#include "thread_pool.h"
#include <algorithm>
#include <thread>
#include <utility>

namespace threading {
ThreadPool::ThreadPool() {
	size_t const thread_count{ std::max(std::thread::hardware_concurrency() - 1, 1u) };
	this->threads.reserve(thread_count);
	for (size_t i{ 0 }; i < thread_count; ++i) {
		this->threads.emplace_back(std::bind(&ThreadPool::ThreadFn, this));
	}
}

ThreadPool::~ThreadPool() {
	{ std::scoped_lock lock{ this->lock };
		this->shutdown = true;
		this->threadNotifier.notify_all();
	}
	for (std::thread &thread : this->threads) {
		thread.join();
	}
}

size_t ThreadPool::GetThreadCount() {
	return this->threads.size();
}

void ThreadPool::ScheduleTask(TaskFunc fn) {
	std::scoped_lock lock{ this->lock };
	this->taskQueue.emplace(std::move(fn));
	this->threadNotifier.notify_one();
}

void ThreadPool::ThreadFn() {
	TaskFunc function;
	for(;;) {
		{ std::unique_lock<std::mutex> lock{ this->lock };
			while (!this->shutdown && this->taskQueue.empty()) {
				this->threadNotifier.wait(lock);
			}
			if (this->taskQueue.empty()) {
				return;
			}
			function = std::move(this->taskQueue.front());
			this->taskQueue.pop();
		}

		function.operator()();
	}
}

ThreadPool tasks{};
}