#include "Catch2.h"
#include <Eule/Matrix4x4.h>
#include <Eule/Vector3.h>
#include "../_TestingUtilities/HandyMacros.h"
#include <random>

using namespace Eule;

namespace {
    static std::mt19937 rng = std::mt19937((std::random_device())());
}

// Tests that a freshly created matrix is an identity matrix
TEST_CASE(__FILE__"/New_Matrix_Is_Identity", "[Matrix4x4]")
{
    Matrix4x4 mat;

    for (std::size_t i = 0; i < 4; i++)
        for (std::size_t j = 0; j < 4; j++)
            if (i == j)
               REQUIRE(mat[i][j] == 1.0);
            else
               REQUIRE(mat[i][j] == 0.0);

    return;
}

// Test if setting values via array descriptors works
TEST_CASE(__FILE__"/Can_Set_Values_ArrayDescriptor", "[Matrix4x4]")
{
    Matrix4x4 mat;
    mat[0][0] = 1;
    mat[0][1] = 2;
    mat[0][2] = 3;
    mat[0][3] = 4;
    mat[1][0] = 5;
    mat[1][1] = 6;
    mat[1][2] = 7;
    mat[1][3] = 8;
    mat[2][0] = 9;
    mat[2][1] = 10;
    mat[2][2] = 11;
    mat[2][3] = 12;
    mat[3][0] = 13;
    mat[3][1] = 14;
    mat[3][2] = 15;
    mat[3][3] = 16;

    for (std::size_t i = 0; i < 4; i++)
        for (std::size_t j = 0; j < 4; j++)
           REQUIRE((double)(i * 4 + j + 1) == mat[i][j]);

    return;
}

// Tests if setting values via letters works
TEST_CASE(__FILE__"/Can_Set_Values_Letters", "[Matrix4x4]")
{
    Matrix4x4 mat;
    mat.a = 1;
    mat.b = 2;
    mat.c = 3;
    mat.d = 4;
    mat.e = 5;
    mat.f = 6;
    mat.g = 7;
    mat.h = 8;
    mat.i = 9;
    mat.j = 10;
    mat.k = 11;
    mat.l = 12;
    mat.m = 13;
    mat.n = 14;
    mat.o = 15;
    mat.p = 16;

    for (std::size_t i = 0; i < 4; i++)
        for (std::size_t j = 0; j < 4; j++)
           REQUIRE((double)(i * 4 + j + 1) == mat[i][j]);

    return;
}

// Tests if setting values via multiple initializer lists works
TEST_CASE(__FILE__"/Can_Set_Values_Multiple_Initializer_Lists", "[Matrix4x4]")
{
    Matrix4x4 mat;
    mat[0] = {  1,  2,  3,  4 };
    mat[1] = {  5,  6,  7,  8 };
    mat[2] = {  9, 10, 11, 12 };
    mat[3] = { 13, 14, 15, 16 };

    for (std::size_t i = 0; i < 4; i++)
        for (std::size_t j = 0; j < 4; j++)
           REQUIRE((double)(i * 4 + j + 1) == mat[i][j]);

    return;
}

// Tests if values can be read correctly from the reference variables
TEST_CASE(__FILE__"/Can_Read_Letters", "[Matrix4x4]")
{
    Matrix4x4 mat;

    // Populate matrix
    for (std::size_t i = 0; i < 4; i++)
        for (std::size_t j = 0; j < 4; j++)
            mat[i][j] = (double)(i * 4 + j + 1);

    // Check if values can be read
   REQUIRE(mat.a ==  1.0);
   REQUIRE(mat.b ==  2.0);
   REQUIRE(mat.c ==  3.0);
   REQUIRE(mat.d ==  4.0);
   REQUIRE(mat.e ==  5.0);
   REQUIRE(mat.f ==  6.0);
   REQUIRE(mat.g ==  7.0);
   REQUIRE(mat.h ==  8.0);
   REQUIRE(mat.i ==  9.0);
   REQUIRE(mat.j == 10.0);
   REQUIRE(mat.k == 11.0);
   REQUIRE(mat.l == 12.0);
   REQUIRE(mat.m == 13.0);
   REQUIRE(mat.n == 14.0);
   REQUIRE(mat.o == 15.0);
   REQUIRE(mat.p == 16.0);

    return;
}

// Tests if the copy constructor results in the same values as the reference given
TEST_CASE(__FILE__"/CopyConstructor_Equal_Values", "[Matrix4x4]")
{
    Matrix4x4 mat1;

