/*]  Copyright (c) 2009-2010, Charles McGarvey  [**************************
**]  All rights reserved.
*
* vi:ts=4 sw=4 tw=75
*
* Distributable under the terms and conditions of the 2-clause BSD license;
* see the file COPYING for a complete text of the license.
*
**************************************************************************/

#ifndef _MOOF_TIMER_HH_
#define _MOOF_TIMER_HH_

/**
 * \file timer.hh
 * Functions for measuring time in a friendly unit.
 */

#include <map>

#include <boost/bind.hpp>
#include <boost/function.hpp>

#include <moof/math.hh>


namespace moof {


class timer
{
public:

	enum mode
	{
		invalid		= -1,
		normal		=  0,
		absolute	=  1,
		repeat		=  2
	};

	typedef boost::function<void(timer&,scalar)> function;


	timer() :
		mode_(invalid) {}

	timer(const function& function, scalar seconds, mode mode = normal)
	{
		init(function, seconds, mode);
	}

	~timer()
	{
		invalidate();
	}

	void init(const function& function, scalar seconds, mode mode = normal);

	bool is_valid() const;
	void invalidate();

	void fire();

	scalar seconds_remaining() const;
	bool is_expired() const;
	bool is_repeating() const;


	/**
	 * Get the number of seconds since a fixed, arbitrary point in the
	 * past.
	 * \return Seconds.
	 */
	static scalar ticks();


	/**
	 * Put the thread to sleep for a certain period of time.  If absolute
	 * is true, then it will sleep until seconds after the fixed time in
	 * the past.  If absolute is false, it will sleep for seconds starting
	 * now.  Unlike system sleep functions, this one automatically resumes
	 * sleep if sleep was interrupted by a signal.  Therefore, calling this
	 * function is guaranteed to sleep for the requested amount of time
	 * (and maybe longer).
	 * \param seconds Number of seconds.
	 * \param mode The timer mode.
	 */
	static void sleep(scalar seconds, mode mode = normal);


	static scalar next_expiration()
	{
		return gNextFire;
	}

	static void fire_expired_timers();
	static void fire_expired_timers(scalar t);


private:

	static unsigned new_identifier();
	static scalar find_next_expiration();

	function	function_;
	mode		mode_;
	scalar		absolute_;
	scalar		interval_;
	unsigned	id_;

	static scalar						gNextFire;
	static std::map<unsigned,timer*>	gTimers;
};


} // namespace moof

#endif // _MOOF_TIMER_HH_