/**
 * \file
 * \author Karsten Rink
 * \date   2014-08-29
 *
 * \copyright
 * Copyright (c) 2012-2021, OpenGeoSys Community (http://www.opengeosys.org)
 *            Distributed under a Modified BSD License.
 *              See accompanying file LICENSE.txt or
 *              http://www.opengeosys.org/project/license
 *
 *
 */

#include <memory>
#include <random>

#include "gtest/gtest.h"

#include "GeoLib/MinimalBoundingSphere.h"
#include "MathLib/Point3d.h"

std::vector<MathLib::Point3d*>* getRandomSpherePoints(
    MathLib::Point3d const& center, double const radius, std::size_t n_points)
{
    Eigen::Vector3d const c({center[0], center[1], center[2]});
    auto* pnts = new std::vector<MathLib::Point3d*>;
    pnts->reserve(n_points);

    std::random_device rd;
    std::mt19937 gen(rd());
    std::uniform_real_distribution<> dis(-1, 1);

    for (std::size_t k(0); k < n_points; ++k)
    {
        Eigen::Vector3d const random_point({dis(gen), dis(gen), dis(gen)});
        Eigen::Vector3d const t = c + radius * random_point.normalized();
        pnts->push_back(new MathLib::Point3d({t[0], t[1], t[2]}));
    }
    return pnts;
}

TEST(GeoLib, TestBoundingSphere)
{
    std::vector<MathLib::Point3d*> pnts;
    pnts.push_back(new MathLib::Point3d(std::array<double,3>({{0,  0   , 0}})));
    pnts.push_back(new MathLib::Point3d(std::array<double,3>({{2,  0   , 0}})));
    pnts.push_back(new MathLib::Point3d(std::array<double,3>({{1,  0.1 , 0}})));
    pnts.push_back(new MathLib::Point3d(std::array<double,3>({{1, -0.1 , 0}})));

    {
    /**
     * Four points located like this:
     *
     *              *
     *     *                  *
     *              *
     *
     * Tests if a smaller number of points than available is used if the resulting sphere is smaller.
     * Expected result is C=(1,0,0), r=1
     */
    GeoLib::MinimalBoundingSphere s(pnts);
    MathLib::Point3d center = s.getCenter();
    ASSERT_NEAR(1.0, center[0], std::numeric_limits<double>::epsilon());
    ASSERT_NEAR(0.0, center[1], std::numeric_limits<double>::epsilon());
    ASSERT_NEAR(0.0, center[2], std::numeric_limits<double>::epsilon());
    ASSERT_NEAR(1.0, s.getRadius(), std::numeric_limits<double>::epsilon());
    }

    {
    /**
     * Four points located like this:
     *
     *          *
     *    *           *
     *
     *
     *          *
     *
     * The smallest sphere has a diameter that is larger than the distance between any two points.
     * Expected result is C=(1,0.0246,-0.3446), r=1.058
     */
    (*pnts[2])[2] -= 1.4;
    GeoLib::MinimalBoundingSphere s(pnts);
    MathLib::Point3d center = s.getCenter();
    ASSERT_NEAR(1.0, center[0], 0.0001);
    ASSERT_NEAR(0.0246, center[1], 0.0001);
    ASSERT_NEAR(-0.3446, center[2], 0.0001);
    ASSERT_NEAR(1.0580, s.getRadius(), 0.0001);
    }

    (*pnts[0])[0] = 0.0;
    (*pnts[0])[1] = 0.0;
    (*pnts[0])[2] = 0.0;
    (*pnts[1])[0] = 1.0;
    (*pnts[1])[1] = 0.0;
    (*pnts[1])[2] = 0.0;
    (*pnts[2])[0] = 1.0;
    (*pnts[2])[1] = 1.0;
    (*pnts[2])[2] = 0.0;
    (*pnts[3])[0] = 0.0;
    (*pnts[3])[1] = 1.0;
    (*pnts[3])[2] = 0.0;
    pnts.push_back(new MathLib::Point3d(std::array<double,3>({{0, 0, 1}})));
    pnts.push_back(new MathLib::Point3d(std::array<double,3>({{1, 0, 1}})));
    pnts.push_back(new MathLib::Point3d(std::array<double,3>({{1, 1, 1}})));
    pnts.push_back(new MathLib::Point3d(std::array<double,3>({{0, 1, 0.9}})));

    {
    /**
     * A "cube" where one node is pushed slightly towards the centre (and should be ignored).
     * Expected result is C=(0.5,0.5,0.5), r=0.866
     */
    GeoLib::MinimalBoundingSphere s(pnts);
    MathLib::Point3d center = s.getCenter();
    ASSERT_NEAR(0.5, center[0], std::numeric_limits<double>::epsilon());
    ASSERT_NEAR(0.5, center[1], std::numeric_limits<double>::epsilon());
    ASSERT_NEAR(0.5, center[2], std::numeric_limits<double>::epsilon());
    ASSERT_NEAR(0.8660, s.getRadius(), 0.0001);
    }

    /**
     * A "cube" where one node is pulled away from the centre (making the resulting sphere larger).
     * Expected result is C=(0.5,0.5,0.6), r=0.9273
     */
    (*pnts[7])[2] += 0.3;
    GeoLib::MinimalBoundingSphere s(pnts);
    {
    MathLib::Point3d center = s.getCenter();
    ASSERT_NEAR(0.5, center[0], std::numeric_limits<double>::epsilon());
    ASSERT_NEAR(0.5, center[1], std::numeric_limits<double>::epsilon());
    ASSERT_NEAR(0.6, center[2], std::numeric_limits<double>::epsilon());
    ASSERT_NEAR(0.9273, s.getRadius(), 0.0001);
    }

    /// Calculates the bounding sphere of points on a bounding sphere
    auto sphere_points = std::unique_ptr<std::vector<MathLib::Point3d*>>(
        getRandomSpherePoints(s.getCenter(), s.getRadius(), 1000));
    GeoLib::MinimalBoundingSphere t(*sphere_points);
    for (auto p : *sphere_points)
    {
        delete p;
    }
    MathLib::Point3d center = t.getCenter();
    ASSERT_NEAR(0.5, center[0], 1e2 * std::numeric_limits<double>::epsilon());
    ASSERT_NEAR(0.5, center[1], 1e2 * std::numeric_limits<double>::epsilon());
    ASSERT_NEAR(0.6, center[2], 1e2 * std::numeric_limits<double>::epsilon());
    ASSERT_NEAR(0.9273, t.getRadius(), 0.0001);

    std::for_each(pnts.begin(), pnts.end(),
        std::default_delete<MathLib::Point3d>());
}