/*!
 * 07_making_scene.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 <cmath>

#include <catch2/catch_test_macros.hpp>

#include "raytracing.h"

using namespace Raytracer;

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

SCENARIO("Creating a world", "[features/world.feature]")
{
    GIVEN("w <- world()")
    {
        World w;
        THEN("w contains no objects")
        {
            REQUIRE(w.objects_count() == 0);
        }
        AND_THEN("w has no light source")
        {
            REQUIRE(w.has_light() == false);
        }
    }
}

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

SCENARIO("The default world", "[features/world.feature]")
{
    GIVEN("light <- point_light(point(-10, 10, -10), color(1, 1, 1))")
    {
        PointLight light = PointLight(Tuple::Point(-10, 10, -10), Color(1, 1, 1));
        AND_GIVEN("s1 <- sphere")
        // with:
        //  |  material.color    | (0.8, 1.0, 0.6) |
        //  |  material.diffuse  |  0.7            |
        //  |  material.specular |  0.2            |
        {
            Sphere s1;
            s1.material().set_color(Color(0.8, 1.0, 0.6));
            s1.material().set_diffuse(0.7);
            s1.material().set_specular(0.2);
            AND_GIVEN("s2 <- sphere")
            // with:
            //  |  transform    | scaling(0.5, 0.5, 0.5) |
            {
                Sphere s2;
                s2.set_transform(Matrix::scaling(0.5, 0.5, 0.5));
                WHEN("w <- default_world")
                {
                    World w = World::default_world();
                    THEN("w.light = light")
                    {
                        REQUIRE(w.light() == light);
                    }
                    AND_THEN("w contains s1")
                    {
                        REQUIRE(w.contains(s1) == true);
                    }
                    AND_THEN("w contains s2")
                    {
                        REQUIRE(w.contains(s2) == true);
                    }
                }
            }
        }
    }
}

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

SCENARIO("Intersect a world with a ray", "[features/world.feature]")
{
    GIVEN("w <- default_world()")
    {
        World w = World::default_world();
        AND_GIVEN("r <- ray(point(0, 0, -5), vector(0, 0, 1))")
        {
            Ray r(Tuple::Point(0, 0, -5), Tuple::Vector(0, 0, 1));
            WHEN("xs <- intersect_world(w,r)")
            {
                Intersections xs = w.intersect_world(r);
                THEN("xs.count = 4")
                {
                    REQUIRE(xs.count() == 4);
                }
                AND_THEN("xs[0].t = 4")
                {
                    REQUIRE(xs[0].distance_t() == 4);
                }
                AND_THEN("xs[1].t = 4.5")
                {
                    REQUIRE(xs[1].distance_t() == 4.5);
                }
                AND_THEN("xs[2].t = 5.5")
                {
                    REQUIRE(xs[2].distance_t() == 5.5);
                }
                AND_THEN("xs[3].t = 6")
                {
                    REQUIRE(xs[3].distance_t() == 6);
                }
            }
        }
    }
}

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

SCENARIO("Precompute the state of an intersection", "[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;
            AND_GIVEN("i <- intersection(4, shape)")
            {
                Intersection i(4, &shape);
                WHEN("comps <- prepare_computations(i,r)")
                {
                    IntersectionData comps = i.prepare_computations(r);
                    THEN("comps.t = i.t")
                    {
                        REQUIRE(comps.distance_t() == i.distance_t());
                    }
                    AND_THEN("comps.object = i.object")
                    {
                        REQUIRE(comps.object() == i.object());
                    }
                    AND_THEN("comps.point = point(0, 0, -1)")
                    {
                        REQUIRE(comps.point() == Tuple::Point(0, 0, -1));
                    }
                    AND_THEN("comps.eyev = vector(0, 0, -1)")
                    {
                        REQUIRE(comps.eyev() == Tuple::Vector(0, 0, -1));
                    }
                    AND_THEN("comps.normalv = vector(0, 0, -1)")
                    {
                        REQUIRE(comps.normalv() == Tuple::Vector(0, 0, -1));
                    }
                }
            }
        }
    }
}

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

SCENARIO("The hit, when an intersection occurs on the outside", "[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;
            AND_GIVEN("i <- intersection(4, shape)")
            {
                Intersection i(4, &shape);
                WHEN("comps <- prepare_computations(i,r)")
                {
                    IntersectionData comps = i.prepare_computations(r);
                    THEN("comps.inside = false")
                    {
                        REQUIRE(comps.is_inside() == false);
                    }
                }
            }
        }
    }
}