    // Fill with values
    for (std::size_t i = 0; i < 4; i++)
        for (std::size_t j = 0; j < 4; j++)
            mat1[i][j] = i * 4.0 + j;

    // Copy
    Matrix4x4 mat2(mat1);

    // Both equal?
    for (std::size_t i = 0; i < 4; i++)
        for (std::size_t j = 0; j < 4; j++)
           REQUIRE(mat1[i][j] == mat2[i][j]);

    return;
}

// Tests if the equals operator results in the same values as the reference given
TEST_CASE(__FILE__"/Copy_Via_Equals_Operator", "[Matrix4x4]")
{
    Matrix4x4 mat1;

    // Fill with values
    for (std::size_t i = 0; i < 4; i++)
        for (std::size_t j = 0; j < 4; j++)
            mat1[i][j] = i * 4.0 + j;

    // Copy
    Matrix4x4 mat2 = mat1;

    // Both equal?
    for (std::size_t i = 0; i < 4; i++)
        for (std::size_t j = 0; j < 4; j++)
           REQUIRE(mat1[i][j] == mat2[i][j]);

    return;
}

// Tests if the values of a matrix constructed via a copy constructor can be changed without modifying the object copied from
TEST_CASE(__FILE__"/Copy_Is_Independent_CopyConstructor", "[Matrix4x4]")
{
    Matrix4x4 mat1;

    // Fill with values
    for (std::size_t i = 0; i < 4; i++)
        for (std::size_t j = 0; j < 4; j++)
            mat1[i][j] = i * 4.0 + j;

    // Copy
    Matrix4x4 mat2(mat1);

    // Change values in mat2
    for (std::size_t i = 0; i < 4; i++)
        for (std::size_t j = 0; j < 4; j++)
            mat2[i][j] *= -99;

    // Is mat1 untouched?
    for (std::size_t i = 0; i < 4; i++)
        for (std::size_t j = 0; j < 4; j++)
           REQUIRE((double)(i * 4 + j) == mat1[i][j]);

    // Are the values of mat2 correct?
    for (std::size_t i = 0; i < 4; i++)
        for (std::size_t j = 0; j < 4; j++)
           REQUIRE((double)(i * 4 + j) * -99 == mat2[i][j]);

    return;
}

// Tests if the values of a matrix constructed copied via the equals operator can be changed without modifying the object copied from
TEST_CASE(__FILE__"/Copy_Is_Independent_EqualOperator", "[Matrix4x4]")
{
    Matrix4x4 mat1;

    // Fill with values
    for (std::size_t i = 0; i < 4; i++)
        for (std::size_t j = 0; j < 4; j++)
            mat1[i][j] = i * 4.0 + j;

    // Copy
    Matrix4x4 mat2 = mat1;

    // Change values in mat2
    for (std::size_t i = 0; i < 4; i++)
        for (std::size_t j = 0; j < 4; j++)
            mat2[i][j] *= -99;

    // Is mat1 untouched?
    for (std::size_t i = 0; i < 4; i++)
        for (std::size_t j = 0; j < 4; j++)
           REQUIRE((double)(i * 4 + j) == mat1[i][j]);

    // Are the values of mat2 correct?
    for (std::size_t i = 0; i < 4; i++)
        for (std::size_t j = 0; j < 4; j++)
           REQUIRE((double)(i * 4 + j) * -99 == mat2[i][j]);

    return;
}

// Tests that copying via operator= works
TEST_CASE(__FILE__"/Copy_Operator", "[Matrix4x4]")
{
    // Setup
    Matrix4x4 a;
    a[0] = { 1, 0, 0, 5 };
    a[1] = { 2, 0, 0, 6 };
    a[2] = { 3, 0, 0, 7 };
    a[3] = { 4, 0, 0, 8 };

    Matrix4x4 a_toCopy;
    a_toCopy[0] = { 1, 0, 0, 5 };
    a_toCopy[1] = { 2, 0, 0, 6 };
    a_toCopy[2] = { 3, 0, 0, 7 };
    a_toCopy[3] = { 4, 0, 0, 8 };

    // Exercise
    Matrix4x4 b = a_toCopy;

    // Verify
    INFO("a got destroyed!");
    REQUIRE(a == a_toCopy);

    INFO("a does not match b!");
    REQUIRE(b == a);

    return;
}

// Tests that moving via operator= works
TEST_CASE(__FILE__"/Move_Operator", "[Matrix4x4]")
{
    // Setup
    Matrix4x4 a;
    a[0] = { 1, 0, 0, 5 };
    a[1] = { 2, 0, 0, 6 };
    a[2] = { 3, 0, 0, 7 };
    a[3] = { 4, 0, 0, 8 };

