/* ----------------------------------------------------------------------
   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.
   Created from fix_ave_atom.cpp by Bartosz Liedke b.liedke@hzdr.de
------------------------------------------------------------------------- */

#include "stdlib.h"
#include "string.h"
#include "fix_resetflag_atom.h"
#include "atom.h"
#include "domain.h"
#include "update.h"
#include "modify.h"
#include "compute.h"
#include "input.h"
#include "variable.h"
#include "memory.h"
#include "error.h"
#include "force.h"

using namespace LAMMPS_NS;
using namespace FixConst;

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

FixResetFlagAtom::FixResetFlagAtom(LAMMPS *lmp, int narg, char **arg) :
  Fix(lmp, narg, arg)
{
  if (narg < 3) error->all(FLERR,"Illegal fix resetflag/atom command");

  peratom_freq = force->inumeric(FLERR,arg[3]);
  nrepeat = 1;
  nevery = peratom_freq;


  // nvalid = next step on which end_of_step does something

  irepeat = 0;
  nvalid = nextvalid();

}

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

FixResetFlagAtom::~FixResetFlagAtom()
{
  // unregister callback to this fix from Atom class

  atom->delete_callback(id,0);

}

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

int FixResetFlagAtom::setmask()
{
  int mask = 0;
  mask |= END_OF_STEP;
  return mask;
}

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

void FixResetFlagAtom::init()
{
 
  // need to reset nvalid if nvalid < ntimestep b/c minimize was performed

  if (nvalid < update->ntimestep) {
    irepeat = 0;
    nvalid = nextvalid();
  }
}

/* ----------------------------------------------------------------------
   only does something if nvalid = current timestep
------------------------------------------------------------------------- */

void FixResetFlagAtom::setup(int vflag)
{
  end_of_step();
}

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

void FixResetFlagAtom::end_of_step()
{
  int i;

  // skip if not step which requires doing something
  bigint ntimestep = update->ntimestep;
  if (ntimestep != nvalid) return;

  int nlocal = atom->nlocal;
  int *mask = atom->mask;
  // here it goes through each atom and resets the image flag
  for (i = 0; i < nlocal; i++)
	if (mask[i] & groupbit) 
		atom->image[i] = ( (tagint) IMGMAX & IMGMASK) | 
			(( (tagint) IMGMAX & IMGMASK) << IMGBITS) | 
			(( (tagint) IMGMAX & IMGMASK) << IMG2BITS);
			


  irepeat = 0;
  nvalid = ntimestep+peratom_freq;
}


/* ----------------------------------------------------------------------
   calculate nvalid = next step on which end_of_step does something
------------------------------------------------------------------------- */

bigint FixResetFlagAtom::nextvalid()
{
  bigint nvalid = (update->ntimestep/peratom_freq)*peratom_freq + peratom_freq;

  if (nvalid-peratom_freq == update->ntimestep )
    nvalid = update->ntimestep;
  if (nvalid < update->ntimestep) nvalid += peratom_freq;
  return nvalid;
}

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

void FixResetFlagAtom::reset_timestep(bigint ntimestep)
{
  if (ntimestep > nvalid) error->all(FLERR,"Fix resetflag/atom missed timestep");
}