/** 
 * @file llstat.h
 * @brief Runtime statistics accumulation.
 *
 * Copyright (c) 2001-$CurrentYear$, Linden Research, Inc.
 * $License$
 */

#ifndef LL_LLSTAT_H
#define LL_LLSTAT_H

#include <deque>

#include "lltimer.h"
#include "llframetimer.h"

//
// Accumulates statistics for an arbitrary length of time.
// Does this by maintaining a chain of accumulators, each one
// accumulation the results of the parent.  Can scale to arbitrary
// amounts of time with very low memory cost.
//

class LLStatAccum
{
protected:
	LLStatAccum(bool use_frame_timer);
	virtual ~LLStatAccum();

public:
	enum TimeScale {
		SCALE_SECOND,
		SCALE_MINUTE,
		SCALE_TWO_MINUTE,
		SCALE_HOUR,
		SCALE_DAY,
		SCALE_WEEK,

		NUM_SCALES
	};

	F32 meanValue(TimeScale scale) const;
		// see the subclasses for the specific meaning of value

	F32 meanValueOverLastSecond() const	{ return meanValue(SCALE_SECOND); }
	F32 meanValueOverLastMinute() const	{ return meanValue(SCALE_MINUTE); }

protected:
	class impl;
	impl& m;
};

class LLStatMeasure : public LLStatAccum
	// gathers statistics about things that are measured
	// ex.: tempature, time dilation
{
public:
	LLStatMeasure(bool use_frame_timer = true);

	void sample(F64);
	void sample(S32 v) { sample((F64)v); }
	void sample(U32 v) { sample((F64)v); }
	void sample(S64 v) { sample((F64)v); }
	void sample(U64 v) { sample((F64)v); }
};


class LLStatRate : public LLStatAccum
	// gathers statistics about things that can be counted over time
	// ex.: LSL instructions executed, messages sent, simulator frames completed
	// renders it in terms of rate of thing per second
{
public:
	LLStatRate(bool use_frame_timer = true);

	void count(U32);
		// used to note that n items have occured
	
	void mark() { count(1); }
		// used for counting the rate thorugh a point in the code
};


class LLTimeBlock;

class LLStatTime : public LLStatAccum
	// gathers statistics about time spent in a block of code
	// measure average duration per second in the block
{
public:
	LLStatTime(bool use_frame_timer = false);

private:
	void start();
	void stop();
	friend class LLTimeBlock;
};

class LLTimeBlock
{
public:
	LLTimeBlock(LLStatTime& stat) : mStat(stat) { mStat.start(); }
	~LLTimeBlock()								{ mStat.stop(); }
private:
	LLStatTime& mStat;
};





class LLStat
{
public:
	LLStat(const U32 num_bins = 32, BOOL use_frame_timer = FALSE);
	~LLStat();

	void reset();

	void start();	// Start the timer for the current "frame", otherwise uses the time tracked from
					// the last addValue
	void addValue(const F32 value = 1.f); // Adds the current value being tracked, and tracks the DT.
	void addValue(const S32 value) { addValue((F32)value); }
	void addValue(const U32 value) { addValue((F32)value); }

	void setBeginTime(const F64 time);
	void addValueTime(const F64 time, const F32 value = 1.f);
	
	S32 getCurBin() const;
	S32 getNextBin() const;
	
	F32 getCurrent() const;
	F32 getCurrentPerSec() const;
	F64 getCurrentBeginTime() const;
	F64 getCurrentTime() const;
	F32 getCurrentDuration() const;
	
	F32 getPrev(S32 age) const;				// Age is how many "addValues" previously - zero is current
	F32 getPrevPerSec(S32 age) const;		// Age is how many "addValues" previously - zero is current
	F64 getPrevBeginTime(S32 age) const;
	F64 getPrevTime(S32 age) const;
	
	F32 getBin(S32 bin) const;
	F32 getBinPerSec(S32 bin) const;
	F64 getBinBeginTime(S32 bin) const;
	F64 getBinTime(S32 bin) const;

	F32 getMax() const;
	F32 getMaxPerSec() const;
	
	F32 getMean() const;
	F32 getMeanPerSec() const;
	F32 getMeanDuration() const;

	F32 getMin() const;
	F32 getMinPerSec() const;
	F32 getMinDuration() const;

	F32 getSum() const;
	F32 getSumDuration() const;

	U32 getNumValues() const;
	S32 getNumBins() const;

	F64 getLastTime() const;
private:
	BOOL mUseFrameTimer;
	U32 mNumValues;
	U32 mNumBins;
	F32 mLastValue;
	F64 mLastTime;
	F32 *mBins;
	F64 *mBeginTime;
	F64 *mTime;
	F32 *mDT;
	S32 mCurBin;
	S32 mNextBin;
	static LLTimer sTimer;
	static LLFrameTimer sFrameTimer;
};

#endif // LL_STAT_
