/* ----------------------------------------------------------------------
   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
   http://lammps.sandia.gov, Sandia National Laboratories
   Steve Plimpton, sjplimp@sandia.gov

   Copyright (2003) Sandia Corporation.  Under the terms of Contract
   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
   certain rights in this software.  This software is distributed under
   the GNU General Public License.

   See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */

#include <mpi.h>
#include "imbalance_time.h"
#include "atom.h"
#include "comm.h"
#include "force.h"
#include "timer.h"
#include "error.h"

using namespace LAMMPS_NS;

/* -------------------------------------------------------------------- */

ImbalanceTime::ImbalanceTime(LAMMPS *lmp) : Imbalance(lmp) {}

/* -------------------------------------------------------------------- */

int ImbalanceTime::options(int narg, char **arg)
{
  if (narg < 1) error->all(FLERR,"Illegal balance weight command");
  factor = force->numeric(FLERR,arg[0]);
  if (factor < 0.0) error->all(FLERR,"Illegal balance weight command");
  return 1;
}

/* ----------------------------------------------------------------------
   reset last, needed for fix balance caller
------------------------------------------------------------------------- */

void ImbalanceTime::init()
{
  last = 0.0;
}

/* -------------------------------------------------------------------- */

void ImbalanceTime::compute(double *weight)
{
  const int nlocal = atom->nlocal;
  const bigint natoms = atom->natoms;

  if (factor == 0.0) return;

  // compute the cost function of based on relevant timers
  
  if (timer->has_normal()) {
      double cost = -last;
      cost += timer->get_wall(Timer::PAIR);
      cost += timer->get_wall(Timer::NEIGH);
      cost += timer->get_wall(Timer::BOND);
      cost += timer->get_wall(Timer::KSPACE);

      double allcost;
      MPI_Allreduce(&cost,&allcost,1,MPI_DOUBLE,MPI_SUM,world);

      if ((allcost > 0.0) && (nlocal > 0)) {
        const double avgcost = allcost/natoms;
        const double localcost = cost/nlocal;
        const double scale = (1.0-factor) + factor*localcost/avgcost;
        for (int i = 0; i < nlocal; ++i) weight[i] *= scale;
      }

      // record time up to this point

      last += cost;
  }
}

/* -------------------------------------------------------------------- */

void ImbalanceTime::info(FILE *fp)
{
  fprintf(fp,"  time weight factor: %g\n",factor);
}