/* ----------------------------------------------------------------------
   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.
------------------------------------------------------------------------- */

/* ----------------------------------------------------------------------
   Contributing author: Carsten Svaneborg (SDU)
------------------------------------------------------------------------- */

#include <math.h>
#include <stdlib.h>
#include <string.h>
#include "angle_zero.h"
#include "atom.h"
#include "force.h"
#include "comm.h"
#include "math_const.h"
#include "memory.h"
#include "error.h"

using namespace LAMMPS_NS;
using namespace MathConst;

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

AngleZero::AngleZero(LAMMPS *lmp) : Angle(lmp), coeffflag(1) {}

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

AngleZero::~AngleZero()
{
  if (allocated && !copymode) {
    memory->destroy(setflag);
    memory->destroy(theta0);
  }
}

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

void AngleZero::compute(int eflag, int vflag)
{
  if (eflag || vflag) ev_setup(eflag,vflag);
  else evflag = 0;
}

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

void AngleZero::settings(int narg, char **arg)
{
  if ((narg != 0) && (narg != 1))
    error->all(FLERR,"Illegal angle_style command");

  if (narg == 1) {
    if (strcmp("nocoeff",arg[0]) == 0) coeffflag=0;
    else error->all(FLERR,"Illegal angle_style command");
  }
}

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

void AngleZero::allocate()
{
  allocated = 1;
  int n = atom->nangletypes;

  memory->create(theta0,n+1,"angle:theta0");
  memory->create(setflag,n+1,"angle:setflag");
  for (int i = 1; i <= n; i++) setflag[i] = 0;
}

/* ----------------------------------------------------------------------
   set coeffs for one or more types
------------------------------------------------------------------------- */

void AngleZero::coeff(int narg, char **arg)
{
  if ((narg < 1) || (coeffflag && narg > 2))
    error->all(FLERR,"Incorrect args for angle coefficients");

  if (!allocated) allocate();

  int ilo,ihi;
  force->bounds(FLERR,arg[0],atom->nangletypes,ilo,ihi);

  double theta0_one = 0.0;
  if (coeffflag && (narg == 2))
    theta0_one = force->numeric(FLERR,arg[1]);

  // convert theta0 from degrees to radians

  int count = 0;
  for (int i = ilo; i <= ihi; i++) {
    setflag[i] = 1;
    theta0[i] = theta0_one/180.0 * MY_PI;
    count++;
  }

  if (count == 0) error->all(FLERR,"Incorrect args for angle coefficients");
}

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

double AngleZero::equilibrium_angle(int i)
{
  return theta0[i];
}

/* ----------------------------------------------------------------------
   proc 0 writes out coeffs to restart file
------------------------------------------------------------------------- */

void AngleZero::write_restart(FILE *fp) {
  fwrite(&theta0[1],sizeof(double),atom->nangletypes,fp);
}

/* ----------------------------------------------------------------------
   proc 0 reads coeffs from restart file, bcasts them
------------------------------------------------------------------------- */

void AngleZero::read_restart(FILE *fp)
{
  allocate();

  if (comm->me == 0) {
    fread(&theta0[1],sizeof(double),atom->nangletypes,fp);
  }
  MPI_Bcast(&theta0[1],atom->nangletypes,MPI_DOUBLE,0,world);

  for (int i = 1; i <= atom->nangletypes; i++) setflag[i] = 1;
}
/* ----------------------------------------------------------------------
   proc 0 writes to data file
------------------------------------------------------------------------- */

void AngleZero::write_data(FILE *fp)
{
  for (int i = 1; i <= atom->nangletypes; i++)
    fprintf(fp,"%d %g\n",i,theta0[i]/MY_PI*180.0);
}

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

double AngleZero::single(int type, int i1, int i2, int i3)
{
  return 0.0;
}