/*
 * elapsed-timer.h -- measure elapsed time
 *
 * Copyright (c) 2013-2016 David Demelier <markand@malikania.fr>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef _IRCCD_ELAPSED_TIMER_H_
#define _IRCCD_ELAPSED_TIMER_H_

/**
 * @file ElapsedTimer.h
 * @brief Measure elapsed time
 */

#include <chrono>

namespace irccd {

/**
 * @class ElapsedTimer
 * @brief Measure elapsed time
 *
 * This class provides an abstraction to measure elapsed time since the
 * construction of the object.
 *
 * It uses std::chrono::high_resolution_clock for more precision and uses
 * milliseconds only.
 */
class ElapsedTimer {
public:
	using TimePoint = std::chrono::time_point<std::chrono::high_resolution_clock>;

private:
	TimePoint m_last;
	bool m_paused{false};
	unsigned m_elapsed{0};

public:
	/**
	 * Construct the elapsed timer, start counting.
	 */
	ElapsedTimer() noexcept;

	/**
	 * Virtual destructor defaulted.
	 */
	virtual ~ElapsedTimer() = default;

	/**
	 * Put the timer on pause, the already elapsed time is stored.
	 */
	void pause() noexcept;

	/**
	 * Restart the timer, does not reset it.
	 */
	void restart() noexcept;

	/**
	 * Reset the timer to 0.
	 */
	void reset() noexcept;

	/**
	 * Get the number of elapsed milliseconds.
	 *
	 * @return the milliseconds
	 */
	unsigned elapsed() noexcept;
};

} // !irccd

#endif // !_IRCCD_ELAPSED_TIMER_H_