/* ----------------------------------------------------------------------
   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 "lmptype.h"
#include "mpi.h"
#include "string.h"
#include "stdlib.h"
//#include "sys/types.h"
#include "dirent.h"
#include "read_restart.h"
#include "atom.h"
#include "atom_vec.h"
#include "domain.h"
#include "comm.h"
#include "irregular.h"
#include "update.h"
#include "modify.h"
#include "fix.h"
#include "fix_read_restart.h"
#include "group.h"
#include "force.h"
#include "pair.h"
#include "bond.h"
#include "angle.h"
#include "dihedral.h"
#include "improper.h"
#include "special.h"
#include "universe.h"
#include "memory.h"
#include "error.h"

using namespace LAMMPS_NS;

// same as write_restart.cpp

enum{VERSION,SMALLINT,TAGINT,BIGINT,
       UNITS,NTIMESTEP,DIMENSION,NPROCS,PROCGRID_0,PROCGRID_1,PROCGRID_2,
       NEWTON_PAIR,NEWTON_BOND,XPERIODIC,YPERIODIC,ZPERIODIC,
       BOUNDARY_00,BOUNDARY_01,BOUNDARY_10,BOUNDARY_11,BOUNDARY_20,BOUNDARY_21,
       ATOM_STYLE,NATOMS,NTYPES,
       NBONDS,NBONDTYPES,BOND_PER_ATOM,
       NANGLES,NANGLETYPES,ANGLE_PER_ATOM,
       NDIHEDRALS,NDIHEDRALTYPES,DIHEDRAL_PER_ATOM,
       NIMPROPERS,NIMPROPERTYPES,IMPROPER_PER_ATOM,
       BOXLO_0,BOXHI_0,BOXLO_1,BOXHI_1,BOXLO_2,BOXHI_2,
       SPECIAL_LJ_1,SPECIAL_LJ_2,SPECIAL_LJ_3,
       SPECIAL_COUL_1,SPECIAL_COUL_2,SPECIAL_COUL_3,
       XY,XZ,YZ};
enum{MASS};
enum{PAIR,BOND,ANGLE,DIHEDRAL,IMPROPER};

#define LB_FACTOR 1.1

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

ReadRestart::ReadRestart(LAMMPS *lmp) : Pointers(lmp) {}

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

void ReadRestart::command(int narg, char **arg)
{
  if (narg != 1) error->all(FLERR,"Illegal read_restart command");

  if (domain->box_exist)
    error->all(FLERR,"Cannot read_restart after simulation box is defined");

  MPI_Comm_rank(world,&me);
  MPI_Comm_size(world,&nprocs);

  // if filename contains "*", search dir for latest restart file

  char *file = new char[strlen(arg[0]) + 16];
  if (strchr(arg[0],'*')) {
    int n;
    if (me == 0) {
      file_search(arg[0],file);
      n = strlen(file) + 1;
    }
    MPI_Bcast(&n,1,MPI_INT,0,world);
    MPI_Bcast(file,n,MPI_CHAR,0,world);
  } else strcpy(file,arg[0]);

  // check if filename contains "%"

  int multiproc;
  if (strchr(file,'%')) multiproc = 1;
  else multiproc = 0;

  // open single restart file or base file for multiproc case
  // auto-detect whether byte swapping needs to be done as file is read

  if (me == 0) {
    if (screen) fprintf(screen,"Reading restart file ...\n");
    char *hfile;
    if (multiproc) {
      hfile = new char[strlen(file) + 16];
      char *ptr = strchr(file,'%');
      *ptr = '\0';
      sprintf(hfile,"%s%s%s",file,"base",ptr+1);
      *ptr = '%';
    } else hfile = file;
    fp = fopen(hfile,"rb");
    if (fp == NULL) {
      char str[128];
      sprintf(str,"Cannot open restart file %s",hfile);
      error->one(FLERR,str);
    }
    swapflag = autodetect(&fp,hfile);
    if (multiproc) delete [] hfile;
  }

  MPI_Bcast(&swapflag,1,MPI_INT,0,world);

  // read header info and create atom style and simulation box

  header();
  domain->box_exist = 1;

