using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Text;
using OpenToolkit.Graphics.OpenGL4;
using Robust.Shared;
using Robust.Shared.Log;
using Robust.Shared.Map;
using Robust.Shared.Maths;
using Robust.Shared.Utility;
using TerraFX.Interop.DirectX;
using TerraFX.Interop.Windows;
using static Robust.Client.Graphics.Clyde.Egl;
using static TerraFX.Interop.DirectX.D3D_DRIVER_TYPE;
using static TerraFX.Interop.DirectX.D3D_FEATURE_LEVEL;
using static TerraFX.Interop.DirectX.DXGI_FORMAT;
using static TerraFX.Interop.DirectX.DXGI_SWAP_EFFECT;
using static TerraFX.Interop.Windows.Windows;
using static TerraFX.Interop.DirectX.DirectX;
using static TerraFX.Interop.DirectX.D3D11;
using static TerraFX.Interop.DirectX.DXGI;
using GL = OpenToolkit.Graphics.OpenGL4.GL;


namespace Robust.Client.Graphics.Clyde
{
    internal partial class Clyde
    {
        /// <summary>
        ///     Explicit ANGLE GL context with manual DXGI/D3D device and swap chain management.
        /// </summary>
        private sealed unsafe class GLContextAngle : GLContextBase
        {
            // Thanks to mpv's implementation of context_angle for inspiration/hints.
            // https://github.com/mpv-player/mpv/blob/f8e62d3d82dd0a3d06f9a557d756f0ad78118cc7/video/out/opengl/context_angle.c

            // NOTE: This class only handles GLES3/D3D11.
            // For anything lower we just let ANGLE fall back and do the work 100%.

            private IDXGIFactory1* _factory;
            private IDXGIAdapter1* _adapter;
            private ID3D11Device* _device;
            private D3D_FEATURE_LEVEL _deviceFl;
            private void* _eglDevice;
            private void* _eglDisplay;
            private void* _eglContext;
            private void* _eglConfig;

            private bool _es3;
            private uint _swapInterval;

            private readonly Dictionary<WindowId, WindowData> _windowData = new();

            public override GLContextSpec[] SpecsToTry => Array.Empty<GLContextSpec>();
            public override bool RequireWindowGL => false;
            public override bool EarlyContextInit => true;
            public override bool HasBrokenWindowSrgb => false;

            public GLContextAngle(Clyde clyde) : base(clyde)
            {
            }

            public override GLContextSpec? SpecWithOpenGLVersion(RendererOpenGLVersion version)
            {
                // Do not initialize GL context on the window directly, we use ANGLE.
                return null;
            }

            public override void UpdateVSync()
            {
                _swapInterval = (uint) (Clyde._vSync ? 1 : 0);
            }

            public override void WindowCreated(GLContextSpec? spec, WindowReg reg)
            {
                var data = new WindowData
                {
                    Reg = reg
                };
                _windowData[reg.Id] = data;

                var hWnd = (HWND) Clyde._windowing!.WindowGetWin32Window(reg)!.Value;

                // todo: exception management.
                CreateSwapChain1(hWnd, data);

                _factory->MakeWindowAssociation(hWnd, DXGI_MWA_NO_ALT_ENTER);

                var rt = Clyde.RtToLoaded(reg.RenderTarget);
                rt.FlipY = true;

                if (reg.IsMainWindow)
                {
                    UpdateVSync();
                    eglMakeCurrent(_eglDisplay, data.EglBackbuffer, data.EglBackbuffer, _eglContext);
                }
            }

            private void DestroyBackbuffer(WindowData data)
            {
                if (data.EglBackbuffer != null)
                {
                    if (data.Reg.IsMainWindow)
                        eglMakeCurrent(_eglDisplay, null, null, null);
                    eglDestroySurface(_eglDisplay, data.EglBackbuffer);

                    data.EglBackbuffer = null;
                }

                data.Backbuffer->Release();
                data.Backbuffer = null;
            }

            private void SetupBackbuffer(WindowData data)
            {
                DebugTools.Assert(data.Backbuffer == null, "Backbuffer must have been released!");
                DebugTools.Assert(data.EglBackbuffer == null, "EGL Backbuffer must have been released!");

