/***************************************************************************
 *cr
 *cr            (C) Copyright 1995-2002 The Board of Trustees of the
 *cr                        University of Illinois
 *cr                         All Rights Reserved
 *cr
 ***************************************************************************/

/***************************************************************************
 * RCS INFORMATION:
 *
 *      $RCSfile: crdplugin.c,v $
 *      $Author: johns $       $Locker:  $             $State: Exp $
 *      $Revision: 1.7 $       $Date: 2002/05/31 19:16:55 $
 *
 ***************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "molfile_plugin.h"

typedef struct {
  FILE *file;
  int has_box;
  int numatoms;
} crddata;
  
static void *open_crd_read(const char *filename, const char *filetype, 
  molfile_header_t *header) {
 
  FILE *fd;
  crddata *data;
 
  fd = fopen(filename, "rb");
  if (!fd) return NULL;
  
  /* first line is title, so skip past it */
  while (getc(fd) != 10);
  /* 
   * CRD's don't store the number of atoms in the timestep, so we assume that
   * the application will determine this for us.  Also don't know how many
   * frames there are.
   */
  data = (crddata *)malloc(sizeof(crddata));
  data->file = fd;
  header->numatoms = -1;
  header->numsteps = -1;
  /* filetype "crd" has no box; filetype "crdbox" does. */
  data->has_box = strcmp(filetype, "crd"); 
  return data;
}

/*
 * CRD files with box info are indistinguishable from regular CRD's.  We
 * regard CRD's with box info as a different file format.
 * molfile_timestep_t doesn't have box info yet.  Also, CRD's don't tell
 * how many atoms there are in each frame.  We therefore rely on the
 * numatoms field in the molfile_timestep_t parameter.
 */
static int read_crd_timestep(void *mydata, molfile_timestep_t *ts) {

  crddata *crd = (crddata *)mydata;
  int i, j;
  float x, y, z;
  float a, b, c;

  for (i=0; i<ts->numatoms; i++) {
    j = fscanf(crd->file, "%f %f %f", &x, &y, &z);
    if (j == EOF) {
      return -1;
    } else if (j <= 0) {
      fprintf(stderr, "Problem reading CRD file\n");
      return 1;
    }
    ts->coords[3*i] = x;
    ts->coords[3*i+1] = y;
    ts->coords[3*i+2] = z;
    if (crd->has_box) {
      /* Scan through box info without reading it. */
      j = fscanf (crd->file, "%f %f %f %f %f %f", &a, &b, &c, &x, &y, &z);
      if (j == EOF) {
        printf("EOF in box\n");
        return -1;
      } else if (j <= 0) {
        printf("Problem reading box part of CRD file, scanf returned %d\n",j);
        return -1;
      }
    }
  }
  return 0;
}
    
static void close_crd_read(void *mydata) {
  crddata *crd = (crddata *)mydata;
  fclose(crd->file);
  free(crd);
}

static void *open_crd_write(const char *path, const char *filetype,
                            const molfile_header_t *header) {
  crddata *crd;
  FILE *fd;

  fd = fopen(path, "wb");
  if (!fd) {
    fprintf(stderr, "Could not open file %s for writing\n", path);
    return NULL;
  }
  fprintf(fd, "TITLE : Created by VMD with %d atoms, %d steps\n", 
    header->numatoms, header->numsteps);
  
  crd = (crddata *)malloc(sizeof(crddata));
  crd->file = fd;
  crd->numatoms = header->numatoms;
  crd->has_box = strcmp(filetype, "crd"); 
  return crd;
}    
  
static int write_crd_timestep(void *v, const molfile_timestep_t *ts) {

  crddata *crd = (crddata *)v;
  int i;
  const int ndata = crd->numatoms * 3;
  for (i=0; i<ndata; i++) {
    fprintf(crd->file, "%8.3f", ts->coords[i]);
    if (i % 10 == 0) fprintf(crd->file, "\n"); 
  }
  if (crd->has_box) {
    fprintf (crd->file, "\n0.000 0.000 0.000\n");
  }
  return 0;
}

static void close_crd_write(void *v) {
  crddata *crd = (crddata *)v;
  fclose(crd->file);
  free(crd);
}

/* registration stuff */
static molfile_api crdapi = {
    "crd",
    open_crd_read,
    0,
    read_crd_timestep,
    close_crd_read,
    open_crd_write,
    0,
    write_crd_timestep,
    close_crd_write
};

int VMDPLUGIN_register(void *v, vmdplugin_register_cb cb) {
  vmdplugin_t plugin = {
    MOLFILE_PLUGIN_TYPE,          /* type */
    "",                           /* name */
    "Justin Gullingsrud",         /* author */
    0,                                            /* major version */
    1,                                            /* minor version */
    1,                                            /* is reentrant */
    &crdapi
  };
  plugin.name = "crd";
  (*cb)(v, &plugin);
  plugin.name = "crdbox";
  (*cb)(v, &plugin);
  return 0;
}