#ifndef TIMER_H_DEF
#define TIMER_H_DEF

#ifdef WIN32   // Windows system specific
#include <windows.h>
#else          // Unix based system specific
#include <sys/time.h>
#endif

class Timer {
    public:
        Timer();
        ~Timer();
        void start();
        void stop();
        double getElapsedTime();
        double getElapsedTimeInSec();
        double getElapsedTimeInMilliSec();
        double getElapsedTimeInMicroSec();

    private:
        double startTimeInMicroSec;
        double endTimeInMicroSec;
        int stopped;
    #ifdef WIN32
        LARGE_INTEGER frequency;
        LARGE_INTEGER startCount;
        LARGE_INTEGER endCount;
    #else
        timeval startCount;
        timeval endCount;
    #endif
};

Timer::Timer(){
    #ifdef WIN32
    QueryPerformanceFrequency(&frequency);
    startCount.QuadPart = 0;
    endCount.QuadPart = 0;
    #else
    startCount.tv_sec = startCount.tv_usec = 0;
    endCount.tv_sec = endCount.tv_usec = 0;
    #endif
    stopped = 0;
    startTimeInMicroSec = 0;
    endTimeInMicroSec = 0;
}


Timer::~Timer(){}

void Timer::start(){
    stopped = 0;
    #ifdef WIN32
    QueryPerformanceCounter(&startCount);
    #else
    gettimeofday(&startCount, NULL);
    #endif
}

void Timer::stop(){
    stopped = 1; // set timer stopped flag
    #ifdef WIN32
    QueryPerformanceCounter(&endCount);
    #else
    gettimeofday(&endCount, NULL);
    #endif
}

double Timer::getElapsedTimeInMicroSec(){
    #ifdef WIN32
    if(!stopped) QueryPerformanceCounter(&endCount);
    startTimeInMicroSec = startCount.QuadPart * (1000000.0 / frequency.QuadPart);
    endTimeInMicroSec = endCount.QuadPart * (1000000.0 / frequency.QuadPart);
    #else
    if(!stopped) gettimeofday(&endCount, NULL);
    startTimeInMicroSec = (startCount.tv_sec * 1000000.0) + startCount.tv_usec;
    endTimeInMicroSec = (endCount.tv_sec * 1000000.0) + endCount.tv_usec;
    #endif
    return endTimeInMicroSec - startTimeInMicroSec;
}

double Timer::getElapsedTimeInMilliSec(){
    return this->getElapsedTimeInMicroSec() * 0.001;
}

double Timer::getElapsedTimeInSec(){
    return this->getElapsedTimeInMicroSec() * 0.000001;
}

double Timer::getElapsedTime(){
    return this->getElapsedTimeInSec();
}

#endif // TIMER_H_DEF