/*!
 * 04_transformations.cpp
 *
 * Copyright (c) 2015-2024, NADAL Jean-Baptiste. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301 USA
 *
 * @Author:  NADAL Jean-Baptiste
 * @Date: 05/02/2024
 *
 */

/*---------------------------------------------------------------------------*/

#include <catch.hpp>

#include "raytracing.h"

using namespace Raytracer;

/* ------------------------------------------------------------------------- */

SCENARIO("Multiplying by a translation matrix", "[features/transformations.feature]")
{
    GIVEN("transform <- translation(5, -3, 2)")
    {
        Matrix transform = Matrix::translation(5, -3, 2);
        AND_GIVEN("p <- point(-3, 4, 5)")
        {
            Tuple p = Tuple::Point(-3, 4, 5);
            THEN("transform * p = point(2, 1, 7)")
            {
                REQUIRE(transform * p == Tuple::Point(2, 1, 7));
            }
        }
    }
}

/* ------------------------------------------------------------------------- */

SCENARIO("Multiplying by the inverse of a translation matrix", "[features/transformations.feature]")
{
    GIVEN("transform <- translation(5, -3, 2)")
    {
        Matrix transform = Matrix::translation(5, -3, 2);
        AND_GIVEN("inv <- inverse(transform)")
        {
            Matrix inv = transform.inverse();
            AND_GIVEN("p <- point(-3, 4, 5)")
            {
                Tuple p = Tuple::Point(-3, 4, 5);
                THEN("inv * p = point(-8, 7, 3)")
                {
                    REQUIRE(inv * p == Tuple::Point(-8, 7, 3));
                }
            }
        }
    }
}

/* ------------------------------------------------------------------------- */

SCENARIO("Translation does not affect vectors", "[features/transformations.feature]")
{
    GIVEN("transform <- translation(5, -3, 2)")
    {
        Matrix transform = Matrix::translation(5, -3, 2);
        AND_GIVEN("v <- vector(-3, 4, 5)")
        {
            Tuple v = Tuple::Vector(-3, 4, 5);
            THEN("transform * v = v")
            {
                REQUIRE(transform * v == v);
            }
        }
    }
}

/* ------------------------------------------------------------------------- */

SCENARIO("A scaling matrix applied to a point", "[features/transformations.feature]")
{
    GIVEN("transform <- scaling(2, 3, 4)")
    {
        Matrix transform = Matrix::scaling(2, 3, 4);
        AND_GIVEN("p <- point(-4, 6, 8)")
        {
            Tuple p = Tuple::Point(-4, 6, 8);
            THEN("transform * p = point(-8, 18, 32)")
            {
                REQUIRE(transform * p == Tuple::Point(-8, 18, 32));
            }
        }
    }
}

/* ------------------------------------------------------------------------- */

SCENARIO("A scaling matrix applied to a vector", "[features/transformations.feature]")
{
    GIVEN("transform <- scaling(2, 3, 4)")
    {
        Matrix transform = Matrix::scaling(2, 3, 4);
        AND_GIVEN("v <- vector(-4, 6, 8)")
        {
            Tuple v = Tuple::Vector(-4, 6, 8);
            THEN("transform * p = vector(-8, 18, 32)")
            {
                REQUIRE(transform * v == Tuple::Vector(-8, 18, 32));
            }
        }
    }
}

/* ------------------------------------------------------------------------- */

SCENARIO("Multiplying by the inverse of a scaling matrix", "[features/transformations.feature]")
{
    GIVEN("transform <- scaling(2, 3, 4)")
    {
        Matrix transform = Matrix::scaling(2, 3, 4);
        AND_GIVEN("inv <- inverse(transform)")
        {
            Matrix inv = transform.inverse();
            AND_GIVEN("v <- vector(-4, 6, 8)")
            {
                Tuple v = Tuple::Vector(-4, 6, 8);
                THEN("inv * v = vector(-2, 2, 2)")
                {
                    REQUIRE(inv * v == Tuple::Vector(-2, 2, 2));
                }
            }
        }
    }
}

/* ------------------------------------------------------------------------- */

SCENARIO("Reflection is scaling by a negative value", "[features/transformations.feature]")
{
    GIVEN("transform <- scaling(-1, 1, 1)")
    {
        Matrix transform = Matrix::scaling(-1, 1, 1);
        AND_GIVEN("p <- point(2, 3, 4)")
        {
            Tuple p = Tuple::Point(2, 3, 4);
            THEN("transform * p = point(-2, 3, 4)")
            {
                REQUIRE(transform * p == Tuple::Point(-2, 3, 4));
            }
        }
    }
}