  // problem setup using info from header

  int n;
  if (nprocs == 1) n = static_cast<int> (atom->natoms);
  else n = static_cast<int> (LB_FACTOR * atom->natoms / nprocs);

  atom->allocate_type_arrays();
  atom->avec->grow(n);
  n = atom->nmax;

  domain->print_box("  ");
  domain->set_initial_box();
  domain->set_global_box();
  comm->set_proc_grid();
  domain->set_local_box();

  // read groups, ntype-length arrays, force field, fix info from file
  // nextra = max # of extra quantities stored with each atom

  group->read_restart(fp);
  type_arrays();
  force_fields();

  int nextra = modify->read_restart(fp);
  atom->nextra_store = nextra;
  memory->create(atom->extra,n,nextra,"atom:extra");

  // single file:
  // nprocs_file = # of chunks in file
  // proc 0 reads chunks one at a time and bcasts it to other procs
  // each proc unpacks the atoms, saving ones in it's sub-domain
  // check for atom in sub-domain differs for orthogonal vs triclinic box
  // close restart file when done

  AtomVec *avec = atom->avec;

  int maxbuf = 0;
  double *buf = NULL;
  int m;

  if (multiproc == 0) {
    int triclinic = domain->triclinic;
    double *x,lamda[3];
    double *coord,*sublo,*subhi;
    if (triclinic == 0) {
      sublo = domain->sublo;
      subhi = domain->subhi;
    } else {
      sublo = domain->sublo_lamda;
      subhi = domain->subhi_lamda;
    }

    for (int iproc = 0; iproc < nprocs_file; iproc++) {
      n = read_int();
      if (n > maxbuf) {
        maxbuf = n;
        memory->destroy(buf);
        memory->create(buf,maxbuf,"read_restart:buf");
      }

      if (n > 0) {
        if (me == 0) nread_double(buf,n,fp);
        MPI_Bcast(buf,n,MPI_DOUBLE,0,world);
      }

      m = 0;
      while (m < n) {
        x = &buf[m+1];
        if (triclinic) {
          domain->x2lamda(x,lamda);
          coord = lamda;
        } else coord = x;

        if (coord[0] >= sublo[0] && coord[0] < subhi[0] &&
            coord[1] >= sublo[1] && coord[1] < subhi[1] &&
            coord[2] >= sublo[2] && coord[2] < subhi[2]) {
          m += avec->unpack_restart(&buf[m]);
        }
        else m += static_cast<int> (buf[m]);
      }
    }

    if (me == 0) fclose(fp);

  // one file per proc:
  // nprocs_file = # of files
  // each proc reads 1/P fraction of files, keeping all atoms in the files
  // perform irregular comm to migrate atoms to correct procs
  // close restart file when done

  } else {
    if (me == 0) fclose(fp);
    char *perproc = new char[strlen(file) + 16];
    char *ptr = strchr(file,'%');

    for (int iproc = me; iproc < nprocs_file; iproc += nprocs) {
      *ptr = '\0';
      sprintf(perproc,"%s%d%s",file,iproc,ptr+1);
      *ptr = '%';
      fp = fopen(perproc,"rb");
      if (fp == NULL) {
        char str[128];
        sprintf(str,"Cannot open restart file %s",perproc);
        error->one(FLERR,str);
      }

      nread_int(&n,1,fp);
      if (n > maxbuf) {
        maxbuf = n;
        memory->destroy(buf);
        memory->create(buf,maxbuf,"read_restart:buf");
      }
      if (n > 0) nread_double(buf,n,fp);

      m = 0;
      while (m < n) m += avec->unpack_restart(&buf[m]);
      fclose(fp);
    }

    delete [] perproc;

    // create a temporary fix to hold and migrate extra atom info
    // necessary b/c irregular will migrate atoms

    if (nextra) {
      char cextra[8],fixextra[8];
      sprintf(cextra,"%d",nextra);
      sprintf(fixextra,"%d",modify->nfix_restart_peratom);
      char **newarg = new char*[5];
      newarg[0] = (char *) "_read_restart";
      newarg[1] = (char *) "all";
      newarg[2] = (char *) "READ_RESTART";
      newarg[3] = cextra;
      newarg[4] = fixextra;
      modify->add_fix(5,newarg);
      delete [] newarg;
    }