                fixed (ID3D11Texture2D** texPtr = &data.Backbuffer)
                {
                    ThrowIfFailed("GetBuffer", data.SwapChain->GetBuffer(0, __uuidof<ID3D11Texture2D>(), (void**) texPtr));
                }

                var attributes = stackalloc int[]
                {
                    EGL_TEXTURE_FORMAT, EGL_TEXTURE_RGBA,
                    EGL_TEXTURE_TARGET, EGL_TEXTURE_2D,
                    EGL_NONE
                };

                data.EglBackbuffer = eglCreatePbufferFromClientBuffer(
                    _eglDisplay,
                    EGL_D3D_TEXTURE_ANGLE,
                    data.Backbuffer,
                    _eglConfig,
                    attributes);
            }

            private void CreateSwapChain1(HWND hWnd, WindowData data)
            {
                var desc = new DXGI_SWAP_CHAIN_DESC
                {
                    BufferDesc =
                    {
                        Width = (uint) data.Reg.FramebufferSize.X,
                        Height = (uint) data.Reg.FramebufferSize.Y,
                        Format =  Clyde._hasGLSrgb ? DXGI_FORMAT_R8G8B8A8_UNORM_SRGB : DXGI_FORMAT_R8G8B8A8_UNORM
                    },
                    SampleDesc =
                    {
                        Count = 1
                    },
                    OutputWindow = hWnd,
                    BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT | DXGI_USAGE_SHADER_INPUT,
                    BufferCount = 2,
                    SwapEffect = DXGI_SWAP_EFFECT_DISCARD,
                    Windowed = 1
                };

                fixed (IDXGISwapChain** swapPtr = &data.SwapChain)
                {
                    ThrowIfFailed("CreateSwapChain", _factory->CreateSwapChain(
                        (IUnknown*) _device,
                        &desc,
                        swapPtr
                    ));
                }

                SetupBackbuffer(data);
            }

            public override void WindowDestroyed(WindowReg reg)
            {
                var data = _windowData[reg.Id];

                DestroyBackbuffer(data);
                data.SwapChain->Release();

                _windowData.Remove(reg.Id);
            }

            public bool TryInitialize()
            {
                try
                {
                    TryInitializeCore();
                }
                catch (Exception e)
                {
                    Logger.ErrorS("clyde.ogl.angle", $"Failed to initialize custom ANGLE: {e}");
                    Shutdown();
                    return false;
                }

                return true;
            }

            public void EarlyInit()
            {
                // Early GL context init so that feature detection runs before window creation,
                // and so that we can know _hasGLSrgb in window creation.
                eglMakeCurrent(_eglDisplay, null, null, _eglContext);
                Clyde.InitOpenGL();
                Clyde._earlyGLInit = true;
            }

            private void TryInitializeCore()
            {
                var extensions = Marshal.PtrToStringUTF8((nint) eglQueryString(null, EGL_EXTENSIONS));
                Logger.DebugS("clyde.ogl.angle", $"EGL client extensions: {extensions}!");

                CreateD3D11Device();
                CreateEglContext();
            }

            private void CreateEglContext()
            {
                _eglDevice = eglCreateDeviceANGLE(EGL_D3D11_DEVICE_ANGLE, _device, null);
                if (_eglDevice == (void*) EGL_NO_DEVICE_EXT)
                    throw new Exception("eglCreateDeviceANGLE failed.");

                _eglDisplay = eglGetPlatformDisplayEXT(EGL_PLATFORM_DEVICE_EXT, _eglDevice, null);
                if (_eglDisplay == null)
                    throw new Exception("eglGetPlatformDisplayEXT failed.");

                int major;
                int minor;
                if (eglInitialize(_eglDisplay, &major, &minor) == EGL_FALSE)
                    throw new Exception("eglInitialize failed.");

                var vendor = Marshal.PtrToStringUTF8((nint) eglQueryString(_eglDisplay, EGL_VENDOR));
                var version = Marshal.PtrToStringUTF8((nint) eglQueryString(_eglDisplay, EGL_VERSION));
                var extensions = Marshal.PtrToStringUTF8((nint) eglQueryString(_eglDisplay, EGL_EXTENSIONS));

