/*
 *  DoRayMe - a quick and dirty Raytracer
 *  Light unit tests
 *
 *  Created by Manoël Trapier
 *  Copyright (c) 2020 986-Studio.
 *
 */
#include <light.h>
#include <math.h>
#include <math_helper.h>
#include <colour.h>
#include <tuple.h>
#include <gtest/gtest.h>
#include <world.h>
#include <worldbuilder.h>

TEST(LightTest, A_point_lighthas_a_position_and_intensity)
{
    Colour intensity = Colour(1, 1, 1);
    Point position = Point(0, 0, 0);

    Light light = Light(POINT_LIGHT, position, intensity);

    ASSERT_EQ(light.position, position);
    ASSERT_EQ(light.intensity, intensity);
}

TEST(LightTest, Point_lights_evaluate_the_lights_intensity_at_a_given_point)
{
    World w = DefaultWorld();
    Light *light = w.getLight(0);

    Tuple testList[] = {
            Point(0, 1.0001, 0),
            Point(-1.0001, 0, 0),
            Point(0, 0, -1.0001),
            Point(0, 0, 1.0001),
            Point(1.0001, 0, 0),
            Point(0, -1.0001, 0),
            Point(0, 0, 0),
    };

    double testResult[] = {
            1.0,
            1.0,
            1.0,
            0.0,
            0.0,
            0.0,
            0.0,
    };

    int testCount = sizeof(testList)/sizeof((testList)[0]);
    int i;

    for(i = 0; i < testCount; i++)
    {
        ASSERT_TRUE(double_equal(light->intensityAt(w, testList[i]), testResult[i]));
    }
}

TEST(LightTest, Creating_an_area_light)
{
    Tuple corner = Point(0, 0, 0);
    Tuple v1 = Vector(2, 0, 0);
    Tuple v2 = Vector(0, 0, 1);

    Light light = Light(AREA_LIGHT, corner, v1, 4, v2, 2, Colour(1, 1, 1));

    /* Position is used to store the corner in area lights */
    ASSERT_EQ(light.corner, corner);
    ASSERT_EQ(light.uVec, Vector(0.5, 0, 0));
    ASSERT_EQ(light.uSteps, 4);
    ASSERT_EQ(light.vVec, Vector(0, 0, 0.5));
    ASSERT_EQ(light.vSteps, 2);
    ASSERT_EQ(light.samples, 8);
    ASSERT_EQ(light.position, Point(1, 0, 0.5));
}

TEST(LightTest, Finding_a_single_point_on_an_area_light)
{
    Tuple corner = Point(0, 0, 0);
    Tuple v1 = Vector(2, 0, 0);
    Tuple v2 = Vector(0, 0, 1);

    Light light = Light(AREA_LIGHT, corner, v1, 4, v2, 2, Colour(1, 1, 1));

    uint32_t testList[][2] = {
            {0, 0},
            {1, 0},
            {0, 1},
            {2, 0},
            {3, 1},
    };

    Point testResults[] {
        Point(0.25, 0, 0.25),
        Point(0.75, 0, 0.25),
        Point(0.25, 0, 0.75),
        Point(1.25, 0, 0.25),
        Point(1.75, 0, 0.75),
    };

    int testCount = sizeof(testList)/sizeof((testList)[0]);
    int i;

    for(i = 0; i < testCount; i++)
    {
        Tuple tp = light.pointOnLight(testList[i][0], testList[i][1]);
        ASSERT_EQ(tp, testResults[i]);
    }

}

TEST(LightTest, The_area_light_intensity_function)
{
    World w = DefaultWorld();
    Tuple corner = Point(-0.5, -0.5, -5);
    Tuple v1 = Vector(1, 0, 0);
    Tuple v2 = Vector(0, 1, 0);

    Light light = Light(AREA_LIGHT, corner, v1, 2, v2, 2, Colour(1, 1, 1));

    Point testList[] = {
            Point(0, 0, 2),
            Point(1, -1, 2),
            Point(1.5, 0, 2),
            Point(1.25, 1.25, 3),
            Point(0, 0, -2),
    };

    double testResults[] {
        0.0,
        0.25,
        0.5,
        0.75,
        1,
    };

    int testCount = sizeof(testList)/sizeof((testList)[0]);
    int i;

    for(i = 0; i < testCount; i++)
    {
        double intensity = light.intensityAt(w, testList[i]);
        ASSERT_TRUE(double_equal(intensity, testResults[i]));
    }
}

TEST(LightTest, Finding_a_single_point_on_a_jittered_area_light)
{
    Tuple corner = Point(0, 0, 0);
    Tuple v1 = Vector(2, 0, 0);
    Tuple v2 = Vector(0, 0, 1);

    Light light = Light(AREA_LIGHT, corner, v1, 4, v2, 2, Colour(1, 1, 1), true);

    double seqList[] = { 0.3, 0.7 };
    light.jitterBy = Sequence(seqList, 2);

    uint32_t testList[][2] = {
            {0, 0},
            {1, 0},
            {0, 1},
            {2, 0},
            {3, 1},
    };

    Point testResults[] {
            Point(0.15, 0, 0.35),
            Point(0.65, 0, 0.35),
            Point(0.15, 0, 0.85),
            Point(1.15, 0, 0.35),
            Point(1.65, 0, 0.85),
    };

    int testCount = sizeof(testList)/sizeof((testList)[0]);
    int i;

    for(i = 0; i < testCount; i++)
    {
        Tuple tp = light.pointOnLight(testList[i][0], testList[i][1]);
        ASSERT_EQ(tp, testResults[i]);
    }
}

TEST(LightTest, The_area_light_with_jittered_samples)
{
    World w = DefaultWorld();
    Tuple corner = Point(-0.5, -0.5, -5);
    Tuple v1 = Vector(1, 0, 0);
    Tuple v2 = Vector(0, 1, 0);

    Light light = Light(AREA_LIGHT, corner, v1, 2, v2, 2, Colour(1, 1, 1), true);
    double seqList[] = { 0.7, 0.3, 0.9, 0.1, 0.5 };
    light.jitterBy = Sequence(seqList, 5);

    Point testList[] = {
            Point(0, 0, 2),
            Point(1, -1, 2),
            Point(1.5, 0, 2),
            Point(1.25, 1.25, 3),
            Point(0, 0, -2),
    };

    double testResults[] {
            0.0,
            0.25, /* Chapter say 0.5 but it's not what I get here ?! */
            0.75,
            0.75,
            1,
    };

    int testCount = sizeof(testList)/sizeof((testList)[0]);
    int i;

    for(i = 0; i < testCount; i++)
    {
        double intensity = light.intensityAt(w, testList[i]);
        EXPECT_TRUE(double_equal(intensity, testResults[i]));
    }
}