/* ----------------------------------------------------------------------
   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 "fix_my_momrot_chunk.h"
#include <cmath>
#include <cstring>
#include "atom.h"
#include "domain.h"
#include "update.h"
#include "force.h"
#include "modify.h"
#include "compute_chunk_atom.h"
#include "compute_com_chunk.h"
#include "compute_vcm_chunk.h"
#include "compute_omega_chunk.h"
#include "memory.h"
#include "error.h"

using namespace LAMMPS_NS;
using namespace FixConst;

#define SMALL 1.0e-10

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

FixMomentumChunk::FixMomentumChunk(LAMMPS *lmp, int narg, char **arg) :
  Fix(lmp, narg, arg),
  idchunk(NULL), idcom(NULL),idvcm(NULL),idomega(NULL)
{
  if (narg < 9) error->all(FLERR,"Illegal fix momentum/chun command");
  nevery = force->inumeric(FLERR,arg[3]);
  if (nevery <= 0) error->all(FLERR,"Illegal fix momentum/chun command");


   linear = angular= 0;

  int n = strlen(arg[4]) + 1;
  idchunk = new char[n];
  strcpy(idchunk,arg[4]);

  n = strlen(arg[5]) + 1;
  idcom = new char[n];
  strcpy(idcom,arg[5]);

  n = strlen(arg[6]) + 1;
  idvcm = new char[n];
  strcpy(idvcm,arg[6]);

  n = strlen(arg[7]) + 1;
  idomega = new char[n];
  strcpy(idomega,arg[7]); 

  int iarg = 8;
  while (iarg < narg)
    {
      if (strcmp(arg[iarg],"linear") == 0)
	{
	  linear = 1;
	   iarg += 1;
	}
      else if (strcmp(arg[iarg],"angular") == 0)
	{
	   angular = 1;
	   iarg += 1;
	} else error->all(FLERR,"Illegal fix momentum/chunk command");
    }

    if (linear == 0 && angular == 0)
    error->all(FLERR,"Illegal fix momentum/chunk command");

  nchunk = 0;
}

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

FixMomentumChunk::~FixMomentumChunk()
{

  // decrement lock counter in compute chunk/atom, it if still exists

  int icompute = modify->find_compute(idchunk);
  if (icompute >= 0) {
    cchunk = (ComputeChunkAtom *) modify->compute[icompute];
    cchunk->unlock(this);
    cchunk->lockcount--;
  }

  delete [] idchunk;
  delete [] idcom;
}

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

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

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

void FixMomentumChunk::init()
{
  // current indices for idchunk and idcom

  int icompute = modify->find_compute(idchunk);
  if (icompute < 0)
    error->all(FLERR,"Chunk/atom compute does not exist for fix momentum/chunk");
  cchunk = (ComputeChunkAtom *) modify->compute[icompute];
  if (strcmp(cchunk->style,"chunk/atom") != 0)
    error->all(FLERR,"Fix momentum/chunk does not use chunk/atom compute");

  icompute = modify->find_compute(idcom);
  if (icompute < 0)
    error->all(FLERR,"Com/chunk compute does not exist for fix momentum/chunk");
  ccom = (ComputeCOMChunk *) modify->compute[icompute];
  if (strcmp(ccom->style,"com/chunk") != 0)
    error->all(FLERR,"Fix momentum/chunk does not use com/chunk compute");

    icompute = modify->find_compute(idvcm);
  if (icompute < 0)
    error->all(FLERR,"vcm/chunk compute does not exist for fix momentum/chunk");
  cvcm = (ComputeVCMChunk *) modify->compute[icompute];
  if (strcmp(cvcm->style,"vcm/chunk") != 0)
    error->all(FLERR,"Fix momentum/chunk does not use vcm/chunk compute");

      icompute = modify->find_compute(idomega);
  if (icompute < 0)
    error->all(FLERR,"omega/chunk compute does not exist for fix momentum/chunk");
  comega = (ComputeOmegaChunk *) modify->compute[icompute];
  if (strcmp(comega->style,"omega/chunk") != 0)
    error->all(FLERR,"Fix momentum/chunk does not use omega/chunk compute");

  // check that idchunk is consistent with ccom->idchunk

  if (strcmp(idchunk,ccom->idchunk) != 0)
    error->all(FLERR,"Fix spring chunk chunkID not same as comID chunkID");

    // check that idchunk is consistent with cvcm->idchunk
  //idchunk is private data of VCM ad OMEGA, no check for them
  // if (strcmp(idchunk,cvcm->idchunk) != 0)
  //   error->all(FLERR,"Fix momentum chunk chunkID not same as vcmID chunkID");
  
  //   // check that idchunk is consistent with comega->idchunk

  // if (strcmp(idchunk,comega->idchunk) != 0)
  //   error->all(FLERR,"Fix momentum chunk chunkID not same as omegaID chunkID");

}


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

void FixMomentumChunk::end_of_step()
{
  int i,m;
  double dx,dy,dz;

  // calculate current centers of mass for each chunk
  // extract pointers from idchunk and idcom

  ccom->compute_array();
  cvcm->compute_array();
  comega->compute_array();

  nchunk = cchunk->nchunk;
  int *ichunk = cchunk->ichunk;
  double *masstotal = ccom->masstotal;
  double **com = ccom->array;
  double **vcm = cvcm->array;
  double **omega = comega->array;

 
  // apply removing translational and rotational velocity to atoms in each chunk

  double **v = atom->v;
  int *mask = atom->mask;
  const int nlocal = atom->nlocal;
  int *type = atom->type;
  double *mass = atom->mass;
  double *rmass = atom->rmass;

  if (linear) {
    for (i = 0; i < nlocal; i++) {
      m = ichunk[i]-1;
      if (m < 0) continue;
      v[i][0] -= vcm[m][0];
      v[i][1] -= vcm[m][1];
      v[i][2] -= vcm[m][2];
    }
  }

    if (angular) {
    // must use unwrapped coords to compute omega to v correctly
      double **x = atom->x;
      imageint *image = atom->image;
      double unwrap[3];

    for (i = 0; i < nlocal; i++) {
      m = ichunk[i]-1;
      if (m < 0) continue;
      domain->unmap(x[i],image[i],unwrap);
      dx = unwrap[0] - com[m][0];
      dy = unwrap[1] - com[m][1];
      dz = unwrap[2] - com[m][2];

      v[i][0] -= omega[m][1]*dz - omega[m][2]*dy;
      v[i][1] -= omega[m][2]*dx - omega[m][0]*dz;
      v[i][2] -= omega[m][0]*dy - omega[m][1]*dx;
    }    
    }
}