                Logger.DebugS("clyde.ogl.angle", "EGL initialized!");
                Logger.DebugS("clyde.ogl.angle", $"EGL vendor: {vendor}!");
                Logger.DebugS("clyde.ogl.angle", $"EGL version: {version}!");
                Logger.DebugS("clyde.ogl.angle", $"EGL extensions: {extensions}!");

                if (eglBindAPI(EGL_OPENGL_ES_API) != EGL_TRUE)
                    throw new Exception("eglBindAPI failed.");

                var attribs = stackalloc int[]
                {
                    // EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
                    EGL_RED_SIZE, 8,
                    EGL_GREEN_SIZE, 8,
                    EGL_BLUE_SIZE, 8,
                    EGL_ALPHA_SIZE, 8,
                    EGL_STENCIL_SIZE, 8,
                    EGL_NONE
                };

                var numConfigs = 0;
                if (eglChooseConfig(_eglDisplay, attribs, null, 0, &numConfigs) == EGL_FALSE)
                    throw new Exception("eglChooseConfig failed.");

                var configs = stackalloc void*[numConfigs];
                if (eglChooseConfig(_eglDisplay, attribs, configs, numConfigs, &numConfigs) == EGL_FALSE)
                    throw new Exception("eglChooseConfig failed.");

                if (numConfigs == 0)
                    throw new Exception("No compatible EGL configurations returned!");

                Logger.DebugS("clyde.ogl.angle", $"{numConfigs} EGL configs possible!");

                for (var i = 0; i < numConfigs; i++)
                {
                    Logger.DebugS("clyde.ogl.angle", DumpEglConfig(_eglDisplay, configs[i]));
                }

                _eglConfig = configs[0];

                int supportedRenderableTypes;
                eglGetConfigAttrib(_eglDisplay, _eglConfig, EGL_RENDERABLE_TYPE, &supportedRenderableTypes);

                _es3 = (supportedRenderableTypes & EGL_OPENGL_ES3_BIT) != 0;

                var createAttribs = stackalloc int[]
                {
                    EGL_CONTEXT_CLIENT_VERSION, _es3 ? 3 : 2,
                    EGL_NONE
                };

                _eglContext = eglCreateContext(_eglDisplay, _eglConfig, null, createAttribs);
                if (_eglContext == (void*) EGL_NO_CONTEXT)
                    throw new Exception("eglCreateContext failed!");

                Logger.DebugS("clyde.ogl.angle", "EGL context created!");

                Clyde._openGLVersion = _es3 ? RendererOpenGLVersion.GLES3 : RendererOpenGLVersion.GLES2;
            }

            private void CreateD3D11Device()
            {
                IDXGIDevice1* dxgiDevice = null;

                try
                {
                    fixed (IDXGIFactory1** ptr = &_factory)
                    {
                        ThrowIfFailed(nameof(CreateDXGIFactory1), CreateDXGIFactory1(__uuidof<IDXGIFactory1>(), (void**) ptr));
                    }

                    // Try to find the correct adapter if specified.
                    var adapterName = Clyde._cfg.GetCVar(CVars.DisplayAdapter);

                    if (adapterName != "")
                    {
                        _adapter = TryFindAdapterWithName(adapterName);

                        if (_adapter == null)
                        {
                            Logger.WarningS("clyde.ogl.angle",
                                $"Unable to find display adapter with requested name: {adapterName}");
                        }

                        Logger.DebugS("clyde.ogl.angle", $"Found display adapter with name: {adapterName}");
                    }

#pragma warning disable CA1416
#pragma warning disable CS0162
                    IDXGIFactory6* factory6;
                    if (_adapter == null && _factory->QueryInterface(__uuidof<IDXGIFactory6>(), (void**) &factory6) == 0)
                    {
                        var gpuPref = (DXGI_GPU_PREFERENCE) Clyde._cfg.GetCVar(CVars.DisplayGpuPreference);
                        IDXGIAdapter1* adapter;
                        for (var adapterIndex = 0u;
                             factory6->EnumAdapterByGpuPreference(
                                 adapterIndex,
                                 gpuPref,
                                 __uuidof<IDXGIAdapter1>(),
                                 (void**)&adapter) != DXGI_ERROR_NOT_FOUND;
                             adapterIndex++)
                        {
                            /*
                            DXGI_ADAPTER_DESC1 aDesc;
                            ThrowIfFailed("GetDesc1", adapter->GetDesc1(&aDesc));

                            var aDescName = new ReadOnlySpan<char>(aDesc.Description, 128);

