/*!
 * 08_shadows.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: 26/02/2024
 *
 */

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

#include <catch.hpp>

#include "raytracing.h"

using namespace Raytracer;

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

SCENARIO("Lightning with the surface in shadow", "[features/materials.feature]")
{
    Tuple position = Tuple::Point(0, 0, 0);
    Material m;

    GIVEN("eyev <- vector(0, 0, -1)")
    {
        Tuple eyev = Tuple::Vector(0, 0, -1);
        AND_GIVEN("normalv <- vector(0, 0, -1)")
        {
            Tuple normalv = Tuple::Vector(0, 0, -1);
            AND_GIVEN("light <- point_light(point(0, 0, -10), color(1, 1, 1))")
            {
                PointLight light = PointLight(Tuple::Point(0, 0, -10), Color(1, 1, 1));
                AND_GIVEN("in_shadow <- true")
                {
                    bool in_shadow = true;
                    WHEN("result <- lighting(m, light, position, eyev, normalv, in_shadow)")
                    {
                        Color result = m.lighting(light, position, eyev, normalv, in_shadow);
                        THEN("result = color(0.1, 0.1, 0.1)")
                        {
                            REQUIRE(result == Color(0.1, 0.1, 0.1));
                        }
                    }
                }
            }
        }
    }
}

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

SCENARIO("There is no shadow when noting is collinear with p&l", "[features/world.feature]")
{
    GIVEN("w <- default_world()")
    {
        World w = World::default_world();
        AND_GIVEN("p <- point(0, 10, 0)")
        {
            Tuple p = Tuple::Point(0, 10, 0);
            THEN("is_shadowed(w, p) is false")
            {
                REQUIRE(w.is_shadowed(p) == false);
            }
        }
    }
}

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

SCENARIO("There shadow when an object is between the p&l", "[features/world.feature]")
{
    GIVEN("w <- default_world()")
    {
        World w = World::default_world();
        AND_GIVEN("p <- point(10, -10, 10)")
        {
            Tuple p = Tuple::Point(10, -10, 10);
            THEN("is_shadowed(w, p) is true")
            {
                REQUIRE(w.is_shadowed(p) == true);
            }
        }
    }
}

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

SCENARIO("There is no shadow when an object is behind the p&l", "[features/world.feature]")
{
    GIVEN("w <- default_world()")
    {
        World w = World::default_world();
        AND_GIVEN("p <- point(-20, 20, -20)")
        {
            Tuple p = Tuple::Point(-20, 20, -20);
            THEN("is_shadowed(w, p) is false")
            {
                REQUIRE(w.is_shadowed(p) == false);
            }
        }
    }
}

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

SCENARIO("There is no shadow when an object is behind the point", "[features/world.feature]")
{
    GIVEN("w <- default_world()")
    {
        World w = World::default_world();
        AND_GIVEN("p <- point(-2, 2, -2)")
        {
            Tuple p = Tuple::Point(-2, 2, -2);
            THEN("is_shadowed(w, p) is false")
            {
                REQUIRE(w.is_shadowed(p) == false);
            }
        }
    }
}

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

SCENARIO("shade_hit() is given an intersection in the shadow", "[features/world.feature]")
{
    GIVEN("w <- world()")
    {
        World w;
        AND_GIVEN("w.light <- point_light(point(0, 0, -10), color(1, 1, 1))")
        {
            w.set_light(PointLight(Tuple::Point(0, 0, -10), Color(1, 1, 1)));
            AND_GIVEN("s1 <- sphere()")
            {
                Sphere *s1 = new Sphere;
                AND_GIVEN("s1 is added to w")
                {
                    w.add_object(s1);
                    AND_GIVEN("s2 <- sphere() with transform(translation(0, 0, 10))")
                    {
                        Sphere *s2 = new Sphere;
                        s2->set_transform(Matrix::translation(0, 0, 10));
                        AND_GIVEN("s2 is added to w")
                        {
                            w.add_object(s2);
                            AND_GIVEN("r <- ray(point(0, 0, 5), vector(0, 0, 1))")
                            {
                                Ray r(Tuple::Point(0, 0, 5), Tuple::Vector(0, 0, 1));
                                AND_GIVEN("i <- intersection(4, s2)")
                                {
                                    Intersection i(4, *s2);
                                    WHEN("comps <- prepare_computatons(i,r)")
                                    {
                                        IntersectionData comps = i.prepare_computations(r);
                                        AND_WHEN("c <- shade_hit(w, comps)")
                                        {
                                            Color c = w.shade_hit(comps);
                                            THEN("c = color (0.1, 0.1, 0.1)")
                                            {
                                                REQUIRE(c == Color(0.1, 0.1, 0.1));
                                            }
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

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

SCENARIO("The hit should offset the point", "[features/intersections.feature]")
{
    GIVEN("r <- ray(point(0, 0, -5), vector(0, 0, 1))")
    {
        Ray r(Tuple::Point(0, 0, -5), Tuple::Vector(0, 0, 1));
        AND_GIVEN("shape <- sphere()")
        {
            Sphere shape;
            shape.set_transform(Matrix::translation(0, 0, 1));
            AND_GIVEN("i <- intersection(5, shape)")
            {
                Intersection i(5, shape);
                WHEN("comps <- prepare_computatons(i,r)")
                {
                    IntersectionData comps = i.prepare_computations(r);
                    THEN("comps.over_point.z < -EPSILON/2")
                    {
                        REQUIRE(comps.over_point().z() < -kEpsilon / 2);
                    }
                    AND_THEN("comps.point.z < comps.over_point.z")
                    {
                        REQUIRE(comps.point().z() > comps.over_point().z());
                    }
                }
            }
        }
    }
}