using System;
using System.Numerics;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

namespace StgSharp.Math
{
    [StructLayout(LayoutKind.Explicit, Size = 5 * 4 * sizeof(float) + sizeof(bool), Pack = 16)]
    public struct Matrix3x2
    {
        [FieldOffset(0)] internal Mat2 mat;
        [FieldOffset(2 * 4 * sizeof(float))] internal Mat3 transpose;
        [FieldOffset(5 * 4 * sizeof(float))] internal bool isTransposed;


        public Matrix3x2(
            float a00, float a01,
            float a10, float a11,
            float a20, float a21
            )
        {
            mat.colum0 = new Vector4(a00, a10, a20, 0);
            mat.colum0 = new Vector4(a01, a11, a21, 0);
        }

        internal Matrix3x2(
            Vector4 c0,
            Vector4 c1
            )
        {
            mat.colum0 = c0;
            mat.colum1 = c1;
        }

        public unsafe float this[int rowNum, int columNum]
        {
            get
            {
                if (rowNum > 2 || rowNum < 0)
                {
                    throw new ArgumentOutOfRangeException(nameof(columNum));
                }
                if (columNum > 1 || columNum < 0)
                {
                    throw new ArgumentOutOfRangeException(nameof(columNum));
                }
                InternalTranspose();
                fixed (float* p = &this.transpose.m00)
                {
                    ulong pbit = (ulong)p
                        + (ulong)sizeof(Vector4) * (ulong)rowNum
                        + (ulong)sizeof(float) * (ulong)columNum;
                    return *(float*)pbit;
                }
            }
            set
            {
                if (rowNum > 2 || rowNum < 0)
                {
                    throw new ArgumentOutOfRangeException(nameof(columNum));
                }
                if (columNum > 1 || columNum < 0)
                {
                    throw new ArgumentOutOfRangeException(nameof(columNum));
                }
                InternalTranspose();
                fixed (float* p = &this.transpose.m00)
                {
                    ulong pbit = (ulong)p
                        + (ulong)sizeof(Vector4) * (ulong)rowNum
                        + (ulong)sizeof(float) * (ulong)columNum;
                    *(float*)pbit = value;
                }
                isTransposed = false;
            }
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        internal unsafe void InternalTranspose()
        {
            if (!isTransposed)
            {
                fixed (Mat2* source = &this.mat)
                fixed (Mat3* target = &this.transpose)
                {
                    InternalIO.Transpose2to3_internal(source, target);
                }
                isTransposed = true;
            }
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Matrix3x2 operator +(Matrix3x2 left, Matrix3x2 right)
        {
            return new Matrix3x2(
                left.mat.colum0 + right.mat.colum0,
                left.mat.colum1 + right.mat.colum1
                );
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Matrix3x2 operator -(Matrix3x2 left, Matrix3x2 right)
        {
            return new Matrix3x2(
                left.mat.colum0 - right.mat.colum0,
                left.mat.colum1 - right.mat.colum1
                );
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Matrix3x2 operator *(Matrix3x2 mat, float value)
        {
            return new Matrix3x2(
                mat.mat.colum0 * value,
                mat.mat.colum1 * value
                );
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Matrix3x2 operator /(Matrix3x2 mat, float value)
        {
            return new Matrix3x2(
                mat.mat.colum0 / value,
                mat.mat.colum1 / value
                );
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Matrix3x2 operator *(Matrix3x2 left, Matrix2x2 right)
        {
            left.InternalTranspose();
            return new Matrix3x2(
                Vector4.Dot(left.transpose.colum0, right.mat.colum0),
                Vector4.Dot(left.transpose.colum0, right.mat.colum1),

                Vector4.Dot(left.transpose.colum1, right.mat.colum0),
                Vector4.Dot(left.transpose.colum1, right.mat.colum1),

                Vector4.Dot(left.transpose.colum2, right.mat.colum0),
                Vector4.Dot(left.transpose.colum2, right.mat.colum1)
                );
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Matrix3x3 operator *(Matrix3x2 left, Matrix2x3 right)
        {
            left.InternalTranspose();
            return new Matrix3x3(
                Vector4.Dot(left.transpose.colum0, right.mat.colum0),
                Vector4.Dot(left.transpose.colum0, right.mat.colum1),
                Vector4.Dot(left.transpose.colum0, right.mat.colum2),

                Vector4.Dot(left.transpose.colum1, right.mat.colum0),
                Vector4.Dot(left.transpose.colum1, right.mat.colum1),
                Vector4.Dot(left.transpose.colum1, right.mat.colum2),

                Vector4.Dot(left.transpose.colum2, right.mat.colum0),
                Vector4.Dot(left.transpose.colum2, right.mat.colum1),
                Vector4.Dot(left.transpose.colum2, right.mat.colum2)
                );
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Matrix3x4 operator *(Matrix3x2 left, Matrix2x4 right)
        {
            left.InternalTranspose();
            return new Matrix3x4(
                Vector4.Dot(left.transpose.colum0, right.mat.colum0),
                Vector4.Dot(left.transpose.colum0, right.mat.colum1),
                Vector4.Dot(left.transpose.colum0, right.mat.colum2),
                Vector4.Dot(left.transpose.colum0, right.mat.colum3),

                Vector4.Dot(left.transpose.colum1, right.mat.colum0),
                Vector4.Dot(left.transpose.colum1, right.mat.colum1),
                Vector4.Dot(left.transpose.colum1, right.mat.colum2),
                Vector4.Dot(left.transpose.colum1, right.mat.colum3),

                Vector4.Dot(left.transpose.colum2, right.mat.colum0),
                Vector4.Dot(left.transpose.colum2, right.mat.colum1),
                Vector4.Dot(left.transpose.colum2, right.mat.colum2),
                Vector4.Dot(left.transpose.colum2, right.mat.colum3)
                );
        }


    }
}