                            Logger.DebugS("clyde.ogl.angle", aDescName.ToString());

                            adapter->Release();
                            */
                            _adapter = adapter;
                            break;
                        }

                        factory6->Release();
                    }
#pragma warning restore CS0162
#pragma warning restore CA1416

                    Span<D3D_FEATURE_LEVEL> featureLevels = stackalloc D3D_FEATURE_LEVEL[]
                    {
                        // 11_0 can do GLES3
                        D3D_FEATURE_LEVEL_11_0,
                        // 9_3 can do GLES2
                        D3D_FEATURE_LEVEL_9_3,
                        // If we get a 9_1 FL we can't do D3D11 based ANGLE,
                        // but ANGLE can do it manually via the D3D9 renderer.
                        // In this case, abort custom swap chain and let ANGLE handle everything.
                        D3D_FEATURE_LEVEL_9_1
                    };

                    if (Clyde._cfg.GetCVar(CVars.DisplayAngleForceEs2))
                    {
                        featureLevels = stackalloc D3D_FEATURE_LEVEL[]
                        {
                            // Don't allow FL 11_0 so ANGLE is forced to init GLES2.
                            D3D_FEATURE_LEVEL_9_3,
                            D3D_FEATURE_LEVEL_9_1
                        };
                    }

                    if (Clyde._cfg.GetCVar(CVars.DisplayAngleForce10_0))
                    {
                        featureLevels = stackalloc D3D_FEATURE_LEVEL[]
                        {
                            D3D_FEATURE_LEVEL_10_0,
                        };
                    }

                    fixed (ID3D11Device** device = &_device)
                    fixed (D3D_FEATURE_LEVEL* fl = &featureLevels[0])
                    {
                        ThrowIfFailed("D3D11CreateDevice", D3D11CreateDevice(
                            (IDXGIAdapter*) _adapter,
                            _adapter == null ? D3D_DRIVER_TYPE_HARDWARE : D3D_DRIVER_TYPE_UNKNOWN,
                            HMODULE.NULL,
                            0,
                            fl,
                            (uint) featureLevels.Length,
                            D3D11_SDK_VERSION,
                            device,
                            null,
                            null
                        ));
                    }

                    // Get adapter from the device.

                    ThrowIfFailed("QueryInterface", _device->QueryInterface(__uuidof<IDXGIDevice1>(), (void**) &dxgiDevice));

                    fixed (IDXGIAdapter1** ptrAdapter = &_adapter)
                    {
                        ThrowIfFailed("GetParent", dxgiDevice->GetParent(__uuidof<IDXGIAdapter1>(), (void**) ptrAdapter));
                    }

                    _deviceFl = _device->GetFeatureLevel();

                    DXGI_ADAPTER_DESC1 desc;
                    ThrowIfFailed("GetDesc1", _adapter->GetDesc1(&desc));

                    var descName = ((ReadOnlySpan<char>)desc.Description).TrimEnd('\0');

                    Logger.DebugS("clyde.ogl.angle", "Successfully created D3D11 device!");
                    Logger.DebugS("clyde.ogl.angle", $"D3D11 Device Adapter: {descName.ToString()}");
                    Logger.DebugS("clyde.ogl.angle", $"D3D11 Device FL: {_deviceFl}");

                    if (_deviceFl == D3D_FEATURE_LEVEL_9_1)
                    {
                        throw new Exception(
                            "D3D11 device has too low FL (need at least 9_3). Aborting custom swap chain!");
                    }
                }
                finally
                {
                    if (dxgiDevice != null)
                        dxgiDevice->Release();
                }
            }

            public override void Shutdown()
            {
                // Shut down ANGLE.
                if (_eglDisplay != null)
                    eglTerminate(_eglDisplay);

                if (_eglDevice != null)
                    eglReleaseDeviceANGLE(_eglDevice);

                // Shut down D3D11/DXGI
                if (_factory != null)
                    _factory->Release();

                if (_adapter != null)
                    _adapter->Release();

                if (_device != null)
                    _device->Release();
            }

            public override void SwapAllBuffers()
            {
                foreach (var data in _windowData.Values)
                {
                    data.SwapChain->Present(_swapInterval, 0);
                }
            }

            public override void WindowResized(WindowReg reg, Vector2i oldSize)
            {
                var data = _windowData[reg.Id];
                DestroyBackbuffer(data);

