/*
 * Author: Andrey Pokidov
 * License: Apache-2.0
 * Date: 10 Feb 2019
 */

namespace BGC
{
    public struct Matrix2x2FP32
    {
        public float r1c1 = 0.0f, r1c2 = 0.0f;
        public float r2c1 = 0.0f, r2c2 = 0.0f;

        public Matrix2x2FP32(float d1, float d2)
        {
            this.r1c1 = d1;
            this.r2c2 = d2;
        }

        public Matrix2x2FP32(in Matrix2x2FP32 matrix)
        {
            this.r1c1 = matrix.r1c1;
            this.r1c2 = matrix.r1c2;

            this.r2c1 = matrix.r2c1;
            this.r2c2 = matrix.r2c2;
        }

        public Matrix2x2FP32(in Matrix2x2FP64 matrix)
        {
            this.r1c1 = (float)matrix.r1c1;
            this.r1c2 = (float)matrix.r1c2;

            this.r2c1 = (float)matrix.r2c1;
            this.r2c2 = (float)matrix.r2c2;
        }

        public readonly float GetDeterminant()
        {
            return this.r1c1 * this.r2c2 - this.r1c2 * this.r2c1;
        }

        public readonly bool IsSingular()
        {
            return UtilityFP32.IsZero(this.GetDeterminant());
        }

        public void Transpose()
        {
            (this.r1c2, this.r2c1) = (this.r2c1, this.r1c2);
        }

        public bool Invert()
        {
            float determinant = this.GetDeterminant();

            if (UtilityFP32.IsZero(determinant))
            {
                return false;
            }

            float r1c1 =  this.r2c2;
            float r1c2 = -this.r1c2;

            float r2c1 = -this.r2c1;
            float r2c2 =  this.r1c1;

            float multiplier = 1.0f / determinant;

            this.r1c1 = r1c1 * multiplier;
            this.r1c2 = r1c2 * multiplier;

            this.r2c1 = r2c1 * multiplier;
            this.r2c2 = r2c2 * multiplier;

            return true;
        }

        public void Reset()
        {
            this.r1c1 = 0.0f;
            this.r1c2 = 0.0f;

            this.r2c1 = 0.0f;
            this.r2c2 = 0.0f;
        }

        public void SetToIdentity()
        {
            this.r1c1 = 1.0f;
            this.r1c2 = 0.0f;

            this.r2c1 = 0.0f;
            this.r2c2 = 1.0f;
        }

        public void SetToDiagonal(float d1, float d2)
        {
            this.r1c1 = d1;
            this.r1c2 = 0.0f;

            this.r2c1 = 0.0f;
            this.r2c2 = d2;
        }

        public void Set(in Matrix2x2FP32 matrix)
        {
            this.r1c1 = matrix.r1c1;
            this.r1c2 = matrix.r1c2;

            this.r2c1 = matrix.r2c1;
            this.r2c2 = matrix.r2c2;
        }

        public void Set(in Matrix2x2FP64 matrix)
        {
            this.r1c1 = (float)matrix.r1c1;
            this.r1c2 = (float)matrix.r1c2;

            this.r2c1 = (float)matrix.r2c1;
            this.r2c2 = (float)matrix.r2c2;
        }

        public void SetTransposedOf(in Matrix2x2FP32 matrix)
        {
            this.r1c1 = matrix.r1c1;
            this.r2c2 = matrix.r2c2;
            (this.r1c2, this.r2c1) = (matrix.r2c1, matrix.r1c2);
        }

        public void SetTransposedOf(in Matrix2x2FP64 matrix)
        {
            this.r1c1 = (float)matrix.r1c1;
            this.r1c2 = (float)matrix.r2c1;

            this.r2c1 = (float)matrix.r1c2;
            this.r2c2 = (float)matrix.r2c2;
        }

        public bool SetInvertedOf(in Matrix2x2FP32 matrix)
        {
            float determinant = matrix.GetDeterminant();

            if (-UtilityFP32.EPSYLON <= determinant && determinant <= UtilityFP32.EPSYLON)
            {
                return false;
            }

            float r1c1 =  matrix.r2c2;
            float r1c2 = -matrix.r1c2;

            float r2c1 = -matrix.r2c1;
            float r2c2 =  matrix.r1c1;