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

SCENARIO("The hit, when an intersection occurs on the inside", "[features/intersections.feature]")
{
    GIVEN("r <- ray(point(0, 0, 0), vector(0, 0, 1))")
    {
        Ray r(Tuple::Point(0, 0, 0), Tuple::Vector(0, 0, 1));
        AND_GIVEN("shape <- sphere()")
        {
            Sphere shape;
            AND_GIVEN("i <- intersection(1, shape)")
            {
                Intersection i(1, &shape);
                WHEN("comps <- prepare_computations(i,r)")
                {
                    IntersectionData comps = i.prepare_computations(r);
                    THEN("comps.point = point(0, 0, 1)")
                    {
                        REQUIRE(comps.point() == Tuple::Point(0, 0, 1));
                    }
                    AND_THEN("comps.eyev = vector(0, 0, -1)")
                    {
                        REQUIRE(comps.eyev() == Tuple::Vector(0, 0, -1));
                    }
                    AND_THEN("comps.inside = false")
                    {
                        REQUIRE(comps.is_inside() == true);
                    }
                    AND_THEN("comps.normalv = vector(0, 0, -1)")
                    {
                        REQUIRE(comps.normalv() == Tuple::Vector(0, 0, -1));
                    }
                }
            }
        }
    }
}

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

SCENARIO("Shading an intersection", "[features/world.feature]")
{
    GIVEN("w <- default_world()")
    {
        World w = World::default_world();
        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("shape <- first object of w")
            {
                Shape *shape = w.objects(0);
                AND_GIVEN("i <- intersection(4, shape)")
                {
                    Intersection i(4, shape);
                    WHEN("comps <- prepare_computations(i,r)")
                    {
                        IntersectionData comps = i.prepare_computations(r);
                        AND_WHEN("c <- shade_hit(w, comps)")
                        {
                            Color c = w.shade_hit(comps);
                            THEN("c = color(0.38066, 0.47583, 0.2855)")
                            {
                                REQUIRE(c == Color(0.38066, 0.47583, 0.2855));
                            }
                        }
                    }
                }
            }
        }
    }
}

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

SCENARIO("Shading an intersection from the inside", "[features/world.feature]")
{
    GIVEN("w <- default_world()")
    {
        World w = World::default_world();
        AND_GIVEN("w.light <- point_light(point(0, 0.25, 0))")
        {
            w.set_light(PointLight(Tuple::Point(0, 0.25, 0), Color(1, 1, 1)));
            AND_GIVEN("r <- ray(point(0, 0, 0), vector(0, 0, 1))")
            {
                Ray r(Tuple::Point(0, 0, 0), Tuple::Vector(0, 0, 1));
                AND_GIVEN("shape <- second object of w")
                {
                    Shape *shape = w.objects(1);
                    AND_GIVEN("i <- intersection(0.5, shape)")
                    {
                        Intersection i(0.5, shape);
                        WHEN("comps <- prepare_computations(i,r)")
                        {
                            IntersectionData comps = i.prepare_computations(r);
                            AND_WHEN("c <- shade_hit(w, comps)")
                            {
                                Color c = w.shade_hit(comps);
                                THEN("c = color(0.90498, 0.90498, 0.90498)")
                                {
                                    REQUIRE(c == Color(0.90498, 0.90498, 0.90498));
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

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

SCENARIO("The color when a ray misses", "[features/world.feature]")
{
    GIVEN("w <- default_world()")
    {
        World w = World::default_world();
        AND_GIVEN("r <- ray(point(0, 0, -5), vector(0, 1, 0))")
        {
            Ray r(Tuple::Point(0, 0, -5), Tuple::Vector(0, 1, 0));
            WHEN("c <- color_at(w, r)")
            {
                Color c = w.color_at(r);
                THEN("c = color(0, 0, 0)")
                {
                    REQUIRE(c == Color(0, 0, 0));
                }
            }
        }
    }
}

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

SCENARIO("The color when a ray hits", "[features/world.feature]")
{
    GIVEN("w <- default_world()")
    {
        World w = World::default_world();
        AND_GIVEN("r <- ray(point(0, 0, -5), vector(0, 0, 1))")
        {
            Ray r(Tuple::Point(0, 0, -5), Tuple::Vector(0, 0, 1));
            WHEN("c <- color_at(w, r)")
            {
                Color c = w.color_at(r);
                THEN("c = color(0.38066, 0.47583, 0.2855)")
                {
                    REQUIRE(c == Color(0.38066, 0.47583, 0.2855));
                }
            }
        }
    }
}