    Matrix4x4 a_backup = a;

    // Exercise
    Matrix4x4 b = std::move(a);

    // Verify
    INFO("Values don't match!");
    REQUIRE(b == a_backup);

    return;
}

// Tests if the multiply-equals (*=) operator works as intended
TEST_CASE(__FILE__"/Multiplication_Equals", "[Matrix4x4]")
{
    // Populate 1
    Matrix4x4 mat1;
    mat1[0] = { 12, 33, 43, 34 };
    mat1[1] = {  0,  4,  3, 11 };
    mat1[2] = { 76,  5, 42,  4 };
    mat1[3] = {  0,  0,  0,  1 };

    // Populate 2
    Matrix4x4 mat2;
    mat2[0] = { 32, 11, 23,  6 };
    mat2[1] = { 54, 23, 64,  9 };
    mat2[2] = { 64, 43, 12, 16 };
    mat2[3] = {  0,  0,  0,  1 };


    // Multiply
    mat1 *= mat2;

    // Check
    Matrix4x4 expected;
    expected[0] = { 4918.0, 2740.0, 2904.0, 40 };
    expected[1] = {  408.0,  221.0,  292.0, 20 };
    expected[2] = { 5390.0, 2757.0, 2572.0, 20 };
    expected[3] = {      0,      0,      0,  1 };

    REQUIRE(mat1.v == expected.v);

    return;
}

// Tests if the multiplication operator works as intended
TEST_CASE(__FILE__"/Multiplication", "[Matrix4x4]")
{
    // Populate 1
    Matrix4x4 mat1;
    mat1[0] = { 12, 33, 43, 34 };
    mat1[1] = { 0,  4,  3, 11 };
    mat1[2] = { 76,  5, 42,  4 };
    mat1[3] = { 0,  0,  0,  1 };

    // Populate 2
    Matrix4x4 mat2;
    mat2[0] = { 32, 11, 23,  6 };
    mat2[1] = { 54, 23, 64,  9 };
    mat2[2] = { 64, 43, 12, 16 };
    mat2[3] = { 0,  0,  0,  1 };

    // Multiply
    Matrix4x4 mat3 = mat1 * mat2;

    // Check
    Matrix4x4 expected;
    expected[0] = { 4918.0, 2740.0, 2904.0, 40 };
    expected[1] = { 408.0,  221.0,  292.0, 20 };
    expected[2] = { 5390.0, 2757.0, 2572.0, 20 };
    expected[3] = { 0,      0,      0,  1 };

    REQUIRE(mat3.v == expected.v);

    return;
}

// Tests if GetTranslationComponent returns the correct values
TEST_CASE(__FILE__"/GetTranslationComponent", "[Matrix4x4]")
{
    // Create and populate mat
    Matrix4x4 mat;
    mat.d = 69;
    mat.h = 32;
    mat.l = 16;

    // Get translation component
    Vector3d translation = mat.GetTranslationComponent();

    // Check
    REQUIRE(translation.x == 69.0);
    REQUIRE(translation.y == 32.0);
    REQUIRE(translation.z == 16.0);

    return;
}

// Tests if SetTranslationComponent returns the correct values
TEST_CASE(__FILE__"/SetTranslationComponent", "[Matrix4x4]")
{
    // Create and populate mat
    Vector3d translation(69, 32, 16);

    // Set translation component
    Matrix4x4 mat;
    mat.SetTranslationComponent(translation);

    // Check
    REQUIRE(mat.d == 69.0);
    REQUIRE(mat.h == 32.0);
    REQUIRE(mat.l == 16.0);

    return;
}

// Tests that transpose3x3 works
TEST_CASE(__FILE__"/Transpose3x3", "[Matrix4x4]")
{
    Matrix4x4 m;
    m[0] = { 0, 0, 0, 0 };
    m[1] = { 3, 0, 4, 0 };
    m[2] = { 0, 0, 2, 5 };
    m[3] = { 9, 0, 6, 0 };

    Matrix4x4 target;
    target[0] = { 0, 3, 0, 0 };
    target[1] = { 0, 0, 0, 0 };
    target[2] = { 0, 4, 2, 5 };
    target[3] = { 9, 0, 6, 0 };

