/*!
 * 05_rays.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("Creating and querying a ray", "[features/rays.feature]")
{
    GIVEN("origin <- point(1, 2, 3)")
    {
        Tuple origin = Tuple::Point(1, 2, 3);
        AND_GIVEN("direction <- vector(4, 5, 6)")
        {
            Tuple direction = Tuple::Vector(4, 5, 6);
            WHEN("r <- ray(origin, direction)")
            {
                Ray r(origin, direction);
                THEN("r.origin = origin")
                {
                    REQUIRE(r.origin() == origin);
                }
                AND_THEN("r.direction = direction")
                {
                    REQUIRE(r.direction() == direction);
                }
            }
        }
    }
}

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

SCENARIO("Computing a point from a distance", "[features/rays.feature]")
{
    GIVEN("r <- ray(point(2, 3, 4), vector(1, 0, 0))")
    {
        Ray r(Tuple::Point(2, 3, 4), Tuple::Vector(1, 0, 0));
        THEN("position(r,0) = point(2, 3, 4)")
        {
            REQUIRE(r.position(0) == Tuple::Point(2, 3, 4));
        }
        AND_THEN("position(r,1) == point(3, 3, 4)")
        {
            REQUIRE(r.position(1) == Tuple::Point(3, 3, 4));
        }
        AND_THEN("position(r,-1) = point(1, 3, 4)")
        {
            REQUIRE(r.position(-1) == Tuple::Point(1, 3, 4));
        }
        AND_THEN("position(r,2.5) == point(4.5, 3, 4)")
        {
            REQUIRE(r.position(2.5) == Tuple::Point(4.5, 3, 4));
        }
    }
}

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

SCENARIO("A ray intersects a sphere at two points", "[features/spheres.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("s <- sphere()")
        {
            Sphere s;
            WHEN("xs <- intersect(s,r)")
            {
                Intersections xs = s.intersect(r);
                THEN("xs.count = 2")
                {
                    REQUIRE(xs.count() == 2);
                }
                AND_THEN("xs[0] = 4.0")
                {
                    REQUIRE(xs[0].distance_t() == 4.0);
                }
                AND_THEN("xs[1 = 6.0")
                {
                    REQUIRE(xs[1].distance_t() == 6.0);
                }
            }
        }
    }
}

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

SCENARIO("A ray intersects a sphere at a tangent", "[features/spheres.feature]")
{
    Ray r(Tuple::Point(0, 1, -5), Tuple::Vector(0, 0, 1));
    Sphere s;
    Intersections xs = s.intersect(r);

    REQUIRE(xs.count() == 2);
    REQUIRE(xs[0].distance_t() == 5.0);
    REQUIRE(xs[1].distance_t() == 5.0);
}

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

SCENARIO("A ray misses a sphere", "[features/spheres.feature]")
{
    Ray r(Tuple::Point(0, 2, -5), Tuple::Vector(0, 0, 1));
    Sphere s;
    Intersections xs = s.intersect(r);

    REQUIRE(xs.count() == 0);
}

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

SCENARIO("A originates inside a sphere", "[features/spheres.feature]")
{
    Ray r(Tuple::Point(0, 0, 0), Tuple::Vector(0, 0, 1));
    Sphere s;
    Intersections xs = s.intersect(r);

    REQUIRE(xs.count() == 2);
    REQUIRE(xs[0].distance_t() == -1.0);
    REQUIRE(xs[1].distance_t() == 1.0);
}

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

SCENARIO("A sphere is behind a ray", "[features/spheres.feature]")
{
    Ray r(Tuple::Point(0, 0, 5), Tuple::Vector(0, 0, 1));
    Sphere s;
    Intersections xs = s.intersect(r);

    REQUIRE(xs.count() == 2);
    REQUIRE(xs[0].distance_t() == -6.0);
    REQUIRE(xs[1].distance_t() == -4.0);
}

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

SCENARIO("Test Sphere Object", "[features/spheres.feature]")
{
    Sphere s1;
    Sphere s2 = s1;
    Sphere s3;

    REQUIRE(s1 == s2);
    REQUIRE(s1 != s3);
}

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

SCENARIO("An intersection encapsulates t and object", "[features/intersections.feature]")
{
    Sphere s;
    Intersection i(3.5, s);

