#include "frontends/common2/timer.h"

#include <ostream>
#include <cmath>
#include <iomanip>

Timer::Timer()
  : mySum(0)
  , mySum2(0)
  , myN(0)
{
  tic();
}

void Timer::tic()
{
  myT0 = std::chrono::steady_clock::now();
}

void Timer::toc()
{
  const auto now = std::chrono::steady_clock::now();
  const auto micros = std::chrono::duration_cast<std::chrono::microseconds>(now - myT0).count();
  const double s = micros * 0.000001;
  mySum += s;
  mySum2 += s * 2;
  ++myN;
  myT0 = now;
}

std::ostream& operator<<(std::ostream& os, const Timer & timer)
{
  const double m1 = timer.mySum / timer.myN;
  const double m2 = timer.mySum2 / timer.myN;
  const double std = std::sqrt(std::max(0.0, m2 - m1 * m1));
  const double scale = 1000;
  os << std::fixed << std::setprecision(2);
  os << "total = " << std::setw(9) << timer.mySum * scale;
  os << ", average = " << std::setw(9) << m1 * scale;
  os << ", std = " << std::setw(9) << std * scale;
  os << ", n = " << std::setw(6) << timer.myN;
  return os;
}