    // Create debug output
    INFO(
        "Actual: " << m.Transpose3x3() << '\n'
        << "Target: " << target << '\n'
    );

    REQUIRE(target == m.Transpose3x3());

    return;
}

// Tests that transpose4x4 works
TEST_CASE(__FILE__"/Transpose4x4", "[Matrix4x4]")
{
    Matrix4x4 m;
    m[0] = { 0, 0, 0, 0 };
    m[1] = { 3, 0, 4, 0 };
    m[2] = { 0, 0, 2, 5 };
    m[3] = { 9, 0, 6, 0 };

    Matrix4x4 target;
    target[0] = { 0, 3, 0, 9 };
    target[1] = { 0, 0, 0, 0 };
    target[2] = { 0, 4, 2, 6 };
    target[3] = { 0, 0, 5, 0 };

    // Create debug output
    INFO(
        "Actual: " << m.Transpose4x4() << '\n'
        << "Target: " << target << '\n'
    );

    REQUIRE(target == m.Transpose4x4());

    return;
}

// Tests that IsInvertible3x3 works -> true
TEST_CASE(__FILE__"/Is_Invertible_3x3_True", "[Matrix4x4]")
{
    Matrix4x4 m;
    m[0] = { 0.56601, -0.87207, 0.52783, 488.00000 };
    m[1] = { -0.55281, 0.41590, 0.85470, 500.00000 };
    m[2] = { -1.09497, -0.66076, -0.15866, -155.09390 };
    m[3] = { 0.00000, 0.00000, 0.00000, 0.00000 };

    REQUIRE(m.IsInversible3x3());

    return;
}

// Tests that IsInvertible3x3 works -> false
TEST_CASE(__FILE__"/Is_Invertible_3x3_False", "[Matrix4x4]")
{
    Matrix4x4 m;
    m[0] = { 0, 0, 1, 0 };
    m[1] = { 0, 0, 0, 0 };
    m[2] = { 0, 0, 0, 0 };
    m[3] = { 0, 0, 0, 0 };

    REQUIRE_FALSE(m.IsInversible3x3());

    return;
}

// Tests that IsInvertible4x4 works -> true
TEST_CASE(__FILE__"/Is_Invertible_4x4_True", "[Matrix4x4]")
{
    Matrix4x4 m;
    m[0] = { 0.56601, -0.87207, 0.52783, 488.00000 };
    m[1] = { -0.55281, 0.41590, 0.85470, 500.00000 };
    m[2] = { -1.09497, -0.66076, -0.15866, -155.09390 };
    m[3] = { 0.00000, 0.00000, 0.00000, 1.00000 };

    REQUIRE(m.IsInversible4x4());

    return;
}

// Tests that IsInvertible4x4 works -> false
TEST_CASE(__FILE__"/Is_Invertible_4x4_False", "[Matrix4x4]")
{
    Matrix4x4 m;
    m[0] = { 0.56601, -0.87207, 0.52783, 488.00000 };
    m[1] = { -0.55281, 0.41590, 0.85470, 500.00000 };
    m[2] = { -1.09497, -0.66076, -0.15866, -155.09390 };
    m[3] = { 0.00000, 0.00000, 0.00000, 0.00000 };

    REQUIRE_FALSE(m.IsInversible4x4());

    return;
}

// Tests that inverting a 3x3 matrix (scale, rotation, translation) works
TEST_CASE(__FILE__"/Inverse3x3", "[Matrix4x4]")
{
    // Invert 50 randomly generated matrices
    for (std::size_t i = 0; i < 50;)
    {
        Matrix4x4 m;
        m[0] = { LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE };
        m[1] = { LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE };
        m[2] = { LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE };
        m[3] = { LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE };

        if (m.IsInversible3x3())
        {
            Matrix4x4 inv_m = m.Inverse3x3();
            Matrix4x4 result = m * inv_m;

            // Create debug output
            INFO(
                "i: " << i << '\n'
                << "Actual: " << result << '\n'
                << "Target: " << Matrix4x4() << '\n'
            );

            REQUIRE(result.Similar(Matrix4x4())); // Default constructor is identity matrix
            i++;
        }
    }

    return;
}

// Tests that inverting a 4x4 matrix works
TEST_CASE(__FILE__"/Inverse4x4", "[Matrix4x4]")
{
    // Invert 50 randomly generated matrices
    for (std::size_t i = 0; i < 50;)
    {
        Matrix4x4 m;
        m[0] = { LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE };
        m[1] = { LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE };
        m[2] = { LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE };
        m[3] = { LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE, LARGE_RAND_DOUBLE };

        if (m.IsInversible4x4())
        {
            Matrix4x4 inv_m = m.Inverse4x4();