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

SCENARIO("The color with an intersection behind the ray", "[features/world.feature]")
{
    GIVEN("w <- default_world()")
    {
        World w = World::default_world();
        AND_GIVEN("outer <- the first object in w")
        {
            Shape *outer = w.objects(0);
            AND_GIVEN("outer.material.ambient <- 1")
            {
                outer->material().set_ambient(1);
                AND_GIVEN("inner <- the second object in w")
                {
                    Shape *inner = w.objects(1);
                    AND_GIVEN("inner.material.ambient <- 1")
                    {
                        inner->material().set_ambient(1);
                        AND_GIVEN("r <- ray(point(0, 0, 0.75), vector(0, 0, -1))")
                        {
                            Ray r(Tuple::Point(0, 0, 0.75), Tuple::Vector(0, 0, -1));
                            WHEN("c <- color_at(w, r)")
                            {
                                Color c = w.color_at(r);
                                THEN("c = inner.material.color")
                                {
                                    REQUIRE(c == inner->material().color());
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

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

SCENARIO("The transformation matrix for the default orientation", "[features/transformations.feature]")
{
    GIVEN("from <- point(0, 0, 0)")
    {
        Tuple from = Tuple::Point(0, 0, 0);
        AND_GIVEN("to <- point(0, 0, -1)")
        {
            Tuple to = Tuple::Point(0, 0, -1);
            AND_GIVEN("up <- vector(0, 1, 0)")
            {
                Tuple up = Tuple::Vector(0, 1, 0);
                WHEN("t <- view_transform(from, to, up)")
                {
                    Matrix t = Matrix::view_transform(from, to, up);
                    THEN("t = identify_matrix")
                    {
                        REQUIRE(t == Matrix::identity());
                    }
                }
            }
        }
    }
}

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

SCENARIO("A view transformation matrix looking in positive z direction", "[features/transformations.feature]")
{
    GIVEN("from <- point(0, 0, 0)")
    {
        Tuple from = Tuple::Point(0, 0, 0);
        AND_GIVEN("to <- point(0, 0, 1)")
        {
            Tuple to = Tuple::Point(0, 0, 1);
            AND_GIVEN("up <- vector(0, 1, 0)")
            {
                Tuple up = Tuple::Vector(0, 1, 0);
                WHEN("t <- view_transform(from, to, up)")
                {
                    Matrix t = Matrix::view_transform(from, to, up);
                    THEN("t = scaling(-1, 1, -1)")
                    {
                        REQUIRE(t == Matrix::scaling(-1, 1, -1));
                    }
                }
            }
        }
    }
}

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

SCENARIO("A view transformation moves the world", "[features/transformations.feature]")
{
    GIVEN("from <- point(0, 0, 8)")
    {
        Tuple from = Tuple::Point(0, 0, 8);
        AND_GIVEN("to <- point(0, 0, 0)")
        {
            Tuple to = Tuple::Point(0, 0, 0);
            AND_GIVEN("up <- vector(0, 1, 0)")
            {
                Tuple up = Tuple::Vector(0, 1, 0);
                WHEN("t <- view_transform(from, to, up)")
                {
                    Matrix t = Matrix::view_transform(from, to, up);
                    THEN("t = translation(0, 0, -8)")
                    {
                        REQUIRE(t == Matrix::translation(0, 0, -8));
                    }
                }
            }
        }
    }
}

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

SCENARIO("An arbitrary view transformation", "[features/transformations.feature]")
{
    GIVEN("from <- point(1, 3, 2)")
    {
        Tuple from = Tuple::Point(1, 3, 2);
        AND_GIVEN("to <- point(4, -2, 8)")
        {
            Tuple to = Tuple::Point(4, -2, 8);
            AND_GIVEN("up <- vector(1, 1, 0)")
            {
                Tuple up = Tuple::Vector(1, 1, 0);
                WHEN("t <- view_transform(from, to, up)")
                {
                    Matrix t = Matrix::view_transform(from, to, up);
                    THEN("t iq the following 4x4 matrix")
                    {
                        // | -0.50709 | 0.50709 |  0.67612 | -2.36643 |
                        // |  0.76772 | 0.60609 |  0.12122 | -2.82843 |
                        // | -0.35857 | 0.59761 | -0.71714 |  0.00000 |
                        // |  0.00000 | 0.00000 |  0.00000 |  1.00000 |
                        REQUIRE(t == Matrix({
                                         {-0.50709, 0.50709,  0.67612, -2.36643},
                                         { 0.76772, 0.60609,  0.12122, -2.82843},
                                         {-0.35857, 0.59761, -0.71714,  0.00000},
                                         { 0.00000, 0.00000,  0.00000,  1.00000}
                        }));
                    }
                }
            }
        }
    }
}