    REQUIRE(i.distance_t() == 3.5);
    REQUIRE(i.object() == s);
}

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

SCENARIO("Aggregating intersections", "[features/intersections.feature]")
{
    Sphere s;
    Intersection i1(1, s);
    Intersection i2(2, s);
    Intersections xs = Intersections({i1, i2});

    REQUIRE(xs.count() == 2);
    REQUIRE(xs[0].distance_t() == 1);
    REQUIRE(xs[1].distance_t() == 2);
}

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

SCENARIO("Intersect sets the object on the intersection", "[features/spheres.feature]")
{
    Ray r(Tuple::Point(0, 0, 5), Tuple::Vector(0, 0, 1));
    Sphere s;
    Intersections xs = s.intersect(r);

    REQUIRE(xs.count() == 2);
    REQUIRE(xs[0].object() == s);
    REQUIRE(xs[1].object() == s);
}

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

SCENARIO("The hit, when all intersections have positive t", "[features/intersections.feature]")
{
    Sphere s;
    Intersection i1(1, s);
    Intersection i2(2, s);
    Intersections xs = Intersections({i2, i1});

    Intersection i = xs.hit();

    REQUIRE(i == i1);
}

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

SCENARIO("The hit, when some intersections have negative t", "[features/intersections.feature]")
{
    Sphere s;
    Intersection i1(-1, s);
    Intersection i2(1, s);
    Intersections xs = Intersections({i2, i1});

    Intersection i = xs.hit();

    REQUIRE(i == i2);
}

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

SCENARIO("The hit, when all intersections have negative t", "[features/intersections.feature]")
{
    Sphere s;
    Intersection i1(-2, s);
    Intersection i2(-1, s);
    Intersections xs = Intersections({i1, i2});

    auto i = xs.hit();

    // REQUIRE(i.has_value());
}

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

SCENARIO("The hit is always the lowest nonnegative intersection", "[features/intersections.feature]")
{
    Sphere s;
    Intersection i1(5, s);
    Intersection i2(7, s);
    Intersection i3(-3, s);
    Intersection i4(2, s);
    Intersections xs = Intersections({i1, i2, i3, i4});

    Intersection i = xs.hit();

    REQUIRE(i == i4);
}

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

SCENARIO("Translating a ray", "[features/rays.feature]")
{
    Ray r(Tuple::Point(1, 2, 3), Tuple::Vector(0, 1, 0));
    Matrix m = Matrix::translation(3, 4, 5);
    Ray r2   = r.transform(m);

    REQUIRE(r2.origin() == Tuple::Point(4, 6, 8));
    REQUIRE(r2.direction() == Tuple::Vector(0, 1, 0));
}

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

SCENARIO("Scaling a ray", "[features/rays.feature]")
{
    Ray r(Tuple::Point(1, 2, 3), Tuple::Vector(0, 1, 0));
    Matrix m = Matrix::scaling(2, 3, 4);
    Ray r2   = r.transform(m);

    REQUIRE(r2.origin() == Tuple::Point(2, 6, 12));
    REQUIRE(r2.direction() == Tuple::Vector(0, 3, 0));
}

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

SCENARIO("A sphere's default transformation", "[features/spheres.feature]")
{
    GIVEN("s <- Sphere()")
    {
        Sphere s;
        THEN("s.transform = identity_matrix")
        {
            REQUIRE(s.transform() == Matrix::identity());
        }
    }
}

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

SCENARIO("Changing a sphere's transformation", "[features/spheres.feature]")
{
    Sphere s;
    Matrix t = Matrix::translation(2, 3, 4);
    s.set_transform(t);
    REQUIRE(s.transform() == t);
}

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

SCENARIO("Intersecting a scaled sphere with a ray", "[features/spheres.feature]")
{
    Ray r(Tuple::Point(0, 0, -5), Tuple::Vector(0, 0, 1));
    Sphere s;
    s.set_transform(Matrix::scaling(2, 2, 2));
    Intersections xs = s.intersect(r);

    REQUIRE(xs.count() == 2);
    REQUIRE(xs[0].distance_t() == 3);
    REQUIRE(xs[1].distance_t() == 7);
}

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

SCENARIO("Intersecting a translated sphere with a ray", "[features/spheres.feature]")
{
    Ray r(Tuple::Point(0, 0, -5), Tuple::Vector(0, 0, 1));
    Sphere s;
    s.set_transform(Matrix::translation(5, 0, 0));
    Intersections xs = s.intersect(r);

    REQUIRE(xs.count() == 0);
}