///////////////////////////////////////////////////////////////////////////////
// LameXP - Audio Encoder Front-End
// Copyright (C) 2004-2011 LoRd_MuldeR <MuldeR2@GMX.de>
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program 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 General Public License along
// with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
// http://www.gnu.org/licenses/gpl-2.0.txt
///////////////////////////////////////////////////////////////////////////////

#include "Thread_CPUObserver.h"
#include "Global.h"

#include <QDir>
#include <QLibrary>

typedef BOOL (WINAPI *GetSystemTimesPtr)(LPFILETIME lpIdleTime, LPFILETIME lpKernelTime, LPFILETIME lpUserTime);

////////////////////////////////////////////////////////////
// Constructor & Destructor
////////////////////////////////////////////////////////////

CPUObserverThread::CPUObserverThread(void)
{
	m_terminated = false;
}

CPUObserverThread::~CPUObserverThread(void)
{
}

////////////////////////////////////////////////////////////
// Protected functions
////////////////////////////////////////////////////////////

void CPUObserverThread::run(void)
{
	qDebug("CPU observer started!");
	m_terminated = false;

	try
	{
		observe();
	}
	catch(...)
	{
		fflush(stdout);
		fflush(stderr);
		fprintf(stderr, "\nGURU MEDITATION !!!\n");
		FatalAppExit(0, L"Unhandeled exception error, application will exit!");
		TerminateProcess(GetCurrentProcess(), -1);
	}
}

ULONGLONG CPUObserverThread::filetime2ulonglong(const void *ftime)
{
	ULARGE_INTEGER tmp; tmp.QuadPart = 0UI64;
	const FILETIME* fileTime = reinterpret_cast<const FILETIME*>(ftime);
	tmp.LowPart = fileTime->dwLowDateTime;
	tmp.HighPart = fileTime->dwHighDateTime;
	return tmp.QuadPart;
}

void CPUObserverThread::observe(void)
{
	QLibrary kernel32("kernel32.dll");
	GetSystemTimesPtr getSystemTimes = NULL;

	if(kernel32.load())
	{
		getSystemTimes = reinterpret_cast<GetSystemTimesPtr>(kernel32.resolve("GetSystemTimes"));
	}

	if(getSystemTimes != NULL)
	{
		bool first = true;
		double previous = -1.0;
		FILETIME sysTime, usrTime, idlTime;
		ULONGLONG sys[2], usr[2], idl[2];

		for(size_t i = 0; i < 2; i++)
		{
			sys[i] = 0; usr[i] = 0; idl[i] = 0;
		}

		while(!m_terminated)
		{
			if(getSystemTimes(&idlTime, &sysTime, &usrTime))
			{
				sys[1] = sys[0]; sys[0] = filetime2ulonglong(&sysTime);
				usr[1] = usr[0]; usr[0] = filetime2ulonglong(&usrTime);
				idl[1] = idl[0]; idl[0] = filetime2ulonglong(&idlTime);

				if(first)
				{
					first = false;
					emit currentUsageChanged(1.0);
					msleep(250);
					continue;
				}

				ULONGLONG timeIdl = (idl[0] - idl[1]); //Idle time only
				ULONGLONG timeSys = (sys[0] - sys[1]); //Kernel mode time (incl. Idle time!)
				ULONGLONG timeUsr = (usr[0] - usr[1]); //User mode time only
				
				ULONGLONG timeSum = timeUsr + timeSys; //Overall CPU time that has elapsed
				ULONGLONG timeWrk = timeSum - timeIdl; //Time the CPU spent working

				if(timeSum > 0)
				{
					double current = static_cast<double>(timeWrk) / static_cast<double>(timeSum);
					if(current != previous)
					{
						emit currentUsageChanged(current);
						previous = current;
					}
				}
			}
			msleep(1000);
		}
	}
	else
	{
		qWarning("GetSystemTimes() ist not available on this system!");
	}
}

////////////////////////////////////////////////////////////
// SLOTS
////////////////////////////////////////////////////////////

/*NONE*/

////////////////////////////////////////////////////////////
// EVENTS
////////////////////////////////////////////////////////////

/*NONE*/