    // move atoms to new processors via irregular()
    // in case read by different proc than wrote restart file
    // first do map_init() since irregular->migrate_atoms() will do map_clear()

    if (atom->map_style) atom->map_init();
    if (domain->triclinic) domain->x2lamda(atom->nlocal);
    Irregular *irregular = new Irregular(lmp);
    irregular->migrate_atoms();
    delete irregular;
    if (domain->triclinic) domain->lamda2x(atom->nlocal);

    // put extra atom info held by fix back into atom->extra
    // destroy temporary fix

    if (nextra) {
      memory->destroy(atom->extra);
      memory->create(atom->extra,atom->nmax,nextra,"atom:extra");
      int ifix = modify->find_fix("_read_restart");
      FixReadRestart *fix = (FixReadRestart *) modify->fix[ifix];
      int *count = fix->count;
      double **extra = fix->extra;
      double **atom_extra = atom->extra;
      int nlocal = atom->nlocal;
      for (int i = 0; i < nlocal; i++)
        for (int j = 0; j < count[i]; j++)
          atom_extra[i][j] = extra[i][j];
      modify->delete_fix("_read_restart");
    }
  }

  // clean-up memory

  delete [] file;
  memory->destroy(buf);

  // check that all atoms were assigned to procs

  bigint natoms;
  bigint nblocal = atom->nlocal;
  MPI_Allreduce(&nblocal,&natoms,1,MPI_LMP_BIGINT,MPI_SUM,world);

  if (me == 0) {
    if (screen) fprintf(screen,"  " BIGINT_FORMAT " atoms\n",natoms);
    if (logfile) fprintf(logfile,"  " BIGINT_FORMAT " atoms\n",natoms);
  }

  if (natoms != atom->natoms)
    error->all(FLERR,"Did not assign all atoms correctly");

  if (me == 0) {
    if (atom->nbonds) {
      if (screen) fprintf(screen,"  " BIGINT_FORMAT " bonds\n",atom->nbonds);
      if (logfile) fprintf(logfile,"  " BIGINT_FORMAT " bonds\n",atom->nbonds);
    }
    if (atom->nangles) {
      if (screen) fprintf(screen,"  " BIGINT_FORMAT " angles\n",
                          atom->nangles);
      if (logfile) fprintf(logfile,"  " BIGINT_FORMAT " angles\n",
                           atom->nangles);
    }
    if (atom->ndihedrals) {
      if (screen) fprintf(screen,"  " BIGINT_FORMAT " dihedrals\n",
                          atom->ndihedrals);
      if (logfile) fprintf(logfile,"  " BIGINT_FORMAT " dihedrals\n",
                           atom->ndihedrals);
    }
    if (atom->nimpropers) {
      if (screen) fprintf(screen,"  " BIGINT_FORMAT " impropers\n",
                          atom->nimpropers);
      if (logfile) fprintf(logfile,"  " BIGINT_FORMAT " impropers\n",
                           atom->nimpropers);
    }
  }

  // check if tags are being used
  // create global mapping and bond topology now that system is defined

  int flag = 0;
  for (int i = 0; i < atom->nlocal; i++)
    if (atom->tag[i] > 0) flag = 1;
  int flag_all;
  MPI_Allreduce(&flag,&flag_all,1,MPI_INT,MPI_MAX,world);
  if (atom->natoms > 0 && flag_all == 0) atom->tag_enable = 0;

  if (atom->map_style) {
    atom->map_init();
    atom->map_set();
  }
  if (atom->molecular) {
    Special special(lmp);
    special.build();
  }
}

/* ----------------------------------------------------------------------
   infile contains a "*"
   search for all files which match the infile pattern
   replace "*" with latest timestep value to create outfile name
   search dir referenced by initial pathname of file
   if infile also contains "%", use "base" when searching directory
   only called by proc 0
------------------------------------------------------------------------- */

void ReadRestart::file_search(char *infile, char *outfile)
{
  char *ptr;

  // separate infile into dir + filename

  char *dirname = new char[strlen(infile) + 1];
  char *filename = new char[strlen(infile) + 1];

  if (strchr(infile,'/')) {
    ptr = strrchr(infile,'/');
    *ptr = '\0';
    strcpy(dirname,infile);
    strcpy(filename,ptr+1);
    *ptr = '/';
  } else {
    strcpy(dirname,"./");
    strcpy(filename,infile);
  }

