/** 
 * @file lltrace.h
 * @brief Runtime statistics accumulation.
 *
 * $LicenseInfo:firstyear=2001&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2012, Linden Research, Inc.
 * 
 * This library 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;
 * version 2.1 of the License only.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 * 
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */

#ifndef LL_LLTRACE_H
#define LL_LLTRACE_H

#include "stdtypes.h"
#include "llpreprocessor.h"

#include <vector>
#include <boost/type_traits/alignment_of.hpp>

namespace LLTrace
{
	//TODO figure out best way to do this and proper naming convention
	
	static 
	void init()
	{

	}

	template<typename T>
	class Accumulator
	{
	public:
		Accumulator()
		:	mSum(),
			mMin(),
			mMax(),
			mNumSamples(0)
		{}

		void sample(T value)
		{
			mNumSamples++;
			mSum += value;
			if (value < mMin)
			{
				mMin = value;
			}
			else if (value > mMax)
			{
				mMax = value;
			}
		}

	private:
		T	mSum,
			mMin,
			mMax;

		U32	mNumSamples;
	};

	class TraceStorage
	{
	protected:
		TraceStorage(const size_t size, const size_t alignment)
		{
			mRecordOffset = sNextOffset + (alignment - 1);
			mRecordOffset -= mRecordOffset % alignment;
			sNextOffset = mRecordOffset + size;
			sStorage.reserve((size_t)sNextOffset);
		}

		// this needs to be thread local
		static std::vector<U8>	sStorage;
		static ptrdiff_t		sNextOffset;

		ptrdiff_t				mRecordOffset;
	};

	std::vector<U8> TraceStorage::sStorage;
	ptrdiff_t TraceStorage::sNextOffset = 0;

	template<typename T>
	class Trace : public TraceStorage
	{
	public:
		Trace(const std::string& name)
		:	TraceStorage(sizeof(Accumulator<T>), boost::alignment_of<Accumulator<T> >::value),
			mName(name)
		{}

		void record(T value)
		{
			(reinterpret_cast<Accumulator<T>* >(sStorage + mRecordOffset))->sample(value);
		}

	private:
		std::string		mName;
	};

	template<typename T>
	class Stat : public Trace<T>
	{
	public:
		Stat(const char* name)
		:	Trace(name)
		{}
	};

	class BlockTimer : public Trace<U32>
	{
	public:
		BlockTimer(const char* name)
		:	Trace(name)
		{}

		struct Accumulator
		{
			U32 						mTotalTimeCounter,
										mChildTimeCounter,
										mCalls;
			Accumulator*				mParent;		// info for caller timer
			Accumulator*				mLastCaller;	// used to bootstrap tree construction
			const BlockTimer*			mTimer;			// points to block timer associated with this storage
			U8							mActiveCount;	// number of timers with this ID active on stack
			bool						mMoveUpTree;	// needs to be moved up the tree of timers at the end of frame
			std::vector<Accumulator*>	mChildren;		// currently assumed child timers
		};

		struct RecorderStackEntry
		{
			struct Recorder*	mRecorder;
			Accumulator*		mAccumulator;
			U32					mChildTime;
		};

		struct Recorder
		{
			LL_FORCE_INLINE Recorder(BlockTimer& block_timer)
			:	mLastRecorder(sCurRecorder)
			{
				mStartTime = getCPUClockCount32();
				Accumulator* accumulator = ???; // get per-thread accumulator
				accumulator->mActiveCount++;
				accumulator->mCalls++;
				accumulator->mMoveUpTree |= (accumulator->mParent->mActiveCount == 0);

				// push new timer on stack
				sCurRecorder.mRecorder = this;
				sCurRecorder.mAccumulator = accumulator;
				sCurRecorder.mChildTime = 0;
			}

			LL_FORCE_INLINE ~Recorder()
			{
				U32 total_time = getCPUClockCount32() - mStartTime;

				Accumulator* accumulator = sCurRecorder.mAccumulator;
				accumulator->mTotalTimeCounter += total_time;
				accumulator->mChildTimeCounter += sCurRecorder.mChildTime;
				accumulator->mActiveCount--;

				accumulator->mLastCaller = mLastRecorder.mAccumulator;
				mLastRecorder.mChildTime += total_time;

				// pop stack
				sCurRecorder = mLastRecorder;
			}

			RecorderStackEntry mLastRecorder;
			U32 mStartTime;
		};

	private:
		static U32 getCPUClockCount32()
		{
			U32 ret_val;
			__asm
			{
				_emit   0x0f
					_emit   0x31
					shr eax,8
					shl edx,24
					or eax, edx
					mov dword ptr [ret_val], eax
			}
			return ret_val;
		}

		// return full timer value, *not* shifted by 8 bits
		static U64 getCPUClockCount64()
		{
			U64 ret_val;
			__asm
			{
				_emit   0x0f
					_emit   0x31
					mov eax,eax
					mov edx,edx
					mov dword ptr [ret_val+4], edx
					mov dword ptr [ret_val], eax
			}
			return ret_val;
		}

		static RecorderStackEntry sCurRecorder;
	};

	BlockTimer::RecorderStackEntry BlockTimer::sCurRecorder;

	class TimeInterval 
	{
	public:
		void start() {}
		void stop() {}
		void resume() {}
	};

	class SamplingTimeInterval
	{
	public:
		void start() {}
		void stop() {}
		void resume() {}
	};

}

#define TOKEN_PASTE_ACTUAL(x, y) x##y
#define TOKEN_PASTE(x, y) TOKEN_PASTE_ACTUAL(x, y)
#define RECORD_BLOCK_TIME(block_timer) LLTrace::BlockTimer::Recorder TOKEN_PASTE(block_time_recorder, __COUNTER__)(block_timer);

#endif // LL_LLTRACE_H