using Godot;
using System;
using System.Runtime.InteropServices;
using System.Threading.Tasks;

namespace VideoOrchestra.Platform
{
    /// <summary>
    /// Windows VP9 decoder implementation using Media Foundation
    /// </summary>
    public class WindowsVP9Decoder : IVP9PlatformDecoder
    {
        private const int MAX_STREAMS = 3;
        private const uint MFSTARTUP_NOSOCKET = 0x1;
        private const uint MFSTARTUP_LITE = 0x1;
        private const uint MFSTARTUP_FULL = 0x0;
        
        // Media Foundation interfaces and structures
        private IntPtr[] _mediaFoundationDecoders = new IntPtr[MAX_STREAMS];
        private IntPtr[] _d3d11Textures = new IntPtr[MAX_STREAMS];
        private ImageTexture[] _godotTextures = new ImageTexture[MAX_STREAMS];
        private bool _initialized = false;
        private bool _hardwareEnabled = true;
        private int _width = 0;
        private int _height = 0;
        private VP9DecoderStatus _status = VP9DecoderStatus.Uninitialized;
        
        public string PlatformName => "Windows";
        public bool IsHardwareDecodingSupported => CheckHardwareSupport();
        
        #region Media Foundation P/Invoke Declarations
        
        [DllImport("mfplat.dll", CallingConvention = CallingConvention.StdCall)]
        private static extern int MFStartup(uint version, uint flags);
        
        [DllImport("mfplat.dll", CallingConvention = CallingConvention.StdCall)]
        private static extern int MFShutdown();
        
        [DllImport("mfplat.dll", CallingConvention = CallingConvention.StdCall)]
        private static extern int MFCreateMediaType(out IntPtr mediaType);
        
        [DllImport("mf.dll", CallingConvention = CallingConvention.StdCall)]
        private static extern int MFCreateSourceResolver(out IntPtr sourceResolver);
        
        [DllImport("mf.dll", CallingConvention = CallingConvention.StdCall)]
        private static extern int MFCreateTopology(out IntPtr topology);
        
        [DllImport("d3d11.dll", CallingConvention = CallingConvention.StdCall)]
        private static extern int D3D11CreateDevice(
            IntPtr adapter, uint driverType, IntPtr software, uint flags,
            IntPtr featureLevels, uint featureLevelCount, uint sdkVersion,
            out IntPtr device, out uint featureLevel, out IntPtr context);
        
        // GUIDs for Media Foundation
        private static readonly Guid MF_MT_MAJOR_TYPE = new("48eba18e-f8c9-4687-bf11-0a74c9f96a8f");
        private static readonly Guid MF_MT_SUBTYPE = new("f7e34c9a-42e8-4714-b74b-cb29d72c35e5");
        private static readonly Guid MFMediaType_Video = new("73646976-0000-0010-8000-00aa00389b71");
        private static readonly Guid MFVideoFormat_VP90 = new("30395056-0000-0010-8000-00aa00389b71");
        private static readonly Guid MFVideoFormat_NV12 = new("3231564e-0000-0010-8000-00aa00389b71");
        
        #endregion
        
        public WindowsVP9Decoder()
        {
            for (int i = 0; i < MAX_STREAMS; i++)
            {
                _mediaFoundationDecoders[i] = IntPtr.Zero;
                _d3d11Textures[i] = IntPtr.Zero;
                _godotTextures[i] = null;
            }
        }
        
        public bool Initialize(int width, int height, bool enableHardware = true)
        {
            try
            {
                _width = width;
                _height = height;
                _hardwareEnabled = enableHardware && IsHardwareDecodingSupported;
                bool mediaFoundationAvailable = false;
                
                // Initialize Media Foundation
                try
                {
                    // Use version 2.0 (0x00020070) and LITE startup mode for basic functionality
                    int hr = MFStartup(0x00020070, MFSTARTUP_LITE);
                    if (hr != 0)
                    {
                        // Try full mode as fallback
                        hr = MFStartup(0x00020070, MFSTARTUP_FULL);
                        if (hr != 0)
                        {
                            // Common error codes:
                            // 0xC00D36E3 = MF_E_PLATFORM_NOT_INITIALIZED
                            // 0xC00D36E4 = MF_E_ALREADY_INITIALIZED
                            string errorMsg = hr switch
                            {
                                unchecked((int)0xC00D36E3) => "Media Foundation platform not available",
                                unchecked((int)0xC00D36E4) => "Media Foundation already initialized (continuing)",
                                unchecked((int)0x80004005) => "Media Foundation access denied",
                                _ => $"Media Foundation startup failed with HRESULT 0x{hr:X8}"
                            };
                            