  // if filename contains "%" replace "%" with "base"

  char *pattern = new char[strlen(filename) + 16];

  if (ptr = strchr(filename,'%')) {
    *ptr = '\0';
    sprintf(pattern,"%s%s%s",filename,"base",ptr+1);
    *ptr = '%';
  } else strcpy(pattern,filename);

  // scan all files in directory, searching for files that match pattern
  // maxnum = largest int that matches "*"

  int n = strlen(pattern) + 16;
  char *begin = new char[n];
  char *middle = new char[n];
  char *end = new char[n];

  ptr = strchr(pattern,'*');
  *ptr = '\0';
  strcpy(begin,pattern);
  strcpy(end,ptr+1);
  int nbegin = strlen(begin);
  bigint maxnum = -1;

  struct dirent *ep;
  DIR *dp = opendir(dirname);
  if (dp == NULL)
    error->one(FLERR,"Cannot open dir to search for restart file");
  while (ep = readdir(dp)) {
    if (strstr(ep->d_name,begin) != ep->d_name) continue;
    if ((ptr = strstr(&ep->d_name[nbegin],end)) == NULL) continue;
    if (strlen(end) == 0) ptr = ep->d_name + strlen(ep->d_name);
    *ptr = '\0';
    if (strlen(&ep->d_name[nbegin]) < n) {
      strcpy(middle,&ep->d_name[nbegin]);
      if (ATOBIGINT(middle) > maxnum) maxnum = ATOBIGINT(middle);
    }
  }
  closedir(dp);
  if (maxnum < 0) error->one(FLERR,"Found no restart file matching pattern");

  // create outfile with maxint substituted for "*"
  // use original infile, not pattern, since need to retain "%" in filename

  ptr = strchr(infile,'*');
  *ptr = '\0';
  sprintf(outfile,"%s" BIGINT_FORMAT "%s",infile,maxnum,ptr+1);
  *ptr = '*';

  // clean up

  delete [] dirname;
  delete [] filename;
  delete [] pattern;
  delete [] begin;
  delete [] middle;
  delete [] end;
}

/* ----------------------------------------------------------------------
   read header of restart file
------------------------------------------------------------------------- */

void ReadRestart::header()
{
  int px,py,pz;
  int xperiodic,yperiodic,zperiodic;
  int boundary[3][2];

  // read flags and values until flag = -1

  int flag = read_int();
  while (flag >= 0) {

    // check restart file version, warn if different

    if (flag == VERSION) {
      char *version = read_char();
      if (strcmp(version,universe->version) != 0 && me == 0) {
        error->warning(FLERR,
                       "Restart file version does not match LIGGGHTS version"); 
        if (screen) fprintf(screen,"   --> restart file = %s\n   --> LIGGGHTS = %s\n", 
                            version,universe->version);
      }
      delete [] version;

      // check lmptype.h sizes, error if different

    } else if (flag == SMALLINT) {
      int size = read_int();
      if (size != sizeof(smallint))
        error->all(FLERR,"Smallint setting in lmptype.h is not compatible");
    } else if (flag == TAGINT) {
      int size = read_int();
      if (size != sizeof(tagint))
        error->all(FLERR,"Tagint setting in lmptype.h is not compatible");
    } else if (flag == BIGINT) {
      int size = read_int();
      if (size != sizeof(bigint))
        error->all(FLERR,"Bigint setting in lmptype.h is not compatible");

      // reset unit_style only if different
      // so that timestep,neighbor-skin are not changed

    } else if (flag == UNITS) {
      char *style = read_char();
      if (strcmp(style,update->unit_style) != 0) update->set_units(style);
      delete [] style;

    } else if (flag == NTIMESTEP) {
      update->ntimestep = read_bigint();

      // set dimension from restart file

    } else if (flag == DIMENSION) {
      int dimension = read_int();
      domain->dimension = dimension;
      if (domain->dimension == 2 && domain->zperiodic == 0)
        error->all(FLERR,
                   "Cannot run 2d simulation with nonperiodic Z dimension");

      // read nprocs from restart file, warn if different

    } else if (flag == NPROCS) {
      nprocs_file = read_int();
      if (nprocs_file != comm->nprocs && me == 0)
        error->warning(FLERR,"Restart file used different # of processors");

