceReceive2ThreadProc;
    private DataChannel? _traceTextureCopyChannel;
    private DataChannel? _traceTextureAction2Channel;

    [Input(Guid = "FD1FCA6B-A3BE-440B-86BA-6B7B1BBD2A8C")]
    public readonly InputSlot<string> SourceName = new();

    [Input(Guid = "3F634E98-93F2-4B5E-A098-623B3F8E4C9C")]
    public readonly InputSlot<bool> EnableProfiling = new();

    [Input(Guid = "5E1EC76B-8FFE-43CA-867B-C9DDA0EAFB60")]
    public readonly InputSlot<bool> TriggerReconnect = new();
}