            // Create debug output
            INFO(
                "i: " << i << '\n'
                << "Actual: " << m.Multiply4x4(inv_m) << '\n'
                << "Target: " << Matrix4x4() << '\n'
            );

            REQUIRE((m.Multiply4x4(inv_m)).Similar(Matrix4x4(), 0.0001)); // Default constructor is identity matrix
            i++;
        }
    }

    return;
}

// Tests the Multiply4x4 method, which does an actual 4x4 multiplication
TEST_CASE(__FILE__"/Multiply4x4", "[Matrix4x4]")
{
    Matrix4x4 a;
    a[0] = { 0, 1, 2, 3 };
    a[1] = { 4, 5, 6, 7 };
    a[2] = { 8, 9, 0, 1 };
    a[3] = { 2, 3, 4, 5 };

    Matrix4x4 b;
    b[0] = { 9, 8, 7, 6 };
    b[1] = { 5, 4, 3, 2 };
    b[2] = { 1, 0, 9, 8 };
    b[3] = { 7, 6, 5, 4 };

    Matrix4x4 e; // Expected
    e[0] = {  28,  22,  36, 30 };
    e[1] = { 116,  94, 132, 110 };
    e[2] = { 124, 106,  88, 70 };
    e[3] = {  72,  58,  84, 70 };

    // Create debug output
    INFO(
        "Actual: " << a.Multiply4x4(b) << '\n'
        << "Target: " << e << '\n'
    );

    REQUIRE(a.Multiply4x4(b).Similar(e));
}

// Tests the DropTranslationComponents method. It should return itself, with d,h,l = 0,0,0
TEST_CASE(__FILE__"/DropTranslationComponents", "[Matrix4x4]")
{
    // Setup
    Matrix4x4 a;
    a[0] = { 0, 1, 2, 3 };
    a[1] = { 4, 5, 6, 7 };
    a[2] = { 8, 9, 0, 1 };
    a[3] = { 2, 3, 4, 5 };

    Matrix4x4 e; // Expected
    e[0] = { 0, 1, 2, 0 };
    e[1] = { 4, 5, 6, 0 };
    e[2] = { 8, 9, 0, 0 };
    e[3] = { 2, 3, 4, 5 };

    // Exercise, Verify
    REQUIRE(e == a.DropTranslationComponents());
    return;
}

//! Tests that adding two matrices works as intended
TEST_CASE(__FILE__"/Operator_Add", "[Matrix4x4]")
{
    // Setup
    Matrix4x4 a;
    a[0] = { -9, 5, 6, 7 };
    a[1] = {  1,  2, 5, 0 };
    a[2] = {  2, -2, 7, 5 };
    a[3] = {  3,  0, 3, 0 };

    Matrix4x4 b;
    b[0] = { 6, 0, 5, 0 };
    b[1] = { 3, 0, 1, 1 };
    b[2] = { 1, 7, 2, 7 };
    b[3] = { 0, 2, 0, 0 };

    Matrix4x4 exp; // Expected
    exp[0] = { -3, 5, 11, 7 };
    exp[1] = {  4, 2, 6, 1 };
    exp[2] = {  3, 5, 9, 12 };
    exp[3] = {  3, 2, 3, 0 };

    // Exercise
    Matrix4x4 result = a + b;

    // Verify
    REQUIRE(exp == result);

    return;
}

//! Tests that adding two matrices works as intended
TEST_CASE(__FILE__"/Operator_AddEquals", "[Matrix4x4]")
{
    // Setup
    Matrix4x4 a;
    a[0] = { -9, 5, 6, 7 };
    a[1] = { 1,  2, 5, 0 };
    a[2] = { 2, -2, 7, 5 };
    a[3] = { 3,  0, 3, 0 };

    Matrix4x4 b;
    b[0] = { 6, 0, 5, 0 };
    b[1] = { 3, 0, 1, 1 };
    b[2] = { 1, 7, 2, 7 };
    b[3] = { 0, 2, 0, 0 };

    Matrix4x4 exp; // Expected
    exp[0] = { -3, 5, 11, 7 };
    exp[1] = { 4, 2, 6, 1 };
    exp[2] = { 3, 5, 9, 12 };
    exp[3] = { 3, 2, 3, 0 };

    // Exercise
    a += b;

