#pragma once

#include "tl/detail/prologue.h"
#include "tl/result.h"
#include <tl/deque.h>

#include <mutex>
#include <condition_variable>
#include <cassert>

namespace tl
{
//////////////////////////////////////////////////////////////////////////

template <typename T>
class blocking_queue
{
public:
	explicit blocking_queue(size_t max_size) noexcept;
	~blocking_queue() noexcept;

	void exit() noexcept; //stop all processing, returns Exited
	void finish() noexcept; //once empty or full, stops all processing, returns Finished

	enum class push_error_code
	{
		Full,
		Timeout,
		Finished,
		Exited,
	};

	using push_result = result<void, push_error_code>;

	push_result push(T const& t) noexcept;
	push_result try_push(T const& t) noexcept;
	push_result push_for(T const& t, chrono::system_clock::duration duration) noexcept;
	push_result push_until(T const& t, chrono::system_clock::time_point time_point) noexcept;

	push_result push(T&& t) noexcept;
	push_result try_push(T&& t) noexcept;
	push_result push_for(T&& t, chrono::system_clock::duration duration) noexcept;
	push_result push_until(T&& t, chrono::system_clock::time_point time_point) noexcept;

	enum class pop_error_code
	{
		Empty,
		Timeout,
		Exited,
		Finished,
	};

	using pop_result = result<T, pop_error_code>;

	pop_result pop() noexcept;
	pop_result try_pop() noexcept;
	pop_result pop_for(chrono::system_clock::duration duration) noexcept;
	pop_result pop_until(chrono::system_clock::time_point time_point) noexcept;

	template <typename Container>
	using pop_many_result = result<Container, pop_error_code>;

	template <typename Container>
	pop_many_result<Container> pop_many(size_t max) noexcept;
	template <typename Container>
	pop_many_result<Container> try_pop_many(size_t max) noexcept;
	template <typename Container>
	pop_many_result<Container> pop_many_for(size_t max, chrono::system_clock::duration duration) noexcept;
	template <typename Container>
	pop_many_result<Container> pop_many_until(size_t max, chrono::system_clock::time_point time_point) noexcept;

	using pop_many_emplace_result = result<void, pop_error_code>;

	template <typename Container>
	pop_many_emplace_result pop_many_emplace(Container& dst, size_t max) noexcept;
	template <typename Container>
	pop_many_emplace_result try_pop_many_emplace(Container& dst, size_t max) noexcept;
	template <typename Container>
	pop_many_emplace_result pop_many_emplace_for(Container& dst, size_t max, chrono::system_clock::duration duration) noexcept;
	template <typename Container>
	pop_many_emplace_result pop_many_emplace_until(Container& dst, size_t max, chrono::system_clock::time_point time_point) noexcept;

	bool empty() const noexcept;
	bool full() const noexcept;
	size_t size() const noexcept;
	size_t max_size() const noexcept;
	size_t capacity() const noexcept;

private:
	push_result _push(T&& t, bool block, chrono::system_clock::time_point* time_point) noexcept;
	pop_result _pop(bool block, chrono::system_clock::time_point* time_point) noexcept;

	template <typename Container>
	pop_many_result<Container> _pop_many_emplace(Container& dst, size_t max, bool block, chrono::system_clock::time_point* time_point) noexcept;

	mutable std::mutex m_mutex;
	std::condition_variable m_cv;
	deque<T> m_queue;
	size_t m_max_size = 10;
	bool m_exit = false;
	bool m_finish = false;
};

//////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////

template <class T>
blocking_queue<T>::blocking_queue(size_t max_size) noexcept
	: m_max_size(max_size)
{
	TL_ASSERT(m_max_size > 0);
}

template <class T>
blocking_queue<T>::~blocking_queue() noexcept
{
	exit();
}

template <class T>
void blocking_queue<T>::exit() noexcept
{
	{
		std::unique_lock<std::mutex> lg(m_mutex);
		m_exit = true;
	}
	m_cv.notify_all();
}

template <class T>
void blocking_queue<T>::finish() noexcept
{
	{
		std::unique_lock<std::mutex> lg(m_mutex);
		m_finish = true;
	}
	m_cv.notify_all();
}

template <class T>
bool blocking_queue<T>::empty() const noexcept
{
	std::unique_lock<std::mutex> lg(m_mutex);
	return m_queue.empty();
}

template <class T>
bool blocking_queue<T>::full() const noexcept
{
	std::unique_lock<std::mutex> lg(m_mutex);
	return m_queue.size() == m_max_size;
}

template <class T>
size_t blocking_queue<T>::size() const noexcept
{
	std::unique_lock<std::mutex> lg(m_mutex);
	return m_queue.size();
}

template <class T>
size_t blocking_queue<T>::max_size() const noexcept
{
	return capacity();
}

template <class T>
size_t blocking_queue<T>::capacity() const noexcept
{
	return m_max_size;
}

