using StgSharp.Logic;
using StgSharp.Math;

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace StgSharp.Graphics
{
    internal unsafe partial class GLonUpdate : IglFunc
    {
        private static FrameOperationBuffer frameOpBuffer;
        private GLcontext* api;
        private IntPtr SwapBufferPtr = (IntPtr)(delegate*<IntPtr, void>)&InternalIO.glfwSwapBuffers;
        private glSHandle unupdatedFrame = glSHandle.Alloc(0);

        internal GLonUpdate(GLcontext* context)
        {
            if (frameOpBuffer == null)
            {
                frameOpBuffer = new FrameOperationBuffer();
            }
            api = context;
        }

        GLcontext* IglFunc.Context
        {
            get => api;
        }

        public FrameOperationBuffer ActivatedOperationBuffer
        {
            get { return frameOpBuffer; }
            set { frameOpBuffer = value; }
        }

        void IglFunc.ActiveTexture(uint type)
        {
            frameOpBuffer.Enqueue(type);
            frameOpBuffer.Enqueue(ActiveTexturePtr);
        }

        void IglFunc.AfterAlign(Form form, Action action)
        {
            throw new NotImplementedException();
        }

        void IglFunc.AlignFrame(Form form)
        {
            throw new NotImplementedException();
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe void IglFunc.AttachShader(glHandle program, glHandle shader)
        {
            frameOpBuffer.Enqueue(program, shader);
            frameOpBuffer.Enqueue(AttachShaderPtr);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.BindBuffer(BufferType bufferType, glHandle handle)
        {
            M128 m = default;
            m.Write<uint>(0, (uint)bufferType);
            m.Write<ulong>(1, (ulong)handle.valuePtr);
            frameOpBuffer.Enqueue(m);
            frameOpBuffer.Enqueue(BindBufferPtr);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.BindTexture(uint type, glHandle texture)
        {
            M128 m = default;
            m.Write<uint>(0, (uint)type);
            m.Write<ulong>(1, (ulong)texture.valuePtr);
            frameOpBuffer.Enqueue(m);
            frameOpBuffer.Enqueue(BindTexturePtr);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.BindVertexArray(glHandle index)
        {
            frameOpBuffer.Enqueue(index);
            frameOpBuffer.Enqueue(BindVertexArrayPtr);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.Clear(MaskBufferBit mask)
        {
            frameOpBuffer.Enqueue((int)mask);
            frameOpBuffer.Enqueue(ClearPtr);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.ClearColor(float R, float G, float B, float A)
        {
            frameOpBuffer.Enqueue(R, G, B, A);
            frameOpBuffer.Enqueue(ClearColorPtr);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.ClearGraphicError()
        {
            frameOpBuffer.Enqueue(ClearGraphicErrorPtr);
        }

        unsafe void IglFunc.CompileShader(glHandle shaderhandle)
        {
            frameOpBuffer.Enqueue((IntPtr)shaderhandle.valuePtr);
            frameOpBuffer.Enqueue(CompileShaderPtr);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        glHandle IglFunc.CreateProgram()
        {
            glHandle h = glHandle.Alloc(1);
            frameOpBuffer.Enqueue(h);
            frameOpBuffer.Enqueue(CreateProgramPtr);
            return h;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        glHandleSet IglFunc.CreateProgram(int count)
        {
            M128 m = default;
            glHandleSet h = new glHandleSet(count);
            m.Write<ulong>(0, (ulong)h.handle);
            m.Write<int>(2, count);
            frameOpBuffer.Enqueue(m);
            frameOpBuffer.Enqueue(CreateProgramSetPtr);
            return h;
        }

        glHandleSet IglFunc.CreateShaderSet(int count, ShaderType type)
        {
            glHandleSet ret = new glHandleSet(count);
            M128 m = new M128();
            m.Write<int>(0, count);
            m.Write<uint>(1, (uint)type);
            m.Write<ulong>(1, (ulong)ret.handle);
            frameOpBuffer.Enqueue(m);
            frameOpBuffer.Enqueue(CreateShaderPtr);
            return ret;
        }

