/*
    This file is part of CubicVR.

    CubicVR is free software; you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation; either version 2.1 of the License, or
    (at your option) any later version.

    CubicVR 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.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with CubicVR; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    
    
    Source (c) 2003 by Charles J. Cliffe unless otherwise specified
    To contact me, e-mail or MSN to cj@cubicproductions.com or by ICQ#7188044
    http://www.cubicproductions.com
*/

#ifndef TIMER_H
#define TIMER_H

#ifndef _WIN32
#include <sys/time.h>
#endif

/// Timer Class, high resolution timer
/**
 * Class provides high resolution timing and useful time control functions
 */
 
class Timer
{
private:
		
	unsigned long time_elapsed;
	unsigned long system_milliseconds;
	unsigned long start_time;
	unsigned long end_time;
	unsigned long last_update;
	unsigned long num_updates;
	unsigned long paused_time;
	unsigned long offset;

#ifndef _WIN32
	struct timeval time_val;
	struct timezone time_zone;                                                                                            
#endif


	bool paused_state;
	bool lock_state;
	float lock_rate;

public:

	/// Constructor
	Timer();

	/// Start the timer
	/**
	 *  Resets the timer to 0 and begins timing
	 */
	void start(void);
	
	/// Stop the timer
	/**
	 *  Stops the timer and records the end time
	 */
	void stop(void);
	
	
	/// Locks the timer to a specified framerate (for recording / benchmarking purposes typically)
	/**
	 *  Locks the timer to a specified framerate (for recording / benchmarking purposes typically)
	 */
	void lockFramerate(float f_rate);

	
	/// Unlock any framerate lock that's been applied
	/**
	 *  Unlock any framerate lock that's been applied
	 */
	void unlock();

	
	/// Check locked state
	/**
	 *  Check locked state
	 */
	bool locked();
	
	
	/// Reset the timer counter
	/**
	 *	Resetting the timer will reset the current time to 0
	 */
	void reset(void);

	
	/// Timer update
	/**
	 *	Calling the update command will bring the timer value up to date, this is meant
	 *	to be called at the begining of the frame to establish the time index which is being drawn.
	 */
	void update(void);

	
	/// Get the total time elapsed since the timer start, not counting paused time
	/**
	 *	Returns the total time elapsed in since the timer start() to the last update() but 
	 *	does not count the time elapsed while the timer is paused().
	 *  \return Total time elapsed since the timer start() to the last update() excluding time paused() in milliseconds
	 */
	unsigned long getMilliseconds(void);
	/// Alias of getMilliseconds() which returns time in seconds
	/**
	 *  \return Total time elapsed since the timer start() to the last update() excluding time paused() in seconds
	 */
	double getSeconds(void);

	
	/// Get the total time elapsed since the timer start
	/**
	 *	Returns the total time elapsed in since the timer start() to the last update()
	 *  this includes any time accumulated during updates while paused()
	 *  \return Total time elapsed since the timer start() to the last update() including time paused() in milliseconds
	 */
	unsigned long totalMilliseconds(void);
	/// Alias of totalMilliseconds() which returns time in seconds
	/**
	 *  \return Total time elapsed since the timer start() to the last update() including time paused() in seconds
	 */
	double totalSeconds(void);

	 
	/// Set the amount of time elapsed
	/**
	 *	Force the timer duration to a specific value, useful for rolling forward or back in a system
	 *	based upon the timer.
	 *  \param milliseconds_in Time to set timer to in milliseconds
	 */
	void setMilliseconds(unsigned long milliseconds_in);
	/// alias of setMilliseconds() which accepts time in seconds
	/**
	 *  \param seconds_in Time to set timer to in seconds
	 */
	void setSeconds(double seconds_in);

	
	/// Get the amount of times the update() command has been called
	/**
	 * 	By using the number of times the update() command has been called you can easily determine
	 *  an average frame rate. Also useful for merely determining how many frames have been drawn.
	 *  \return Number of times update() has been called
	 */
	unsigned long getNumUpdates(void);
	
	
	/// Get the timer duration during the last update
	/**
	 *	Useful for determining the amount of time which elapsed during the last update
	 *	can be used to accurately control values with a per-second rate or determine the current frame rate.
	 *  \return Duration of time between the last two calls to update() in milliseconds
	 */
	unsigned long lastUpdateMilliseconds(void);
	/// Alias of lastUpdateMilliseconds() which returns time in seconds
	/**
	 *  \return Duration of time between the last two calls to update() in seconds
	 */
	double lastUpdateSeconds(void);

	
	/// Set the timer pause state
	/**
	 *  Pause the timer, allowing for continued update() calls without an increment in timing but
	 *	maintaining the update and total time count, useful for pausing a scene but allowing frame
	 *	timing to resume.
	 *  \param pause_in Value to set the current pause state to
	 */
	void paused(bool pause_in);
	
	/// Check if the timer is currently in a paused state
	/**
	 *  \return Current pause state, true if paused, false otherwise
	 */
	bool paused();
};


#endif