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

namespace StgSharp.Math
{
    [StructLayout(LayoutKind.Explicit)]
    public struct Array2x2:IEquatable<Array2x2>
    {
        [FieldOffset(0)]
        public Vec2D row1;
        [FieldOffset(8)]
        public Vec2D row2;

        public Array2x2(Vec2D c0, Vec2D c1)
        {
            row1 = c0;
            row2 = c1;
        }

        public Array2x2(
            float a11,
            float a12,
            float a21,
            float a22
            )
        {
            row1 = new Vec2D(a11, a12);
            row2 = new Vec2D(a21, a22);
        }

        bool IEquatable<Array2x2>.Equals(Array2x2 other)
        {
            if (this.GetHashCode() != other.GetHashCode())
            {
                return false;
            }
            else
            {
                return
                    this.row1 == other.row1
                    && this.row2 == other.row2;
            }
        }

        public override bool Equals(object obj)
        {
            if (obj == null)
            {
                return false;
            }
            else if (obj.GetType() != typeof(Array2x2))
            {
                return false;
            }
            else
            {
                return this.Equals((Vec3D)obj);
            }
        }

        public static unsafe Array2x2 operator *(Array2x2 array1, Array2x2 array2)
        {
            float* p = &array1.row1.X;

            Vec2D colum1 = new Vec2D(
                *p , *(p + 2)
                );
            Vec2D colum2 = new Vec2D(
                *(p + 1), *(p + 3)
                );

            return new Array2x2(
                colum1 * array2.row1,
                colum2 * array2.row1,
                colum1 * array2.row2,
                colum2 * array2.row2
                );
        }

        public static Array2x2 operator +(Array2x2 array1, Array2x2 array2)
        {
            return new Array2x2(
                array1.row1 + array2.row1,
                array1.row2 + array2.row2
                );
        }

        public static Array2x2 operator -(Array2x2 array1, Array2x2 array2)
        {
            return new Array2x2(
                array1.row1 - array2.row1,
                array1.row2 - array2.row2
                );
        }

        
    }
}