    // Verify
    REQUIRE(exp == a);

    return;
}

//! Tests that subtracting two matrices works as intended
TEST_CASE(__FILE__"/Operator_Sub", "[Matrix4x4]")
{
    // Setup
    Matrix4x4 a;
    a[0] = { -9, 5, 6, 7 };
    a[1] = { 1,  2, 5, 0 };
    a[2] = { 2, -2, 7, 5 };
    a[3] = { 3,  0, 3, 0 };

    Matrix4x4 b;
    b[0] = { -6, -0, -5, -0 };
    b[1] = { -3, -0, -1, -1 };
    b[2] = { -1, -7, -2, -7 };
    b[3] = { -0, -2, -0, -0 };

    Matrix4x4 exp; // Expected
    exp[0] = { -3, 5, 11, 7 };
    exp[1] = { 4, 2, 6, 1 };
    exp[2] = { 3, 5, 9, 12 };
    exp[3] = { 3, 2, 3, 0 };

    // Exercise
    Matrix4x4 result = a - b;

    // Verify
    REQUIRE(exp == result);

    return;
}

//! Tests that subtracting two matrices works as intended
TEST_CASE(__FILE__"/Operator_SubEuqals", "[Matrix4x4]")
{
    // Setup
    Matrix4x4 a;
    a[0] = { -9, 5, 6, 7 };
    a[1] = { 1,  2, 5, 0 };
    a[2] = { 2, -2, 7, 5 };
    a[3] = { 3,  0, 3, 0 };

    Matrix4x4 b;
    b[0] = { -6, -0, -5, -0 };
    b[1] = { -3, -0, -1, -1 };
    b[2] = { -1, -7, -2, -7 };
    b[3] = { -0, -2, -0, -0 };

    Matrix4x4 exp; // Expected
    exp[0] = { -3, 5, 11, 7 };
    exp[1] = { 4, 2, 6, 1 };
    exp[2] = { 3, 5, 9, 12 };
    exp[3] = { 3, 2, 3, 0 };

    // Exercise
    a -= b;

    // Verify
    REQUIRE(exp == a);

    return;
}

// Tests that the multiplication operator for a double parameter works
TEST_CASE(__FILE__"/Operator_MultiplyDouble", "[Matrix4x4]")
{
    // Setup
    Matrix4x4 a;
    a[0] = { -9, 5, 6, 7 };
    a[1] = {  1, 2, 5, 0 };
    a[2] = {  2,-2, 7, 5 };
    a[3] = {  3, 0, 3, 0 };

    double s = LARGE_RAND_DOUBLE;

    Matrix4x4 exp; // Expected
    exp[0] = { -9*s, 5*s, 6*s, 7*s };
    exp[1] = {  1*s, 2*s, 5*s, 0*s };
    exp[2] = {  2*s,-2*s, 7*s, 5*s };
    exp[3] = {  3*s, 0*s, 3*s, 0*s };

    // Exercise
    Matrix4x4 result = a * s;

    // Verify
    REQUIRE(exp.Similar(result));

    return;
}

// Tests that the multiplication operator for a double parameter works
TEST_CASE(__FILE__"/Operator_MultiplyEqualsDouble", "[Matrix4x4]")
{
    // Setup
    Matrix4x4 a;
    a[0] = { -9, 5, 6, 7 };
    a[1] = {  1, 2, 5, 0 };
    a[2] = {  2,-2, 7, 5 };
    a[3] = {  3, 0, 3, 0 };

    double s = LARGE_RAND_DOUBLE;

    Matrix4x4 exp; // Expected
    exp[0] = { -9*s, 5*s, 6*s, 7*s };
    exp[1] = {  1*s, 2*s, 5*s, 0*s };
    exp[2] = {  2*s,-2*s, 7*s, 5*s };
    exp[3] = {  3*s, 0*s, 3*s, 0*s };

    // Exercise
    a *= s;

    // Verify
    REQUIRE(exp.Similar(a));

    return;
}

// Tests that the division operator for a double parameter works
TEST_CASE(__FILE__"/Operator_DivideDouble", "[Matrix4x4]")
{
    // Setup
    Matrix4x4 a;
    a[0] = { -9, 5, 6, 7 };
    a[1] = {  1, 2, 5, 0 };
    a[2] = {  2,-2, 7, 5 };
    a[3] = {  3, 0, 3, 0 };

    double s = LARGE_RAND_DOUBLE;