      // don't set procgrid, warn if different

    } else if (flag == PROCGRID_0) {
      px = read_int();
    } else if (flag == PROCGRID_1) {
      py = read_int();
    } else if (flag == PROCGRID_2) {
      pz = read_int();
      if (comm->user_procgrid[0] != 0 &&
          (px != comm->user_procgrid[0] || py != comm->user_procgrid[1] ||
           pz != comm->user_procgrid[2]) && me == 0)
        error->warning(FLERR,"Restart file used different 3d processor grid");

    // don't set newton_pair, leave input script value unchanged
    // set newton_bond from restart file
    // warn if different and input script settings are not default

    } else if (flag == NEWTON_PAIR) {
      int newton_pair_file = read_int();
      if (force->newton_pair != 1) {
        if (newton_pair_file != force->newton_pair && me == 0)
          error->warning(FLERR,
                         "Restart file used different newton pair setting, "
                         "using input script value");
      }
    } else if (flag == NEWTON_BOND) {
      int newton_bond_file = read_int();
      if (force->newton_bond != 1) {
        if (newton_bond_file != force->newton_bond && me == 0)
          error->warning(FLERR,
                         "Restart file used different newton bond setting, "
                         "using restart file value");
      }
      force->newton_bond = newton_bond_file;
      if (force->newton_pair || force->newton_bond) force->newton = 1;
      else force->newton = 0;

      // set boundary settings from restart file
      // warn if different and input script settings are not default

    } else if (flag == XPERIODIC) {
      xperiodic = read_int();
    } else if (flag == YPERIODIC) {
      yperiodic = read_int();
    } else if (flag == ZPERIODIC) {
      zperiodic = read_int();
    } else if (flag == BOUNDARY_00) {
      boundary[0][0] = read_int();
    } else if (flag == BOUNDARY_01) {
      boundary[0][1] = read_int();
    } else if (flag == BOUNDARY_10) {
      boundary[1][0] = read_int();
    } else if (flag == BOUNDARY_11) {
      boundary[1][1] = read_int();
    } else if (flag == BOUNDARY_20) {
      boundary[2][0] = read_int();
    } else if (flag == BOUNDARY_21) {
      boundary[2][1] = read_int();

      if (domain->boundary[0][0] || domain->boundary[0][1] ||
          domain->boundary[1][0] || domain->boundary[1][1] ||
          domain->boundary[2][0] || domain->boundary[2][1]) {
        if (boundary[0][0] != domain->boundary[0][0] ||
            boundary[0][1] != domain->boundary[0][1] ||
            boundary[1][0] != domain->boundary[1][0] ||
            boundary[1][1] != domain->boundary[1][1] ||
            boundary[2][0] != domain->boundary[2][0] ||
            boundary[2][1] != domain->boundary[2][1]) {
          if (me == 0)
            error->warning(FLERR,
                           "Restart file used different boundary settings, "
                           "using restart file values");
        }
      }

      domain->boundary[0][0] = boundary[0][0];
      domain->boundary[0][1] = boundary[0][1];
      domain->boundary[1][0] = boundary[1][0];
      domain->boundary[1][1] = boundary[1][1];
      domain->boundary[2][0] = boundary[2][0];
      domain->boundary[2][1] = boundary[2][1];

      domain->periodicity[0] = domain->xperiodic = xperiodic;
      domain->periodicity[1] = domain->yperiodic = yperiodic;
      domain->periodicity[2] = domain->zperiodic = zperiodic;

      domain->nonperiodic = 0;
      if (xperiodic == 0 || yperiodic == 0 || zperiodic == 0) {
        domain->nonperiodic = 1;
        if (boundary[0][0] >= 2 || boundary[0][1] >= 2 ||
            boundary[1][0] >= 2 || boundary[1][1] >= 2 ||
            boundary[2][0] >= 2 || boundary[2][1] >= 2)
          domain->nonperiodic = 2;
      }

      // create new AtomVec class
      // if style = hybrid, read additional sub-class arguments

    } else if (flag == ATOM_STYLE) {
      char *style = read_char();

      int nwords = 0;
      char **words = NULL;

      if (strcmp(style,"hybrid") == 0) {
        nwords = read_int();
        words = new char*[nwords];
        for (int i = 0; i < nwords; i++) words[i] = read_char();
      }

      atom->create_avec(style,nwords,words);
      atom->avec->read_restart_settings(fp);

      for (int i = 0; i < nwords; i++) delete [] words[i];
      delete [] words;
      delete [] style;