template <class T>
typename blocking_queue<T>::push_result blocking_queue<T>::push(T const& t) noexcept
{
	return _push(T(t), true, nullptr);
}

template <class T>
typename blocking_queue<T>::push_result blocking_queue<T>::try_push(T const& t) noexcept
{
	return _push(T(t), false, nullptr);
}

template <class T>
typename blocking_queue<T>::push_result blocking_queue<T>::push(T&& t) noexcept
{
	return _push(std::move(t), true, nullptr);
}

template <class T>
typename blocking_queue<T>::push_result blocking_queue<T>::try_push(T&& t) noexcept
{
	return _push(std::move(t), false, nullptr);
}

template <class T>
typename blocking_queue<T>::push_result blocking_queue<T>::push_for(T const& t, chrono::system_clock::duration duration) noexcept
{
	chrono::system_clock::time_point until = chrono::system_clock::now() + duration;
	return _push(T(t), true, &until);
}

template <class T>
typename blocking_queue<T>::push_result blocking_queue<T>::push_until(T const& t, chrono::system_clock::time_point time_point) noexcept
{
	return _push(T(t), true, &time_point);
}

template <class T>
typename blocking_queue<T>::push_result blocking_queue<T>::push_for(T&& t, chrono::system_clock::duration duration) noexcept
{
	chrono::system_clock::time_point until = chrono::system_clock::now() + duration;
	return _push(std::move(t), true, &until);
}

template <class T>
typename blocking_queue<T>::push_result blocking_queue<T>::push_until(T&& t, chrono::system_clock::time_point time_point) noexcept
{
	return _push(std::move(t), true, &time_point);
}

template <typename T>
typename blocking_queue<T>::pop_result blocking_queue<T>::pop() noexcept
{
	return _pop(true, nullptr);
}

template <typename T>
typename blocking_queue<T>::pop_result blocking_queue<T>::try_pop() noexcept
{
	return _pop(false, nullptr);
}

template <typename T>
typename blocking_queue<T>::pop_result blocking_queue<T>::pop_for(chrono::system_clock::duration duration) noexcept
{
	chrono::system_clock::time_point until = chrono::system_clock::now() + duration;
	return _pop(true, &until);
}

template <typename T>
typename blocking_queue<T>::pop_result blocking_queue<T>::pop_until(chrono::system_clock::time_point time_point) noexcept
{
	return _pop(true, &time_point);
}

template <typename T>
template <typename Container>
result<Container, typename blocking_queue<T>::pop_error_code> blocking_queue<T>::pop_many(size_t max) noexcept
{
	Container container;
	return _pop_many_emplace(container, max, true, nullptr);
}

template <typename T>
template <typename Container>
result<Container, typename blocking_queue<T>::pop_error_code> blocking_queue<T>::try_pop_many(size_t max) noexcept
{
	Container container;
	return _pop_many_emplace(container, max, false, nullptr);
}

template <typename T>
template <typename Container>
result<Container, typename blocking_queue<T>::pop_error_code> blocking_queue<T>::pop_many_for(size_t max, chrono::system_clock::duration duration) noexcept
{
	Container container;
	chrono::system_clock::time_point until = chrono::system_clock::now() + duration;
	return _pop_many_emplace(container, max, true, &until);
}

template <typename T>
template <typename Container>
result<Container, typename blocking_queue<T>::pop_error_code> blocking_queue<T>::pop_many_until(size_t max, chrono::system_clock::time_point time_point) noexcept
{
	Container container;
	return _pop_many_emplace(container, max, true, &time_point);
}

template <typename T>
template <typename Container>
typename blocking_queue<T>::pop_many_emplace_result blocking_queue<T>::pop_many_emplace(Container& dst, size_t max) noexcept
{
	pop_many_result<Container> result = _pop_many_emplace(dst, max, true, nullptr);
	return (result.has_value()) ? success() : pop_many_emplace_result(result.error().code());
}

template <typename T>
template <typename Container>
typename blocking_queue<T>::pop_many_emplace_result blocking_queue<T>::try_pop_many_emplace(Container& dst, size_t max) noexcept
{
	pop_many_result<Container> result = _pop_many_emplace(dst, max, false, nullptr);
	return (result.has_value()) ? success() : pop_many_emplace_result(result.error().code());
}

template <typename T>
template <typename Container>
typename blocking_queue<T>::pop_many_emplace_result blocking_queue<T>::pop_many_emplace_for(Container& dst, size_t max, chrono::system_clock::duration duration) noexcept
{
	chrono::system_clock::time_point until = chrono::system_clock::now() + duration;
	pop_many_result<Container> result = _pop_many_emplace(dst, max, true, &until);
	return (result.has_value()) ? success() : pop_many_emplace_result(result.error().code());
}

template <typename T>
template <typename Container>
typename blocking_queue<T>::pop_many_emplace_result blocking_queue<T>::pop_many_emplace_until(Container& dst, size_t max, chrono::system_clock::time_point time_point) noexcept
{
	pop_many_result<Container> result = _pop_many_emplace(dst, max, true, &time_point);
	return (result.has_value()) ? success() : pop_many_emplace_result(result.error().code());
}