    Matrix4x4 exp; // Expected
    exp[0] = { -9/s, 5/s, 6/s, 7/s };
    exp[1] = {  1/s, 2/s, 5/s, 0/s };
    exp[2] = {  2/s,-2/s, 7/s, 5/s };
    exp[3] = {  3/s, 0/s, 3/s, 0/s };

    // Exercise
    Matrix4x4 result = a / s;

    // Verify
    REQUIRE(exp.Similar(result));

    return;
}

// Tests that the division operator for a double parameter works
TEST_CASE(__FILE__"/Operator_DivideEqualsDouble", "[Matrix4x4]")
{
    // Setup
    Matrix4x4 a;
    a[0] = { -9, 5, 6, 7 };
    a[1] = {  1, 2, 5, 0 };
    a[2] = {  2,-2, 7, 5 };
    a[3] = {  3, 0, 3, 0 };

    double s = LARGE_RAND_DOUBLE;

    Matrix4x4 exp; // Expected
    exp[0] = { -9/s, 5/s, 6/s, 7/s };
    exp[1] = {  1/s, 2/s, 5/s, 0/s };
    exp[2] = {  2/s,-2/s, 7/s, 5/s };
    exp[3] = {  3/s, 0/s, 3/s, 0/s };

    // Exercise
    a /= s;

    // Verify
    REQUIRE(exp.Similar(a));

    return;
}

// Tests that matrix division (multiplication with inverse) works
TEST_CASE(__FILE__"/Operator_DivideMatrix", "[Matrix4x4]")
{
    // Setup
    Matrix4x4 a;
    a[0] = { 0.0503814, 0.3314391, 0.9421304, 33 };
    a[1] = { 0.4941404, 0.8115034, -0.3119095, 44 };
    a[2] = { -0.8679211, 0.4812591, -0.1228928 , 55 };
    a[3] = { 0, 0, 0, 1 };

    Matrix4x4 b;
    b[0] = { -0.3980391, -0.5301175, -0.7486925, 3 };
    b[1] = { 0.3352839, 0.6756021, -0.6566175, 4 };
    b[2] = { 0.8539026, -0.5123839, -0.0911762  , 5 };
    b[3] = { 0, 0, 0, 1 };

    Matrix4x4 expected = a * b.Inverse3x3();
    // Just to be sure, but should already be set
    expected.SetTranslationComponent(Vector3d(30, 40, 50));

    // Exercise
    Matrix4x4 actual = a / b;

    // Verify
    REQUIRE(expected.Similar(actual));

    return;
}

// Tests that matrix division (multiplication with inverse) works
TEST_CASE(__FILE__"/Operator_DivideEqualsMatrix", "[Matrix4x4]")
{
    // Setup
    Matrix4x4 a;
    a[0] = { 0.0503814, 0.3314391, 0.9421304, 33 };
    a[1] = { 0.4941404, 0.8115034, -0.3119095, 44 };
    a[2] = { -0.8679211, 0.4812591, -0.1228928 , 55 };
    a[3] = { 0, 0, 0, 1 };

    Matrix4x4 b;
    b[0] = { -0.3980391, -0.5301175, -0.7486925, 3 };
    b[1] = { 0.3352839, 0.6756021, -0.6566175, 4 };
    b[2] = { 0.8539026, -0.5123839, -0.0911762  , 5 };
    b[3] = { 0, 0, 0, 1 };

    Matrix4x4 expected = a * b.Inverse3x3();
    // Just to be sure, but should already be set
    expected.SetTranslationComponent(Vector3d(30, 40, 50));

    // Exercise
    a /= b;

    // Verify
    REQUIRE(expected.Similar(a));

    return;
}

// Tests that Math::Similar() works -> true
TEST_CASE(__FILE__"/Similar_True", "[Matrix4x4]")
{
    Matrix4x4 a;
    a[0] = { 1, 0, 0, 0 };
    a[1] = { 0, 1, 0, 0 };
    a[2] = { 0, 0, 1, 0 };
    a[3] = { 0, 0, 0, 1 };

    Matrix4x4 b;
    b[0] = { 1, -9e-20, 2e-8, 9e-19 };
    b[1] = { 12e-19, 1, -20e-15, -6.9e-29 };
    b[2] = { -69e-25, 13e-23, 1, 4.301e-15 };
    b[3] = { -23e-19, 23e-19, 25e-7, 1 };

    REQUIRE(a.Similar(b));
}

// Tests that Math::Similar() works -> false
TEST_CASE(__FILE__"/Similar_False", "[Matrix4x4]")
{
    Matrix4x4 a;
    a[0] = { 1, 0, 0, 0 };
    a[1] = { 0, 1, 0, 0 };
    a[2] = { 0, 0, 1, 0 };
    a[3] = { 0, 0, 0, 1 };