                ThrowIfFailed("ResizeBuffers", data.SwapChain->ResizeBuffers(
                    2,
                    (uint) reg.FramebufferSize.X, (uint) reg.FramebufferSize.Y,
                    Clyde._hasGLSrgb ? DXGI_FORMAT_R8G8B8A8_UNORM_SRGB : DXGI_FORMAT_R8G8B8A8_UNORM,
                    0));

                SetupBackbuffer(data);

                if (reg.IsMainWindow)
                    eglMakeCurrent(_eglDisplay, data.EglBackbuffer, data.EglBackbuffer, _eglContext);
            }

            private IDXGIAdapter1* TryFindAdapterWithName(string name)
            {
                uint idx = 0;

                while (true)
                {
                    IDXGIAdapter1* adapter;
                    var hr = _factory->EnumAdapters1(idx++, &adapter);
                    if (hr == DXGI_ERROR_NOT_FOUND)
                        break;

                    ThrowIfFailed("EnumAdapters1", hr);

                    DXGI_ADAPTER_DESC1 desc;
                    ThrowIfFailed("GetDesc1", adapter->GetDesc1(&desc));

                    var descName = ((ReadOnlySpan<char>)desc.Description);

                    if (descName.StartsWith(name))
                        return adapter;

                    adapter->Release();
                }

                return null;
            }

            public override void* GetProcAddress(string name)
            {
                Span<byte> buf = stackalloc byte[128];
                var len = Encoding.UTF8.GetBytes(name, buf);
                buf[len] = 0;

                fixed (byte* ptr = &buf[0])
                {
                    return eglGetProcAddress(ptr);
                }
            }

            public override void BindWindowRenderTarget(WindowId rtWindowId)
            {
                var data = _windowData[rtWindowId];
                var result = eglMakeCurrent(_eglDisplay, data.EglBackbuffer, data.EglBackbuffer, _eglContext);
                if (result == EGL_FALSE)
                    throw new Exception("eglMakeCurrent failed.");

                GL.BindFramebuffer(FramebufferTarget.Framebuffer, 0);
                Clyde.CheckGlError();
            }

            private static void ThrowIfFailed(string methodName, HRESULT hr)
            {
                if (FAILED(hr))
                {
                    Marshal.ThrowExceptionForHR(hr);
                }
            }

            private static string DumpEglConfig(void* display, void* config)
            {
                var sb = new StringBuilder();

                sb.Append($"cfg: {Get(EGL_CONFIG_ID):000} | ");
                sb.AppendFormat(
                    "R/G/B/A/D/S: {0}/{1}/{2}/{3}/{4:00}/{5} | ",
                    Get(EGL_RED_SIZE), Get(EGL_GREEN_SIZE), Get(EGL_BLUE_SIZE), Get(EGL_ALPHA_SIZE),
                    Get(EGL_DEPTH_SIZE), Get(EGL_STENCIL_SIZE));

                // COLOR_BUFFER_TYPE
                sb.Append($"CBT: {Get(EGL_COLOR_BUFFER_TYPE)} | ");
                sb.Append($"CC: {Get(EGL_CONFIG_CAVEAT)} | ");
                sb.Append($"CONF: {Get(EGL_CONFORMANT)} | ");
                sb.Append($"NAT: {Get(EGL_NATIVE_VISUAL_ID)} | ");
                sb.Append($"SAMPLES: {Get(EGL_SAMPLES)} | ");
                sb.Append($"SAMPLE_BUFFERS: {Get(EGL_SAMPLE_BUFFERS)} | ");
                sb.Append($"ORIENTATION: {Get(EGL_OPTIMAL_SURFACE_ORIENTATION_ANGLE)} | ");
                sb.Append($"RENDERABLE: {Get(EGL_RENDERABLE_TYPE)}");

                return sb.ToString();

                int Get(int attrib)
                {
                    int value;
                    if (eglGetConfigAttrib(display, config, attrib, &value) == EGL_FALSE)
                        throw new Exception("eglGetConfigAttrib failed!");

                    return value;
                }
            }

            private sealed class WindowData
            {
                public WindowReg Reg = default!;

                public IDXGISwapChain* SwapChain;
                public ID3D11Texture2D* Backbuffer;
                public void* EglBackbuffer;
            }
        }
    }
}