                            if (hr == unchecked((int)0xC00D36E4))
                            {
                                // Already initialized is OK, we can continue
                                GD.Print("Media Foundation already initialized, continuing...");
                                mediaFoundationAvailable = true;
                            }
                            else
                            {
                                GD.PrintErr($"Windows Media Foundation initialization failed: {errorMsg}");
                                GD.Print("Falling back to software-only simulation mode...");
                                mediaFoundationAvailable = false;
                                _hardwareEnabled = false;
                            }
                        }
                        else
                        {
                            mediaFoundationAvailable = true;
                        }
                    }
                    else
                    {
                        mediaFoundationAvailable = true;
                    }
                }
                catch (DllNotFoundException)
                {
                    GD.Print("Media Foundation DLLs not found, using software simulation mode");
                    mediaFoundationAvailable = false;
                    _hardwareEnabled = false;
                }
                catch (Exception ex)
                {
                    GD.PrintErr($"Media Foundation initialization exception: {ex.Message}");
                    mediaFoundationAvailable = false;
                    _hardwareEnabled = false;
                }
                
                // Initialize D3D11 device for hardware decoding if enabled
                if (_hardwareEnabled && mediaFoundationAvailable)
                {
                    if (!InitializeD3D11())
                    {
                        GD.Print("Warning: Failed to initialize D3D11, falling back to software decoding");
                        _hardwareEnabled = false;
                    }
                }
                
                // Initialize decoders for each stream
                for (int i = 0; i < MAX_STREAMS; i++)
                {
                    if (!InitializeStreamDecoder(i))
                    {
                        GD.PrintErr($"Failed to initialize decoder for stream {i}");
                        
                        // Don't fail completely - continue with simulation mode
                        GD.Print($"Using simulation mode for stream {i}");
                        _mediaFoundationDecoders[i] = new IntPtr(i + 100); // Simulation placeholder
                    }
                    
                    _godotTextures[i] = new ImageTexture();
                }
                
                _initialized = true;
                _status = VP9DecoderStatus.Initialized;
                
                string mode = mediaFoundationAvailable ? 
                    (_hardwareEnabled ? "Hardware (Media Foundation)" : "Software (Media Foundation)") : 
                    "Simulation";
                    
                GD.Print($"Windows VP9 decoder initialized: {width}x{height}, Mode: {mode}");
                return true;
            }
            catch (Exception ex)
            {
                GD.PrintErr($"Error initializing Windows VP9 decoder: {ex.Message}");
                _status = VP9DecoderStatus.Error;
                Release();
                return false;
            }
        }
        
        private bool CheckHardwareSupport()
        {
            try
            {
                // Check for D3D11 and VP9 hardware decoder support
                IntPtr device, context;
                uint featureLevel;
                
                int hr = D3D11CreateDevice(
                    IntPtr.Zero, 1, IntPtr.Zero, 0,
                    IntPtr.Zero, 0, 7, out device, out featureLevel, out context);
                
                if (hr == 0 && device != IntPtr.Zero)
                {
                    Marshal.Release(device);
                    Marshal.Release(context);
                    return true;
                }
                
                return false;
            }
            catch
            {
                return false;
            }
        }
        
        private bool InitializeD3D11()
        {
            try
            {
                // Initialize D3D11 device for hardware-accelerated decoding
                // This would create the D3D11 device and context needed for Media Foundation
                // For now, we'll simulate this initialization
                return true;
            }
            catch (Exception ex)
            {
                GD.PrintErr($"Failed to initialize D3D11: {ex.Message}");
                return false;
            }
        }
        
        private bool InitializeStreamDecoder(int streamId)
        {
            try
            {
                // Create Media Foundation decoder for this stream
                // This would involve:
                // 1. Creating IMFTransform for VP9 decoder
                // 2. Setting input/output media types
                // 3. Configuring for hardware acceleration if enabled
                
                // For now, we'll simulate successful initialization
                _mediaFoundationDecoders[streamId] = new IntPtr(streamId + 1); // Non-null placeholder
                return true;
            }
            catch (Exception ex)
            {
                GD.PrintErr($"Failed to initialize decoder for stream {streamId}: {ex.Message}");
                return false;
            }
        }
        
        public bool DecodeFrame(byte[] frameData, int streamId)
        {
            if (!_initialized || streamId < 0 || streamId >= MAX_STREAMS)
            {
                return false;
            }
            
            if (frameData == null || frameData.Length == 0)
            {
                return false;
            }
            
            try
            {
                _status = VP9DecoderStatus.Decoding;
                
