using StgSharp.Logic;
using StgSharp.Math;

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Text;

namespace StgSharp.Graphics
{
    internal unsafe partial class GLonRender : IglFunc
    {
        internal GLcontext* api;
        private FrameTimeoutException refreshSIgnal = new FrameTimeoutException();

        internal GLonRender(GLcontext* context)
        {
            api = context;
        }

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

        void IglFunc.SwitchContext()
        {
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.ActiveTexture(uint type)
        {
            api->glActiveTexture(type);
        }

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

        void IglFunc.AlignFrame(Form form)
        {
            if (form.timer.alignSign.byte0 > 0)
            {
                throw new InvalidOperationException();
            }
            form.timer.alignSign.byte0++;
            form.timer.WaitNextFrame();
            throw refreshSIgnal;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.AttachShader(glHandle program, glHandle shader)
        {
            api->glAttachShader(*program.valuePtr, shader.DirectValue);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.BindBuffer(BufferType bufferType, glHandle handle)
        {
            api->glBindBuffer((uint)bufferType, handle.DirectValue);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.BindTexture(uint type, glHandle texture)
        {
            api->glBindTexture(type, texture.DirectValue);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.BindVertexArray(glHandle handle)
        {
            api->glBindVertexArray(handle.Value);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.Clear(MaskBufferBit mask)
        {
            api->glClear((uint)mask);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe void IglFunc.ClearColor(float R, float G, float B, float A)
        {
            api->glClearColor(R, G, B, A);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe void IglFunc.ClearGraphicError()
        {
            while (api->glGetError() != 0) { }
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe void IglFunc.LoadShaderSource(glHandle shaderHandle, string codeStream)
        {
            byte[] stream = Encoding.UTF8.GetBytes(codeStream);
            fixed (byte* streamPtr = stream)
            {
                api->glShaderSource(shaderHandle.DirectValue, 1, &streamPtr, (void*)0);
            }
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        glHandleSet IglFunc.CreateShaderSet(int count, ShaderType type)
        {
            glHandleSet ret = new glHandleSet(count);
            uint t = (uint)type;
            for (int i = 0; i < count; i++)
            {
                uint id = api->glCreateShader(t);
                if (id == 0)
                {
                    uint error = api->glGetError();
                    InternalIO.InternalWriteLog($"Failed in creating shader: {error}", LogType.Error);
                    throw new Exception();
                }
                ret.SetValue(i, id);
            }
            return ret;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.CompileShader(glHandle shaderhandle)
        {
            api->glCompileShader(shaderhandle.DirectValue);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        glHandle IglFunc.CreateProgram()
        {
            return glHandle.Alloc(api->glCreateProgram());
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe glHandleSet IglFunc.CreateProgram(int count)
        {
            glHandleSet h = new glHandleSet(count);
            for (int i = 0; i < count; i++)
            {
                h.SetValue(i, api->glCreateProgram());
            }
            return h;
        }

        unsafe 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)]
        unsafe glHandle IglFunc.CreatGraphicProgram()
        {
            return glHandle.Alloc(api->glCreateProgram());
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe void IglFunc.DeleteBuffer(glHandle handle)
        {
            api->glDeleteBuffers(1, (uint*)handle.Handle);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe void IglFunc.DeleteBuffers(glHandleSet handle)
        {
            api->glDeleteBuffers((uint)handle.length, (uint*)handle.handle);
            handle.Free();
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe void IglFunc.DeleteVertexArrays(glHandleSet arrays)
        {
            api->glDeleteVertexArrays((uint)arrays.length, (uint*)arrays.handle);
            arrays.Free();
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe 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 {nameof(type)} method DrawElements. " +
                        $"Only {typeof(uint).Name},{typeof(ushort).Name},{typeof(byte).Name} types are suporrted.",
                        LogType.Error);
                    return;
            }
            api->glDrawElements((uint)mode, count, a, (void*)ptr);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe glHandleSet IglFunc.GenBuffers(int count)
        {
            glHandleSet h = new glHandleSet((int)count);
            api->glGenBuffers((uint)count, h.handle);
            return h;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe glHandleSet IglFunc.GenTextures(int count)
        {
            glHandleSet h = new glHandleSet((int)count);
            api->glGenTextures((uint)count, h.handle);
            return h;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe glHandleSet IglFunc.GenVertexArrays(int count)
        {
            glHandleSet h = new glHandleSet(count);
            api->glGenVertexArrays((uint)count, h.handle);
            return h;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe glSHandle IglFunc.GetUniformLocation(glHandle program, string name)
        {
            byte[] code = Encoding.UTF8.GetBytes(name);
            fixed (byte* ptr = code)
            {
                return glSHandle.Alloc(api->glGetUniformLocation(program.DirectValue, ptr));
            }
        }

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

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe void IglFunc.MakeContexCurrent(Form form)
        {
            if (form.windowID == IntPtr.Zero)
            {
                InternalIO.InternalWriteLog($"From {nameof(form)} is not initted.", LogType.Warning);
                return;
            }
            InternalIO.glfwMakeContextCurrent(form.windowID);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe void IglFunc.SetBufferData<T>(BufferType bufferType, T bufferData, BufferUsage usage)
        {
            int size = sizeof(T);
            api->glBufferData(
                (uint)bufferType,
                (IntPtr)size,
                (IntPtr)(&bufferData),
                (uint)usage);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        unsafe void IglFunc.SetBufferData<T>(BufferType bufferType, T[] bufferArray, BufferUsage usage)
        {
            int size = bufferArray.Length * Marshal.SizeOf(typeof(T));
            if (bufferArray == null)
            {
                return;
            }
            fixed (void* bufferPtr = bufferArray)
                api->glBufferData(
                    (uint)bufferType,
                    (IntPtr)size,
                    (IntPtr)bufferPtr,
                    (uint)usage);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.SetVertexAttribute(uint index, int size, TypeCode t, bool normalized, uint stride, int pointer)
        {
            uint type = InternalIO.GLtype[t];
            api->glVertexAttribPointer(index, size, type, normalized ? 1 : 0, stride, (void*)pointer);
            api->glEnableVertexAttribArray(index);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.TextureImage2d<T>(int target, int level, uint internalformat, uint width, uint height, uint format, uint type, glHandle pixels)
        {
            api->glTexImage2D(
                (uint)target, level, internalformat, width, height, 0, format, type, pixels.valuePtr
                );
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.TextureParameter(int target, uint pname, int param)
        {
            api->glTexParameteri((uint)target, pname, param);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.UseProgram(glHandle program)
        {
            api->glUseProgram(program.DirectValue);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void IglFunc.Viewport(int x, int y, uint width, uint height)
        {
            api->glViewport(x, y, width, height);
        }
    }
}