            float multiplier = 1.0f / determinant;

            this.r1c1 = r1c1 * multiplier;
            this.r1c2 = r1c2 * multiplier;

            this.r2c1 = r2c1 * multiplier;
            this.r2c2 = r2c2 * multiplier;

            return true;
        }

        public void SetRow1(float c1, float c2)
        {
            this.r1c1 = c1;
            this.r1c2 = c2;
        }

        public void SetRow2(float c1, float c2)
        {
            this.r2c1 = c1;
            this.r2c2 = c2;
        }

        public void SetColumn1(float r1, float r2)
        {
            this.r1c1 = r1;
            this.r2c1 = r2;
        }

        public void SetColumn2(float r1, float r2)
        {
            this.r1c2 = r1;
            this.r2c2 = r2;
        }

        public void AppendScaled(in Matrix2x2FP32 matrix, float scale)
        {
            this.r1c1 += matrix.r1c1 * scale;
            this.r1c2 += matrix.r1c2 * scale;

            this.r2c1 += matrix.r2c1 * scale;
            this.r2c2 += matrix.r2c2 * scale;
        }

        public static void Add(in Matrix2x2FP32 matrix1, in Matrix2x2FP32 matrix2, out Matrix2x2FP32 result)
        {
            result.r1c1 = matrix1.r1c1 + matrix2.r1c1;
            result.r1c2 = matrix1.r1c2 + matrix2.r1c2;

            result.r2c1 = matrix1.r2c1 + matrix2.r2c1;
            result.r2c2 = matrix1.r2c2 + matrix2.r2c2;
        }

        public static void Subtract(in Matrix2x2FP32 minuend, in Matrix2x2FP32 subtrahend, out Matrix2x2FP32 difference)
        {
            difference.r1c1 = minuend.r1c1 - subtrahend.r1c1;
            difference.r1c2 = minuend.r1c2 - subtrahend.r1c2;

            difference.r2c1 = minuend.r2c1 - subtrahend.r2c1;
            difference.r2c2 = minuend.r2c2 - subtrahend.r2c2;
        }

        public static void Multiply(in Matrix2x2FP32 multiplicand, float multiplier, out Matrix2x2FP32 product)
        {
            product.r1c1 = multiplicand.r1c1 * multiplier;
            product.r1c2 = multiplicand.r1c2 * multiplier;

            product.r2c1 = multiplicand.r2c1 * multiplier;
            product.r2c2 = multiplicand.r2c2 * multiplier;
        }

        public static void Divide(in Matrix2x2FP32 dividend, float divisor, out Matrix2x2FP32 quotient)
        {
            Multiply(dividend, 1.0f / divisor, out quotient);
        }

        public static void GetRightProduct(in Matrix2x2FP32 matrix, in Vector2FP32 vector, out Vector2FP32 result)
        {
            float x1 = matrix.r1c1 * vector.x1 + matrix.r1c2 * vector.x2;
            float x2 = matrix.r2c1 * vector.x1 + matrix.r2c2 * vector.x2;

            result.x1 = x1;
            result.x2 = x2;
        }

        public static void GetLeftProduct(in Vector2FP32 vector, in Matrix2x2FP32 matrix, out Vector2FP32 result)
        {
            float x1 = vector.x1 * matrix.r1c1 + vector.x2 * matrix.r2c1;
            float x2 = vector.x1 * matrix.r1c2 + vector.x2 * matrix.r2c2;

            result.x1 = x1;
            result.x2 = x2;
        }

        public static void LoadZero(out Matrix2x2FP32 matrix)
        {
            matrix.r1c1 = 0.0f;
            matrix.r1c2 = 0.0f;

            matrix.r2c1 = 0.0f;
            matrix.r2c2 = 0.0f;
        }

        public static void LoadIdentity(out Matrix2x2FP32 matrix)
        {
            matrix.r1c1 = 1.0f;
            matrix.r1c2 = 0.0f;

            matrix.r2c1 = 0.0f;
            matrix.r2c2 = 1.0f;
        }

        public static void LoadDiagonal(float d1, float d2, out Matrix2x2FP32 matrix)
        {
            matrix.r1c1 = d1;
            matrix.r1c2 = 0.0f;

            matrix.r2c1 = 0.0f;
            matrix.r2c2 = d2;
        }
    }
}