/* Copyright (C) 2019 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "lib/self_test.h"
#include "lib/rand.h"

#include <iostream>
#include <random>
#include <chrono>
#include <boost/random/mersenne_twister.hpp>
#include <boost/random/uniform_real_distribution.hpp>

class TestSoundGroup : public CxxTest::TestSuite
{
public:
    void test_generation()
    {
        unsigned int samples = 1000000;
        float min = 0.0f;
        float max = 1000.0f;
        float value = 0.f;

        for (unsigned int i = 0; i < samples; ++i)
        {
            value = RandFloat(min, max);
            TS_ASSERT(value >= min && value <= max);
            m_BoostRng.seed(i);
            value = RandFloatBoost(min, max);
            TS_ASSERT(value >= min && value <= max);
            m_StlRng.seed(i);
            value = RandFloatStl(min, max);
            TS_ASSERT(value >= min && value <= max);
        }
    }

    void test_speed()
    {
        unsigned int samples = 10000000;
        float min = 0.0f;
        float max = 1.0f;
        float value = 0.f;

        std::chrono::high_resolution_clock::time_point begin = std::chrono::high_resolution_clock::now();
        for (unsigned int i = 0; i < samples; ++i)
        {
            value = RandFloat(min, max);
        }
        std::chrono::high_resolution_clock::time_point end = std::chrono::high_resolution_clock::now();
        TS_ASSERT(value >= min && value <= max);
        std::cout << std::endl;
        float defaultSeconds = (std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin).count() / 1000000000.f);
        std::cout << "RandFloat(float min, float max): " << defaultSeconds << " seconds" << std::endl;

        begin = std::chrono::high_resolution_clock::now();
        for (unsigned int i = 0; i < samples; ++i)
        {
            m_BoostRng.seed(i);
            value = RandFloatBoost(min, max);
        }
        end = std::chrono::high_resolution_clock::now();
        float boostSeconds = (std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin).count() / 1000000000.f);
        std::cout << "RandFloatBoost(float min, float max): " << boostSeconds << " seconds" << std::endl;
        TS_ASSERT(value >= min && value <= max);

        begin = std::chrono::high_resolution_clock::now();
        for (unsigned int i = 0; i < samples; ++i)
        {
            m_StlRng.seed(i);
            value = RandFloatStl(min, max);
        }

        end = std::chrono::high_resolution_clock::now();
        float stlSeconds = (std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin).count() / 1000000000.f);

        std::cout << "RandFloatStl(float min, float max): " << (std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin).count() / 1000000000.f) << " seconds" << std::endl;
        TS_ASSERT(value >= min && value <= max);
        TS_ASSERT(stlSeconds < boostSeconds && boostSeconds > defaultSeconds && stlSeconds > defaultSeconds);
    }

private:
    static boost::random::mt19937 m_BoostRng;
    static std::mt19937 m_StlRng;

    static float RandFloat(float min, float max)
    {
        return rand(static_cast<size_t>(min * 100.f), static_cast<size_t>(max * 100.f)) / 100.f;
    }

    static float RandFloatBoost(float min, float max)
    {
        return boost::random::uniform_real_distribution<float>(min, max)(m_BoostRng);
    }

    static float RandFloatStl(float min, float max)
    {
        return std::uniform_real_distribution<float>(min, max)(m_StlRng);
    }
};

boost::random::mt19937 TestSoundGroup::m_BoostRng;
std::mt19937 TestSoundGroup::m_StlRng;