    } else if (flag == NATOMS) {
      atom->natoms = read_bigint();
    } else if (flag == NTYPES) {
      atom->ntypes = read_int();
    } else if (flag == NBONDS) {
      atom->nbonds = read_bigint();
    } else if (flag == NBONDTYPES) {
      atom->nbondtypes = read_int();
    } else if (flag == BOND_PER_ATOM) {
      atom->bond_per_atom = read_int();
    } else if (flag == NANGLES) {
      atom->nangles = read_bigint();
    } else if (flag == NANGLETYPES) {
      atom->nangletypes = read_int();
    } else if (flag == ANGLE_PER_ATOM) {
      atom->angle_per_atom = read_int();
    } else if (flag == NDIHEDRALS) {
      atom->ndihedrals = read_bigint();
    } else if (flag == NDIHEDRALTYPES) {
      atom->ndihedraltypes = read_int();
    } else if (flag == DIHEDRAL_PER_ATOM) {
      atom->dihedral_per_atom = read_int();
    } else if (flag == NIMPROPERS) {
      atom->nimpropers = read_bigint();
    } else if (flag == NIMPROPERTYPES) {
      atom->nimpropertypes = read_int();
    } else if (flag == IMPROPER_PER_ATOM) {
      atom->improper_per_atom = read_int();

    } else if (flag == BOXLO_0) {
      domain->boxlo[0] = read_double();
    } else if (flag == BOXHI_0) {
      domain->boxhi[0] = read_double();
    } else if (flag == BOXLO_1) {
      domain->boxlo[1] = read_double();
    } else if (flag == BOXHI_1) {
      domain->boxhi[1] = read_double();
    } else if (flag == BOXLO_2) {
      domain->boxlo[2] = read_double();
    } else if (flag == BOXHI_2) {
      domain->boxhi[2] = read_double();

    } else if (flag == SPECIAL_LJ_1) {
      force->special_lj[1] = read_double();
    } else if (flag == SPECIAL_LJ_2) {
      force->special_lj[2] = read_double();
    } else if (flag == SPECIAL_LJ_3) {
      force->special_lj[3] = read_double();
    } else if (flag == SPECIAL_COUL_1) {
      force->special_coul[1] = read_double();
    } else if (flag == SPECIAL_COUL_2) {
      force->special_coul[2] = read_double();
    } else if (flag == SPECIAL_COUL_3) {
      force->special_coul[3] = read_double();

    } else if (flag == XY) {
      domain->triclinic = 1;
      domain->xy = read_double();
    } else if (flag == XZ) {
      domain->triclinic = 1;
      domain->xz = read_double();
    } else if (flag == YZ) {
      domain->triclinic = 1;
      domain->yz = read_double();

    } else error->all(FLERR,"Invalid flag in header section of restart file");

    flag = read_int();
  }
}

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

void ReadRestart::type_arrays()
{
  int flag = read_int();
  while (flag >= 0) {

    if (flag == MASS) {
      double *mass = new double[atom->ntypes+1];
      if (me == 0) nread_double(&mass[1],atom->ntypes,fp);
      MPI_Bcast(&mass[1],atom->ntypes,MPI_DOUBLE,0,world);
      atom->set_mass(mass);
      delete [] mass;

    } else error->all(FLERR,
                      "Invalid flag in type arrays section of restart file");

    flag = read_int();
  }
}

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

void ReadRestart::force_fields()
{
  int n;
  char *style;

  int flag = read_int();
  while (flag >= 0) {

    if (flag == PAIR) {
      n = read_int();
      style = new char[n];
      if (me == 0) nread_char(style,n,fp);
      MPI_Bcast(style,n,MPI_CHAR,0,world);

      force->create_pair_from_restart(fp, style);
      delete [] style;
      if (force->pair->restartinfo) force->pair->read_restart(fp);
      else {
        delete force->pair;
        force->pair = NULL;
      }

    } else if (flag == BOND) {
      n = read_int();
      style = new char[n];
      if (me == 0) nread_char(style,n,fp);
      MPI_Bcast(style,n,MPI_CHAR,0,world);

      force->create_bond(style);
      delete [] style;
      force->bond->read_restart(fp);

