/**
 *  @file
 *  @author     2016 Stefan Radomski (stefan.radomski@cs.tu-darmstadt.de)
 *  @copyright  Simplified BSD
 *
 *  @cond
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the FreeBSD license as published by the FreeBSD
 *  project.
 *
 *  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.
 *
 *  You should have received a copy of the FreeBSD license along with this
 *  program. If not, see <http://www.opensource.org/licenses/bsd-license>.
 *  @endcond
 */

#include "BasicEventQueue.h"
#include <event2/util.h>                // for evutil_socket_t
#include <event2/thread.h>
#include <assert.h>

#include "uscxml/interpreter/Logging.h"

namespace uscxml {

BasicEventQueue::BasicEventQueue() {
}
BasicEventQueue::~BasicEventQueue() {
}

Event BasicEventQueue::dequeue(size_t blockMs) {
	std::lock_guard<std::recursive_mutex> lock(_mutex);

	if (blockMs == std::numeric_limits<size_t>::max()) {
		// handle "forever" explicitly, see comments below
		while (_queue.empty()) {
			_cond.wait(_mutex);
		}

	} else if (blockMs > 0) {
		using namespace std::chrono;

		// TODO: do read http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2661.htm
		system_clock::time_point now = system_clock::now();
		system_clock::time_point endTime = now + milliseconds(blockMs);

		// now + milliseconds(blockMs) may not have fitted into a duration type - limit to maximum duration
		if (blockMs > (size_t)(system_clock::duration::max().count() - duration_cast<milliseconds>(now.time_since_epoch()).count())) {
			/**
			 * Some compilers do not like to wait_until system_clock::time_point::max():
			 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58931
			 * http://stackoverflow.com/questions/39041450/stdcondition-variable-wait-until-surprising-behaviour
			 *
			 * See also:
			 * https://github.com/tklab-tud/uscxml/issues/101
			 * https://github.com/tklab-tud/uscxml/issues/132
			 */
			endTime = system_clock::time_point::max();
		}

		// block for given milliseconds or until queue is non-empty
		while (endTime > std::chrono::system_clock::now() && _queue.empty()) {
			_cond.wait_until(_mutex, endTime);
		}
	}

	if (_queue.size() > 0) {
		Event event = _queue.front();
		_queue.pop_front();
//        LOG(USCXML_ERROR) << event.name;
		return event;
	}
	return Event();

}

void BasicEventQueue::enqueue(const Event& event) {
	std::lock_guard<std::recursive_mutex> lock(_mutex);
	_queue.push_back(event);
	_cond.notify_all();
}

void BasicEventQueue::reset() {
	std::lock_guard<std::recursive_mutex> lock(_mutex);
	_queue.clear();
}

Data BasicEventQueue::serialize() {
	std::lock_guard<std::recursive_mutex> lock(_mutex);
	Data serialized;

	for (auto event : _queue) {
		serialized["BasicEventQueue"].array.push_back(event);
	}
	return serialized;
}

void BasicEventQueue::deserialize(const Data& data) {
	if (data.hasKey("BasicEventQueue")) {
		std::lock_guard<std::recursive_mutex> lock(_mutex);
		for (auto event : data["BasicEventQueue"].array) {
			_queue.push_back(Event::fromData(event));
		}
	}
}

std::shared_ptr<EventQueueImpl> BasicEventQueue::create() {
	return std::shared_ptr<EventQueueImpl>(new BasicEventQueue());
}

}