//////////////////////////////////////////////////////////////////////////

template <class T>
typename blocking_queue<T>::push_result blocking_queue<T>::_push(T&& t, bool block, chrono::system_clock::time_point* time_point) noexcept
{
	bool pushed_one = false;
	bool timed_out = false;

	const auto system_tp = time_point ? std::chrono::system_clock::now() + std::chrono::nanoseconds(chrono::duration_cast<chrono::nanoseconds>(*time_point - chrono::system_clock::now()).count()) : std::chrono::system_clock::now();

	//send the current datagram
	{
		std::unique_lock<std::mutex> lg(m_mutex);
		if (block)
		{
			while ((m_queue.size() >= m_max_size) & (!m_exit) & (!timed_out))
			{
				if (m_finish)
					return push_result(push_error_code::Finished);

				if (time_point)
				{
					m_cv.wait_until(lg, system_tp);
					if (chrono::system_clock::now() >= *time_point)
						timed_out = true;
				}
				else
					m_cv.wait(lg);
			}

			if (m_exit)
				return push_result(push_error_code::Exited);
		}

		if (m_queue.size() < m_max_size)
		{
			pushed_one = true;
			m_queue.push_back(std::move(t));
		}
		else if (m_finish)
			return push_result(push_error_code::Finished);
	}

	if (pushed_one)
	{
		m_cv.notify_all();
		return success();
	}
	return timed_out ? push_result(push_error_code::Timeout) : push_result(push_error_code::Full);
}

//////////////////////////////////////////////////////////////////////////

template <typename T>
template <typename Container>
result<Container, typename blocking_queue<T>::pop_error_code> blocking_queue<T>::_pop_many_emplace(Container& dst, size_t max, bool block, chrono::system_clock::time_point* time_point) noexcept
{
	const auto system_tp = time_point ? std::chrono::system_clock::now() + std::chrono::nanoseconds(chrono::duration_cast<chrono::nanoseconds>(*time_point - chrono::system_clock::now()).count()) : std::chrono::system_clock::now();

	bool got_some = false;
	bool timed_out = false;
	{
		//wait for data
		std::unique_lock<std::mutex> lg(m_mutex);
		if (block)
		{
			while (m_queue.empty() & (!m_exit) & (!timed_out))
			{
				if (m_finish)
					return pop_many_result<Container>(pop_error_code::Finished);

				if (time_point)
				{
					m_cv.wait_until(lg, system_tp);
					if (chrono::system_clock::now() >= *time_point)
						timed_out = true;
				}
				else
					m_cv.wait(lg);
			}

			if (m_exit)
				return pop_many_result<Container>(pop_error_code::Exited);
		}

		if (m_queue.empty() && m_finish)
			return pop_many_result<Container>(pop_error_code::Finished);

		while (!m_queue.empty())
		{
			if (dst.size() >= max)
				break;

			got_some = true;
			dst.push_back(std::move(m_queue.front()));
			m_queue.pop_front();
		}
	}
	if (got_some)
	{
		m_cv.notify_all();
		return pop_many_result<Container>(std::move(dst));
	}
	return timed_out ? pop_many_result<Container>(pop_error_code::Timeout) : pop_many_result<Container>(pop_error_code::Empty);
}

//////////////////////////////////////////////////////////////////////////

template <typename T>
typename blocking_queue<T>::pop_result blocking_queue<T>::_pop(bool block, chrono::system_clock::time_point* time_point) noexcept
{
	const auto system_tp = time_point ? std::chrono::system_clock::now() + std::chrono::nanoseconds(chrono::duration_cast<chrono::nanoseconds>(*time_point - chrono::system_clock::now()).count()) : std::chrono::system_clock::now();

	optional<T> opt_dst;
	bool timed_out = false;
	{
		//wait for data
		std::unique_lock<std::mutex> lg(m_mutex);
		if (block)
		{
			while (m_queue.empty() & (!m_exit) & (!timed_out))
			{
				if (m_finish)
					return pop_result(pop_error_code::Finished);

				if (time_point)
				{
					m_cv.wait_until(lg, system_tp);
					if (chrono::system_clock::now() >= *time_point)
						timed_out = true;
				}
				else
					m_cv.wait(lg);
			}

			if (m_exit)
				return pop_result(pop_error_code::Exited);
		}

		if (!m_queue.empty())
		{
			opt_dst = std::move(m_queue.front());
			m_queue.pop_front();
		}
		else if (m_finish)
			return pop_result(pop_error_code::Finished);
	}

	if (opt_dst.has_value())
	{
		m_cv.notify_all();
		return std::move(opt_dst.value());
	}
	return timed_out ? pop_result(pop_error_code::Timeout) : pop_result(pop_error_code::Empty);
}
}