    } else if (flag == ANGLE) {
      n = read_int();
      style = new char[n];
      if (me == 0) nread_char(style,n,fp);
      MPI_Bcast(style,n,MPI_CHAR,0,world);

      force->create_angle(style);
      delete [] style;
      force->angle->read_restart(fp);

    } else if (flag == DIHEDRAL) {
      n = read_int();
      style = new char[n];
      if (me == 0) nread_char(style,n,fp);
      MPI_Bcast(style,n,MPI_CHAR,0,world);

      force->create_dihedral(style);
      delete [] style;
      force->dihedral->read_restart(fp);

    } else if (flag == IMPROPER) {
      n = read_int();
      style = new char[n];
      if (me == 0) nread_char(style,n,fp);
      MPI_Bcast(style,n,MPI_CHAR,0,world);

      force->create_improper(style);
      delete [] style;
      force->improper->read_restart(fp);

    } else error->all(FLERR,
                      "Invalid flag in force field section of restart file");

    flag = read_int();
  }
}

/* ----------------------------------------------------------------------
   read N ints from restart file
   do not bcast them, caller does that if required
------------------------------------------------------------------------- */

void ReadRestart::nread_int(int *buf, int n, FILE *fp)
{
  fread(buf,sizeof(int),n,fp);
  if (swapflag) {}
}

/* ----------------------------------------------------------------------
   read N doubles from restart file
   do not bcast them, caller does that if required
------------------------------------------------------------------------- */

void ReadRestart::nread_double(double *buf, int n, FILE *fp)
{
  fread(buf,sizeof(double),n,fp);
  if (swapflag) {}
}

/* ----------------------------------------------------------------------
   read N chars from restart file
   do not bcast them, caller does that if required
------------------------------------------------------------------------- */

void ReadRestart::nread_char(char *buf, int n, FILE *fp)
{
  fread(buf,sizeof(char),n,fp);
}

/* ----------------------------------------------------------------------
   read an int from restart file and bcast it
------------------------------------------------------------------------- */

int ReadRestart::read_int()
{
  int value;
  if (me == 0) {
    fread(&value,sizeof(int),1,fp);
    if (swapflag) {}
  }
  MPI_Bcast(&value,1,MPI_INT,0,world);
  return value;
}

/* ----------------------------------------------------------------------
   read a double from restart file and bcast it
------------------------------------------------------------------------- */

double ReadRestart::read_double()
{
  double value;
  if (me == 0) {
    fread(&value,sizeof(double),1,fp);
    if (swapflag) {}
  }
  MPI_Bcast(&value,1,MPI_DOUBLE,0,world);
  return value;
}

/* ----------------------------------------------------------------------
   read a char str from restart file and bcast it
   str is allocated here, ptr is returned, caller must deallocate
------------------------------------------------------------------------- */

char *ReadRestart::read_char()
{
  int n;
  if (me == 0) {
    fread(&n,sizeof(int),1,fp);
    if (swapflag) {}
  }
  MPI_Bcast(&n,1,MPI_INT,0,world);
  char *value = new char[n];
  if (me == 0) {
    fread(value,sizeof(char),n,fp);
    if (swapflag) {}
  }
  MPI_Bcast(value,n,MPI_CHAR,0,world);
  return value;
}

/* ----------------------------------------------------------------------
   read a bigint from restart file and bcast it
------------------------------------------------------------------------- */

bigint ReadRestart::read_bigint()
{
  bigint value;
  if (me == 0) {
    fread(&value,sizeof(bigint),1,fp);
    if (swapflag) {}
  }
  MPI_Bcast(&value,1,MPI_LMP_BIGINT,0,world);
  return value;
}

/* ----------------------------------------------------------------------
   auto-detect if restart file needs to be byte-swapped on this platform
   return 0 if not, 1 if it does
   re-open file with fp after checking first few bytes
   read a bigint from restart file and bcast it
   NOTE: not yet fully implemented, ditto for swapflag logic
------------------------------------------------------------------------- */

int ReadRestart::autodetect(FILE **pfp, char *file)
{
  FILE *fp = *pfp;

  // read, check, set return flag

  int flag = 0;

  // reset file pointer

  fclose(fp);
  fp = fopen(file,"rb");
  *pfp = fp;

  return flag;
}