        IntPtr IglFunc.CreateWindowHandle(int width, int height, string tittle, IntPtr monitor, Form share)
        {
            byte[] tittleBytes = Encoding.UTF8.GetBytes(tittle);
            IntPtr windowPtr;
            if (share == null)
            {
                windowPtr = InternalIO.glfwCreateWindow(
                    width, height, tittleBytes, monitor, IntPtr.Zero);
            }
            else
            {
                windowPtr = InternalIO.glfwCreateWindow(
                    width, height, tittleBytes, monitor, share.windowID);
            }

            if ((long)windowPtr == -1 || (long)windowPtr == -2)
            {
                throw new Exception("Cannot create window instance!");
            }
            else
            {
                return windowPtr;
            }
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        glHandle IglFunc.CreatGraphicProgram()
        {
            glHandle h = glHandle.Alloc(1);
            frameOpBuffer.Enqueue(h);
            frameOpBuffer.Enqueue(CreateProgramPtr);
            return h;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe void IglFunc.DeleteBuffer(glHandle handle)
        {
            M128 m = default;
            m.Write<ulong>(0, (ulong)handle.valuePtr);
            m.Write(2, 1);
            frameOpBuffer.Enqueue(m);
            frameOpBuffer.Enqueue(DeleBufferPtr);
        }

        unsafe void IglFunc.DeleteBuffers(glHandleSet handle)
        {
            M128 m = default;
            m.Write<ulong>(0, (ulong)handle.handle);
            m.Write<uint>(2, (uint)handle.length);
            frameOpBuffer.Enqueue(m);
            frameOpBuffer.Enqueue(DeleBufferPtr);
        }

        unsafe void IglFunc.DeleteVertexArrays(glHandleSet arrays)
        {
            M128 m = default; m.Write<ulong>(1, (ulong)arrays.handle);
            m.Write<int>(0, arrays.length);
            frameOpBuffer.Enqueue(m);
            frameOpBuffer.Enqueue(DeleteVertexArrayPtr);
        }

        void IglFunc.DrawElements(GepmetryType mode, uint count, TypeCode type, IntPtr ptr)
        {
            uint a;
            switch (type)
            {
                case TypeCode.UInt32:
                    a = GLconst.UNSIGNED_INT;
                    break;

                case TypeCode.UInt16:
                    a = GLconst.UNSIGNED_SHORT;
                    break;

                case TypeCode.Byte:
                    a = GLconst.UNSIGNED_BYTE;
                    break;

                default:
                    InternalIO.InternalWriteLog(
                        $"Parameter error in parameter {type} method DrawElements. " +
                        $"Only {TypeCode.Byte}, {TypeCode.UInt16}, {TypeCode.UInt32} types are suporrted.",
                        LogType.Error);
                    return;
            }
            frameOpBuffer.Enqueue((uint)mode, count, a);
            frameOpBuffer.Enqueue(ptr);
            frameOpBuffer.Enqueue(DrawElementsPtr);
        }

        unsafe glHandleSet IglFunc.GenBuffers(int count)
        {
            glHandleSet h = new glHandleSet(count);
            M128 m = default; m.Write<uint>(2, (uint)count); m.Write<ulong>(0, (ulong)h.handle);
            frameOpBuffer.Enqueue(m);
            frameOpBuffer.Enqueue(GenBufferPtr);
            return h;
        }

        unsafe glHandleSet IglFunc.GenTextures(int count)
        {
            glHandleSet h = new glHandleSet(count);
            M128 m = default; m.Write<uint>(2, (uint)count); m.Write<ulong>(0, (ulong)h.handle);
            frameOpBuffer.Enqueue(m);
            frameOpBuffer.Enqueue(GenTexturesPtr);
            return h;
        }

        unsafe glHandleSet IglFunc.GenVertexArrays(int count)
        {
            glHandleSet h = new glHandleSet(count);
            M128 m = default; m.Write<uint>(2, (uint)count); m.Write<ulong>(0, (ulong)h.handle);
            frameOpBuffer.Enqueue(m);
            frameOpBuffer.Enqueue(GenTexturesPtr);
            return h;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe glSHandle IglFunc.GetUniformLocation(glHandle program, string ptr)
        {
            glSHandle h = glSHandle.Alloc(0);
            M128 m = default;
            m.Write<ulong>(0, (ulong)program.Handle);
            m.Write<ulong>(1, (ulong)GCHandle.Alloc(Encoding.UTF8.GetBytes(ptr), GCHandleType.Pinned).AddrOfPinnedObject());
            frameOpBuffer.Enqueue(m);
            frameOpBuffer.Enqueue((IntPtr)h.valuePtr);
            frameOpBuffer.Enqueue(GetUniformLocationPtr);
            return h;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        bool IglFunc.GetWindowShouldClose(Form form)
        {
            return InternalIO.glfwWindowShouldClose(form.windowID) == 0;
        }