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

SCENARIO("Constructing a camera", "[features/camera.feature]")
{
    GIVEN("hsize <- 160")
    {
        uint16_t hsize = 160;
        AND_GIVEN("vsize <- 120")
        {
            uint16_t vsize = 120;
            AND_GIVEN("field_of_view <- pi / 2")
            {
                double field_of_view = std::numbers::pi / 2;
                WHEN("c <- camera(hsize, vsize,field_of_view)")
                {
                    Camera c(hsize, vsize, field_of_view);
                    THEN("c.hsize = 160")
                    {
                        REQUIRE(c.hsize() == 160);
                    }
                    AND_THEN("c.vsize = 120")
                    {
                        REQUIRE(c.vsize() == 120);
                    }
                    AND_THEN("c.field_of_view = pi / 2")
                    {
                        REQUIRE(c.field_of_view() == std::numbers::pi / 2);
                    }
                    AND_THEN("c.transform = identity_matrix")
                    {
                        REQUIRE(c.transform() == Matrix::identity());
                    }
                }
            }
        }
    }
}

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

SCENARIO("The pixel size for a horizontal canvas", "[features/camera.feature]")
{
    GIVEN("c <- camera(200, 125, pi/2)")
    {
        Camera c(200, 125, std::numbers::pi / 2);
        THEN("c.pixel_size = 0.01")
        {
            REQUIRE(c.pixel_size() == 0.01);
        }
    }
}

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

SCENARIO("The pixel size for a vertical canvas", "[features/camera.feature]")
{
    GIVEN("c <- camera(125, 200, pi/2)")
    {
        Camera c(125, 200, std::numbers::pi / 2);
        THEN("c.pixel_size = 0.01")
        {
            REQUIRE(c.pixel_size() == 0.01);
        }
    }
}

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

SCENARIO("Constructing a ray through the center of the canvas", "[features/camera.feature]")
{
    GIVEN("c <- camera(201, 101, pi/2)")
    {
        Camera c(201, 101, std::numbers::pi / 2);
        WHEN("r <- ray_for_pixel(c, 100, 50)")
        {
            Ray r = c.ray_for_pixel(100, 50);
            THEN("r.origin = point(0, 0, 0)")
            {
                REQUIRE(r.origin() == Tuple::Point(0, 0, 0));
            }
        }
    }
}

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

SCENARIO("Constructing a ray through a corner of the canvas", "[features/camera.feature]")
{
    GIVEN("c <- camera(201, 101, pi/2)")
    {
        Camera c(201, 101, std::numbers::pi / 2);
        WHEN("r <- ray_for_pixel(c, 0, 0)")
        {
            Ray r = c.ray_for_pixel(0, 0);
            THEN("r.origin = point(0, 0, 0)")
            {
                REQUIRE(r.origin() == Tuple::Point(0, 0, 0));
            }
            AND_THEN("r.direction = vector(0.66519, 0.33259, -0.66851)")
            {
                REQUIRE(r.direction() == Tuple::Vector(0.66519, 0.33259, -0.66851));
            }
        }
    }
}

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

SCENARIO("Constructing a ray when the camera is transformed", "[features/camera.feature]")
{
    GIVEN("c <- camera(201, 101, pi/2)")
    {
        Camera c(201, 101, std::numbers::pi / 2);
        WHEN("c.transform <- rotation_y(pi/4) * translation(0, -2, 5)")
        {
            c.set_transform(Matrix::rotation_y(std::numbers::pi / 4) * Matrix::translation(0, -2, 5));
            AND_WHEN("r <- ray_for_pixel(c, 100, 50)")
            {
                Ray r = c.ray_for_pixel(100, 50);
                THEN("r.origin = point(0, 2, -5)")
                {
                    REQUIRE(r.origin() == Tuple::Point(0, 2, -5));
                }
                AND_THEN("r.direction = vector(sqrt(2) / 2, 0, -sqrt(2) / 2)")
                {
                    REQUIRE(r.direction() == Tuple::Vector(std::sqrt(2) / 2, 0, -std::sqrt(2) / 2));
                }
            }
        }
    }
}

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

SCENARIO("Rendering a world with the camera", "[features/camera.feature]")
{
    GIVEN("w <- default_world()")
    {
        World w = World::default_world();
        AND_GIVEN("c <- camera(11, 11, pi/2)")
        {
            Camera c(11, 11, std::numbers::pi / 2);
            AND_GIVEN("from <- point(0, 0, -5)")
            {
                Tuple from = Tuple::Point(0, 0, -5);
                AND_GIVEN("to <- point(0, 0, 0)")
                {
                    Tuple to = Tuple::Point(0, 0, 0);
                    AND_GIVEN("up <- vector(0, 1, 0)")
                    {
                        Tuple up = Tuple::Vector(0, 1, 0);
                        AND_GIVEN("c.transform <- view_transform(from, to, up)")
                        {
                            c.set_transform(Matrix::view_transform(from, to, up));
                            WHEN("image <- c.render(w)")
                            {
                                Canvas image = c.render(w);
                                THEN("pixel_at(image, 5, 5) = color(0.38066, 0.47583, 0.2855)")
                                {
                                    REQUIRE(image.pixel_at(5, 5) == Color(0.38066, 0.47583, 0.2855));
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}