/*!
 * 06_light_shading.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: 14/02/2024
 *
 */

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

#include <catch.hpp>

#include "raytracing.h"

using namespace Raytracer;

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

SCENARIO("The normal on a sphere at point a on the x axis", "[features/spheres.feature]")
{
    GIVEN("s <- sphere()")
    {
        Sphere s;
        WHEN("n <- normal_at(s, point(1,0,0))")
        {
            Tuple n = s.normal_at(Tuple::Point(1, 0, 0));
            THEN("n = vector(1,0,0)")
            {
                REQUIRE(n == Tuple::Vector(1, 0, 0));
            }
        }
    }
}

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

SCENARIO("The normal on a sphere at point a on the y axis", "[features/spheres.feature]")
{
    GIVEN("s <- sphere()")
    {
        Sphere s;
        WHEN("n <- normal_at(s, point(0,1,0))")
        {
            Tuple n = s.normal_at(Tuple::Point(0, 1, 0));
            THEN("n = vector(0,1,0)")
            {
                REQUIRE(n == Tuple::Vector(0, 1, 0));
            }
        }
    }
}

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

SCENARIO("The normal on a sphere at point a on the z axis", "[features/spheres.feature]")
{
    GIVEN("s <- sphere()")
    {
        Sphere s;
        WHEN("n <- normal_at(s, point(0,0,1))")
        {
            Tuple n = s.normal_at(Tuple::Point(0, 0, 1));
            THEN("n = vector(0,0,1)")
            {
                REQUIRE(n == Tuple::Vector(0, 0, 1));
            }
        }
    }
}

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

SCENARIO("The normal on a sphere at a nonaxial point", "[features/spheres.feature]")
{
    GIVEN("s <- sphere()")
    {
        Sphere s;
        WHEN("n <- normal_at(s, point(sqrt(3)/3,sqrt(3)/3,sqrt(3)/3))")
        {
            Tuple n = s.normal_at(Tuple::Point(sqrt(3) / 3, sqrt(3) / 3, sqrt(3) / 3));
            THEN("n = vector(sqrt(3)/3,sqrt(3)/3,sqrt(3)/3))")
            {
                REQUIRE(n == Tuple::Vector(sqrt(3) / 3, sqrt(3) / 3, sqrt(3) / 3));
            }
        }
    }
}

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

SCENARIO("The normal is a normalized vector", "[features/spheres.feature]")
{
    GIVEN("s <- sphere()")
    {
        Sphere s;
        WHEN("n <- normal_at(s, point(sqrt(3)/3,sqrt(3)/3,sqrt(3)/3))")
        {
            Tuple n = s.normal_at(Tuple::Point(sqrt(3) / 3, sqrt(3) / 3, sqrt(3) / 3));
            THEN("n = normalize(n)")
            {
                REQUIRE(n == n.normalize());
            }
        }
    }
}

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

SCENARIO("Computing the normal on a translated sphere", "[features/spheres.feature]")
{
    GIVEN("s <- sphere()")
    {
        Sphere s;
        AND_GIVEN("set_transform(s, translation(0,1,0))")
        {
            s.set_transform(Matrix::translation(0, 1, 0));
            WHEN("n <- normal_at(s,point(0,1.70711,-0.70711))")
            {
                Tuple n = s.normal_at(Tuple::Point(0, 1.70711, -0.70711));
                THEN("n = vector(0,0.70711, -0.70711)")
                {
                    REQUIRE(n == Tuple::Vector(0, 0.70711, -0.70711));
                }
            }
        }
    }
}

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

SCENARIO("Computing the normal on a transformed sphere", "[features/spheres.feature]")
{
    GIVEN("s <- sphere()")
    {
        Sphere s;
        AND_GIVEN("m <- scaling(1,0.5,1) * rotation_z(pi/5)")
        {
            Matrix m = Matrix::scaling(1, 0.5, 1) * Matrix::rotation_z(std::numbers::pi / 5);
            AND_GIVEN("set_transform(s, m)")
            {
                s.set_transform(m);
                WHEN("n <- normal_at(s,point(0,sqrt(2)/2,sqrt(2)/2))")
                {
                    Tuple n = s.normal_at(Tuple::Point(0, sqrt(2) / 2, -sqrt(2) / 2));
                    THEN("n = vector(0,97014, -0.24254)")
                    {
                        REQUIRE(n == Tuple::Vector(0, 0.97014, -0.24254));
                    }
                }
            }
        }
    }
}