/* ------------------------------------------------------------------------- */

SCENARIO("Rotating a point around the x axis", "[features/transformations.feature]")
{
    GIVEN("p <- point(0, 1, 0)")
    {
        Tuple p = Tuple::Point(0, 1, 0);
        AND_GIVEN("half_quarter <- rotation_x(pi/4)")
        {
            Matrix half_quarter = Matrix::rotation_x(std::numbers::pi / 4);
            AND_GIVEN("full_quarter <- rotation_x(pi/2)")
            {
                Matrix full_quarter = Matrix::rotation_x(std::numbers::pi / 2);
                THEN("half_quarter * p = point(0, sqrt(2) / 2, sqrt(2) / 2)")
                {
                    REQUIRE(half_quarter * p == Tuple::Point(0, sqrt(2) / 2, sqrt(2) / 2));
                }
                AND_THEN("full_quarter * p == point(0, 0, 1)")
                {
                    REQUIRE(full_quarter * p == Tuple::Point(0, 0, 1));
                }
            }
        }
    }
}

/* ------------------------------------------------------------------------- */

SCENARIO("The inverse of an x-rotation rotates in the opposite direction", "[features/transformations.feature]")
{
    GIVEN("p <- point(0, 1, 0)")
    {
        Tuple p = Tuple::Point(0, 1, 0);
        AND_GIVEN("half_quarter <- rotation_x(pi/4)")
        {
            Matrix half_quarter = Matrix::rotation_x(std::numbers::pi / 4);
            AND_GIVEN("inv <- inverse(half_quarter)")
            {
                Matrix inv = half_quarter.inverse();
                THEN("inv * p = point(0, sqrt(2) / 2, -sqrt(2) / 2)")
                {
                    REQUIRE(inv * p == Tuple::Point(0, sqrt(2) / 2, -sqrt(2) / 2));
                }
            }
        }
    }
}

/* ------------------------------------------------------------------------- */

SCENARIO("Rotating a point around the y axis", "[features/transformations.feature]")
{
    GIVEN("p <- point(0, 1, 0)")
    {
        Tuple p = Tuple::Point(0, 0, 1);
        AND_GIVEN("half_quarter <- rotation_y(pi/4)")
        {
            Matrix half_quarter = Matrix::rotation_y(std::numbers::pi / 4);
            AND_GIVEN("full_quarter <- rotation_y(pi/2)")
            {
                Matrix full_quarter = Matrix::rotation_y(std::numbers::pi / 2);
                THEN("half_quarter * p = point(sqrt(2) / 2, 0, sqrt(2) / 2)")
                {
                    REQUIRE(half_quarter * p == Tuple::Point(sqrt(2) / 2, 0, sqrt(2) / 2));
                }
                AND_THEN("full_quarter * p = point(1, 0, 0)")
                {
                    REQUIRE(full_quarter * p == Tuple::Point(1, 0, 0));
                }
            }
        }
    }
}

/* ------------------------------------------------------------------------- */

SCENARIO("Rotating a point around the z axis", "[features/transformations.feature]")
{
    GIVEN("p <- point(0, 1, 0)")
    {
        Tuple p = Tuple::Point(0, 1, 0);
        AND_GIVEN("full_quarter <- rotation_z(pi/4)")
        {
            Matrix half_quarter = Matrix::rotation_z(std::numbers::pi / 4);
            AND_GIVEN("full_quarter <- rotation_z(pi/2)")
            {
                Matrix full_quarter = Matrix::rotation_z(std::numbers::pi / 2);

                Tuple z = half_quarter * p;
                THEN("half_quarter * p = point(-sqrt(2) / 2, sqrt(2) / 2, 0)")
                {
                    REQUIRE(half_quarter * p == Tuple::Point(-sqrt(2) / 2, sqrt(2) / 2, 0));
                }
                AND_THEN("full_quarter * p = point(-1, 0, 0)")
                {
                    REQUIRE(full_quarter * p == Tuple::Point(-1, 0, 0));
                }
            }
        }
    }
}

/* ------------------------------------------------------------------------- */

SCENARIO("A shearing transformation moves x in proportion to y", "[features/transformations.feature]")
{
    GIVEN("transform <- shearing(1, 0, 0, 0, 0, 0)")
    {
        Matrix transform = Matrix::shearing(1, 0, 0, 0, 0, 0);
        AND_GIVEN("p <- point(2, 3, 4)")
        {
            Tuple p = Tuple::Point(2, 3, 4);
            THEN("transform * p == point(5, 3, 4)")
            {
                REQUIRE(transform * p == Tuple::Point(5, 3, 4));
            }
        }
    }
}