        public void GLswapBuffers(Form form)
        {
            if (form.windowID == IntPtr.Zero)
            {
                return;
            }
            InternalIO.glfwSwapBuffers(form.windowID);
        }

        void IglFunc.LoadShaderSource(glHandle shaderHandle, string codeStream)
        {
            frameOpBuffer.Enqueue(shaderHandle);
            frameOpBuffer.Enqueue(codeStream);
            frameOpBuffer.Enqueue(ShaderSourcePtr);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.MakeContexCurrent(Form form)
        {
            if (form.windowID == IntPtr.Zero)
            {
                return;
            }
            InternalIO.glfwMakeContextCurrent(form.windowID);
        }

        void IglFunc.SetBufferData<T>(BufferType bufferType, T bufferData, BufferUsage usage)
        {
            frameOpBuffer.Enqueue((uint)bufferType, (uint)usage);
            frameOpBuffer.Enqueue((IntPtr)sizeof(T));
            frameOpBuffer.Enqueue<T>(new T[] { bufferData });
            frameOpBuffer.Enqueue(BufferDataPtr);
        }

        void IglFunc.SetBufferData<T>(BufferType bufferType, T[] bufferArray, BufferUsage usage)
        {
            frameOpBuffer.Enqueue((uint)bufferType, (uint)usage);
            frameOpBuffer.Enqueue((IntPtr)(Marshal.SizeOf<T>() * bufferArray.Length));
            frameOpBuffer.Enqueue<T>(bufferArray);
            frameOpBuffer.Enqueue(BufferDataPtr);
        }

        void IglFunc.SetVertexAttribute(uint index, int size, TypeCode t, bool normalized, uint stride, int pointer)
        {
            uint type = InternalIO.GLtype[t];
            frameOpBuffer.Enqueue(index, type, stride);
            frameOpBuffer.Enqueue(size, normalized ? 1 : 0, pointer);
            frameOpBuffer.Enqueue(SetVertexArrayPtr);
        }

        //TODO:双线程，换运行环境
        void IglFunc.SwitchContext()
        {
            frameOpBuffer.context = api;
        }

        unsafe void IglFunc.TextureImage2d<T>(int target, int level, uint internalformat, uint width, uint height, uint format, uint type, glHandle pixels)
        {
            frameOpBuffer.Enqueue(pixels);
            frameOpBuffer.Enqueue((uint)level, internalformat, width, height);
            frameOpBuffer.Enqueue((uint)target, format, type);
            frameOpBuffer.Enqueue(textureImage2dPtr);
        }

        void IglFunc.TextureParameter(int target, uint pname, int param)
        {
            M128 m = default;
            m.Write<int>(0, target);
            m.Write<uint>(2, pname);
            m.Write<int>(3, param);
            frameOpBuffer.Enqueue(m);
            frameOpBuffer.Enqueue(TextureParameterPtr);
        }

        void IglFunc.UseProgram(glHandle program)
        {
            frameOpBuffer.Enqueue((IntPtr)program.valuePtr);
            frameOpBuffer.Enqueue(UseProgramPtr);
        }

        void IglFunc.Viewport(int x, int y, uint width, uint height)
        {
            Vec4d v = new Vec4d(x, y, (int)width, (int)height);
            frameOpBuffer.Enqueue(v);
            frameOpBuffer.Enqueue(ViewPortPtr);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.frameworkHandleEnqueue(IntPtr methodHandle, params M128[] param)
        {
            foreach (M128 item in param)
            {
                frameOpBuffer.Enqueue(item);
            }
            frameOpBuffer.Enqueue(methodHandle);
        }

        bool IglFunc.FrameCanUpdate
        {
            get
            {
                if (unupdatedFrame.DirectValue > 5)
                {
                    return false;
                }
                else
                {
                    *unupdatedFrame.valuePtr += 1;
                    frameOpBuffer.Enqueue((IntPtr)unupdatedFrame.valuePtr);
                    frameOpBuffer.Enqueue(CanUpdatePtr);
                    return true;
                }
            }
        }
    }
}