// =====================================================================================================================
//  fennec, a free and open source game engine
//  Copyright © 2025  Medusa Slockbower
//
//  This program 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 3 of the License, or
//  (at your option) any later version.
//
//  This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.
// =====================================================================================================================

///
/// \file test_threading.h
/// \brief
///
///
/// \details
/// \author Medusa Slockbower
///
/// \copyright Copyright © 2025 Medusa Slockbower ([GPLv3](https://www.gnu.org/licenses/gpl-3.0.en.html))
///
///


#ifndef FENNEC_TEST_THREADING_H
#define FENNEC_TEST_THREADING_H

#include <chrono>
#include <fennec/threading/atomic.h>
#include <fennec/threading/lock_guard.h>
#include <fennec/threading/mpscq.h>
#include <fennec/threading/mutex.h>
#include <fennec/threading/thread.h>

namespace fennec::test
{

inline void fennec_test_threading_test_atomic(atomic<size_t>* test_atomic, size_t N = 1000) {
	for (size_t i = 0; i < N; ++i) {
		++*test_atomic;
	}
}

template<size_t ThreadsV>
inline void fennec_test_threading_run_test_atomic(array<thread, ThreadsV>& threads, size_t N = 1000) {
	atomic<size_t> test = 0;
	for (thread& t : threads) {
		t = thread(fennec_test_threading_test_atomic, &test, N);
	}
	for (thread& t : threads) {
		t.join();
	}
	fennec_test_run(test.load(), N * ThreadsV);
}



inline void fennec_test_threading_test_mutex(size_t* var, mutex* m, size_t N = 1000) {
	for (size_t i = 0; i < N; ++i) {
		lock_guard guard(*m);
		++*var;
	}
}

template<size_t ThreadsV>
inline void fennec_test_threading_run_test_mutex(array<thread, ThreadsV>& threads, size_t N = 1000) {
	mutex m;
	size_t test = 0;
	for (thread& t : threads) {
		t = thread(fennec_test_threading_test_mutex, &test, &m, N);
	}
	for (thread& t : threads) {
		t.join();
	}
	fennec_test_run(test, N * ThreadsV);
}



inline void fennec_test_threading_test_mpscq_producer(mpscq<size_t>* queue, size_t N = 1000) {
	for (size_t i = 0; i < N; ++i) {
		queue->emplace(1);
	}
}

inline void fennec_test_threading_test_mpscq_consumer(mpscq<size_t>* queue, atomic<size_t>* res, atomic<bool>* done) {
	while (not done->load() or not queue->is_empty()) {
		unique_ptr<size_t> ptr = queue->pop();
		if (ptr) {
			*res += *ptr;
		}
	}
}

template<size_t ThreadsV>
inline void fennec_test_threading_run_test_mpscq(array<thread, ThreadsV>& threads, size_t N = 1000) {
	mpscq<size_t> queue(N * ThreadsV);
	for (size_t i = 1; i < ThreadsV; ++i) {
		threads[i] = thread(fennec_test_threading_test_mpscq_producer, &queue, N);
	}
	atomic<size_t> test;
	atomic<bool> done;
	threads[0] = thread(fennec_test_threading_test_mpscq_consumer, &queue, &test, &done);
	for (size_t i = 1; i < ThreadsV; ++i) {
		threads[i].join();
	}
	done.store(true);
	threads[0].join();
	fennec_test_run(test.load(), N * (ThreadsV - 1));
}

template<typename ReturnT, typename...ParamsT, typename...ArgsT>
inline double fennec_test_threading_timed(ReturnT (func)(ParamsT...), ArgsT&&...args) {
	auto start = std::chrono::high_resolution_clock::now();
	func(fennec::forward<ArgsT>(args)...);
	return std::chrono::duration<double>(std::chrono::high_resolution_clock::now() - start).count();
}


inline void fennec_test_threading() {

	static constexpr size_t N = 100000, threads = 8;

	array<thread, threads> arr;

	std::cout << fennec_test_threading_timed(fennec_test_threading_run_test_atomic<threads>, arr, N) << "s\n";
	std::cout << fennec_test_threading_timed(fennec_test_threading_run_test_mutex<threads>, arr, N) << "s\n";
	std::cout << fennec_test_threading_timed(fennec_test_threading_run_test_mpscq<threads>, arr, N) << "s\n";
}

}

#endif // FENNEC_TEST_THREADING_H