    Matrix4x4 b;
    b[0] = { 1, -9e-20, 2e-8, 9e-19 };
    b[1] = { 12e-19, 1, -20e-15, 0.05 }; // <--
    b[2] = { -69e-25, 13e-23, 1, 4.301e-15 };
    b[3] = { -23e-19, 23e-19, 25e-7, 1 };

    REQUIRE_FALSE(a.Similar(b));
}

// Tests if the equal operator (==) and not-equals operator (!=) work (equal: false)
TEST_CASE(__FILE__"/Operator_Equals_NotEquals_False", "[Matrix4x4]")
{
    Matrix4x4 a;
    a[0] = { 0x0, 0x1, 0x2, 0x3 };
    a[1] = { 0x4, 0x5, 0x6, 0x7 };
    a[2] = { 0x8, 0x9, 0xA, 0xB };
    a[3] = { 0xC, 0xD, 0xE, 0xF };

    Matrix4x4 b;
    b[3] = { 0xF ,0xD, 0xE, 0xC };
    b[2] = { 0xB ,0x9, 0xA, 0x8 };
    b[1] = { 0x7 ,0x5, 0x6, 0x4 };
    b[0] = { 0x3 ,0x1, 0x2, 0x0 };

    REQUIRE_FALSE(a == b);
    REQUIRE(a != b);
    return;
}

// Tests if the equal operator (==) and not-equals operator (!=) work (equal: true)
TEST_CASE(__FILE__"/Operator_Equals_False", "[Matrix4x4]")
{
    Matrix4x4 a;
    a[0] = { 0x0, 0x1, 0x2, 0x3 };
    a[1] = { 0x4, 0x5, 0x6, 0x7 };
    a[2] = { 0x8, 0x9, 0xA, 0xB };
    a[3] = { 0xC, 0xD, 0xE, 0xF };

    Matrix4x4 b;
    b[0] = { 0x0, 0x1, 0x2, 0x3 };
    b[1] = { 0x4, 0x5, 0x6, 0x7 };
    b[2] = { 0x8, 0x9, 0xA, 0xB };
    b[3] = { 0xC, 0xD, 0xE, 0xF };

    REQUIRE(a == b);
    REQUIRE_FALSE(a != b);
    return;
}

// Tests if the equal const operator (==) and not-equals operator (!=) work (equal: false)
TEST_CASE(__FILE__"/Operator_Equals_Const_NotEquals_False", "[Matrix4x4]")
{
    Matrix4x4 a;
    a[0] = { 0x0, 0x1, 0x2, 0x3 };
    a[1] = { 0x4, 0x5, 0x6, 0x7 };
    a[2] = { 0x8, 0x9, 0xA, 0xB };
    a[3] = { 0xC, 0xD, 0xE, 0xF };

    Matrix4x4 b;
    b[3] = { 0xF ,0xD, 0xE, 0xC };
    b[2] = { 0xB ,0x9, 0xA, 0x8 };
    b[1] = { 0x7 ,0x5, 0x6, 0x4 };
    b[0] = { 0x3 ,0x1, 0x2, 0x0 };

    const Matrix4x4 a_const = a;
    const Matrix4x4 b_const = b;

    REQUIRE_FALSE(a_const == b_const);
    REQUIRE(a_const != b_const);
    return;
}

// Tests if the equal const operator (==) and not-equals operator (!=) work (equal: true)
TEST_CASE(__FILE__"/Operator_Equals_Const_False", "[Matrix4x4]")
{
    Matrix4x4 a;
    a[0] = { 0x0, 0x1, 0x2, 0x3 };
    a[1] = { 0x4, 0x5, 0x6, 0x7 };
    a[2] = { 0x8, 0x9, 0xA, 0xB };
    a[3] = { 0xC, 0xD, 0xE, 0xF };

    Matrix4x4 b;
    b[0] = { 0x0, 0x1, 0x2, 0x3 };
    b[1] = { 0x4, 0x5, 0x6, 0x7 };
    b[2] = { 0x8, 0x9, 0xA, 0xB };
    b[3] = { 0xC, 0xD, 0xE, 0xF };

    const Matrix4x4 a_const = a;
    const Matrix4x4 b_const = b;

    REQUIRE(a_const == b_const);
    REQUIRE_FALSE(a_const != b_const);
    return;
}