/* ------------------------------------------------------------------------- */

SCENARIO("A shearing transformation moves y in proportion to x", "[features/transformations.feature]")
{
    GIVEN("transform <- shearing(0, 0, 1, 0, 0, 0)")
    {
        Matrix transform = Matrix::shearing(0, 0, 1, 0, 0, 0);
        AND_GIVEN("p <- point(2, 3, 4)")
        {
            Tuple p = Tuple::Point(2, 3, 4);
            THEN("transform * p == point(2, 5, 4)")
            {
                REQUIRE(transform * p == Tuple::Point(2, 5, 4));
            }
        }
    }
}

/* ------------------------------------------------------------------------- */

SCENARIO("A shearing transformation moves y in proportion to z", "[features/transformations.feature]")
{
    GIVEN("transform <- shearing(0, 0, 0, 1, 0, 0)")
    {
        Matrix transform = Matrix::shearing(0, 0, 0, 1, 0, 0);
        AND_GIVEN("p <- point(2, 3, 4)")
        {
            Tuple p = Tuple::Point(2, 3, 4);
            THEN("transform * p == point(2, 7, 4)")
            {
                REQUIRE(transform * p == Tuple::Point(2, 7, 4));
            }
        }
    }
}

/* ------------------------------------------------------------------------- */

SCENARIO("A shearing transformation moves z in proportion to x", "[features/transformations.feature]")
{
    GIVEN("transform <- shearing(0, 0, 0, 0, 1, 0)")
    {
        Matrix transform = Matrix::shearing(0, 0, 0, 0, 1, 0);
        AND_GIVEN("p <- point(2, 3, 4)")
        {
            Tuple p = Tuple::Point(2, 3, 4);
            THEN("transform * p == point(2, 3, 6)")
            {
                REQUIRE(transform * p == Tuple::Point(2, 3, 6));
            }
        }
    }
}

/* ------------------------------------------------------------------------- */

SCENARIO("A shearing transformation moves z in proportion to y", "[features/transformations.feature]")
{
    GIVEN("transform <- shearing(0, 0, 0, 0, 0, 1)")
    {
        Matrix transform = Matrix::shearing(0, 0, 0, 0, 0, 1);
        AND_GIVEN("p <- point(2, 3, 4)")
        {
            Tuple p = Tuple::Point(2, 3, 4);
            THEN("transform * p == point(2, 3, 7)")
            {
                REQUIRE(transform * p == Tuple::Point(2, 3, 7));
            }
        }
    }
}

/* ------------------------------------------------------------------------- */

SCENARIO("Individual transformations are applied in sequence", "[features/transformations.feature]")
{
    GIVEN("p  <- point(1, 0, 1)")
    {
        Tuple p = Tuple::Point(1, 0, 1);
        AND_GIVEN("A <- rotation_x(pi/2)")
        {
            Matrix A = Matrix::rotation_x(std::numbers::pi / 2);
            AND_GIVEN("B <- scaling(5, 5, 5)")
            {
                Matrix B = Matrix::scaling(5, 5, 5);
                AND_GIVEN("C <- translation(10, 5, 7))")
                {
                    Matrix C = Matrix::translation(10, 5, 7);

                    // Apply rotation first.
                    WHEN("p2 <- A * p")
                    {
                        Tuple p2 = A * p;
                        THEN("p2 = point(1, -1, 0)")
                        {
                            REQUIRE(p2 == Tuple::Point(1, -1, 0));
                        }

                        // Then Apply scaling
                        WHEN("p3 <- B * p2")
                        {
                            Tuple p3 = B * p2;
                            THEN("p3 = point(5, -5, 0)")
                            {
                                REQUIRE(p3 == Tuple::Point(5, -5, 0));
                            }
                            // Then Apply translation
                            WHEN("p4 = C * p3")

                            {
                                Tuple p4 = C * p3;
                                THEN("p4 = point(15, 0, 7)")
                                {
                                    REQUIRE(p4 == Tuple::Point(15, 0, 7));
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

/* ------------------------------------------------------------------------- */

SCENARIO("Chained transformation must be applied in revert order", "[features/transformations.feature]")
{
    GIVEN("p  <- point(1, 0, 1)")
    {
        Tuple p = Tuple::Point(1, 0, 1);
        AND_GIVEN("A <- rotation_x(pi/2)")
        {
            Matrix A = Matrix::rotation_x(std::numbers::pi / 2);
            AND_GIVEN("B <- scaling(5, 5, 5)")
            {
                Matrix B = Matrix::scaling(5, 5, 5);
                AND_GIVEN("C <- translation(10, 5, 7))")
                {
                    Matrix C = Matrix::translation(10, 5, 7);
                    WHEN("t <- C * B * A")
                    {
                        Matrix T = C * B * A;
                        THEN("T * p == point(15, 0, 7)")
                        {
                            REQUIRE(T * p == Tuple::Point(15, 0, 7));
                        }
                    }
                }
            }
        }
    }
}