                // Process VP9 frame through Media Foundation
                bool success = ProcessFrameWithMediaFoundation(frameData, streamId);
                
                if (success)
                {
                    // Update Godot texture with decoded frame
                    UpdateGodotTexture(streamId);
                }
                else
                {
                    _status = VP9DecoderStatus.Error;
                }
                
                return success;
            }
            catch (Exception ex)
            {
                GD.PrintErr($"Error decoding frame for stream {streamId}: {ex.Message}");
                _status = VP9DecoderStatus.Error;
                return false;
            }
        }
        
        private bool ProcessFrameWithMediaFoundation(byte[] frameData, int streamId)
        {
            try
            {
                // This would involve:
                // 1. Creating IMFSample from input data
                // 2. Calling IMFTransform.ProcessInput()
                // 3. Calling IMFTransform.ProcessOutput() to get decoded frame
                // 4. Converting output to texture format
                
                // For demonstration, simulate successful decode
                GD.Print($"[Windows MF] Decoding frame for stream {streamId}: {frameData.Length} bytes");
                
                // Simulate some processing time
                Task.Delay(1).Wait();
                
                return true;
            }
            catch (Exception ex)
            {
                throw new VP9DecoderException(PlatformName, streamId, $"Media Foundation decode failed: {ex.Message}");
            }
        }
        
        private void UpdateGodotTexture(int streamId)
        {
            try
            {
                // Create dummy texture data for demonstration
                // In real implementation, this would convert the decoded frame from Media Foundation
                // to a format Godot can use (RGBA8 or similar)
                
                var image = Image.CreateEmpty(_width, _height, false, Image.Format.Rgba8);
                
                // Fill with a pattern to show it's working (different color per stream)
                var color = streamId switch
                {
                    0 => Colors.Red,
                    1 => Colors.Green,
                    2 => Colors.Blue,
                    _ => Colors.White
                };
                
                image.Fill(color);
                _godotTextures[streamId].SetImage(image);
                
                GD.Print($"Updated texture for stream {streamId}");
            }
            catch (Exception ex)
            {
                GD.PrintErr($"Failed to update texture for stream {streamId}: {ex.Message}");
            }
        }
        
        public ImageTexture GetDecodedTexture(int streamId)
        {
            if (!_initialized || streamId < 0 || streamId >= MAX_STREAMS)
            {
                return null;
            }
            
            return _godotTextures[streamId];
        }
        
        public uint GetNativeTextureId(int streamId)
        {
            if (!_initialized || streamId < 0 || streamId >= MAX_STREAMS)
            {
                return 0;
            }
            
            // Return D3D11 texture handle if available
            return (uint)_d3d11Textures[streamId].ToInt64();
        }
        
        public VP9DecoderStatus GetStatus()
        {
            return _status;
        }
        
        public void Release()
        {
            try
            {
                _status = VP9DecoderStatus.Released;
                
                // Release Media Foundation resources
                for (int i = 0; i < MAX_STREAMS; i++)
                {
                    if (_mediaFoundationDecoders[i] != IntPtr.Zero)
                    {
                        // Release IMFTransform
                        Marshal.Release(_mediaFoundationDecoders[i]);
                        _mediaFoundationDecoders[i] = IntPtr.Zero;
                    }
                    
                    if (_d3d11Textures[i] != IntPtr.Zero)
                    {
                        // Release D3D11 texture
                        Marshal.Release(_d3d11Textures[i]);
                        _d3d11Textures[i] = IntPtr.Zero;
                    }
                    
                    _godotTextures[i]?.Dispose();
                    _godotTextures[i] = null;
                }
                
                // Shutdown Media Foundation if it was initialized
                if (_initialized)
                {
                    try
                    {
                        MFShutdown();
                    }
                    catch (Exception ex)
                    {
                        GD.Print($"Warning: Error shutting down Media Foundation: {ex.Message}");
                    }
                }
                
                _initialized = false;
                GD.Print("Windows VP9 decoder released");
            }
            catch (Exception ex)
            {
                GD.PrintErr($"Error releasing Windows VP9 decoder: {ex.Message}");
            }
        }
        
        public void Dispose()
        {
            Release();
        }
    }
}