/*
Jason Lawrence
Princeton University

pfm.cc

File I/O for images stored in PFM format.
*/

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

#include "pfm.h"

inline void check_string(char *buf, const char *tag)
{
  if (strncmp(buf+2,tag,strlen(tag)==0)) {
    fprintf(stderr, "Invalid header or file not valid \"gantry\" PFM image.\n");
    fprintf(stderr, "Failed at tag: [%s]\n", tag);
    exit(1);
  }
}

inline void get_string(FILE *in, const char *tag, char *value)
{
  static char buf[1024];

  fgets(buf,1024,in);buf[1023]=0;
  check_string(buf,tag);

  // Trim trailing newline
  buf[strlen(buf)-1]=0;
  char *needle = strstr(buf,":");
  if (!needle) {
    fprintf(stderr, "Failed to parse [%s]\n", buf);
    exit(1);
  }
  // Copy past comment field
  strcpy(value,needle+1);
}

inline void get_double(FILE *in, const char *tag, double &value)
{
  static char buf[1024];

  fgets(buf,1024,in);buf[1023]=0;
  check_string(buf,tag);

  // Trim trailing newline
  buf[strlen(buf)-1]=0;
  char *needle = strstr(buf,":");
  if (!needle) {
    fprintf(stderr, "Failed to parse [%s]\n", buf);
    exit(1);
  }
  // Copy past comment field
  value = atof(needle+1);
}

inline void get_int(FILE *in, const char *tag, int &value)
{
  static char buf[1024];

  fgets(buf,1024,in);buf[1023]=0;
  check_string(buf,tag);

  // Trim trailing newline
  buf[strlen(buf)-1]=0;
  char *needle = strstr(buf,":");
  if (!needle) {
    fprintf(stderr, "Failed while parsing [%s]\n", buf);
    exit(1);
  }
  // Copy past comment field
  value = atoi(needle+1);
}

void read_header (FILE *in, gantry_img_header_t &header)
{
  // Blank header
  bzero(&header,sizeof(header));

  // Parse PFM header
  static char buf[1024];
  fgets(buf, 1024, in);
  fgets(buf, 1024, in);
  sscanf(buf, "%d %d", &header.width, &header.height);
  if (header.width < 0 || header.height < 0) {
    fprintf(stderr, "Invalid header or file not valid \"Cornell gantry\" PFM image.\n");
    exit(1);
  }

  get_string(in,"COLORBAL",header.colorbal);
  get_string(in,"READOUT",header.readout);
  get_string(in,"COMMENT",header.comment);
  get_string(in,"DATE",header.date);
  get_string(in,"GAIN",header.gain);
  get_string(in,"OFFSET",header.offset);
  get_string(in,"EXPOSURES",header.exps);
  get_string(in,"COLOR",header.color);
  get_int   (in,"WIDTH",header.orig_width);
  get_int   (in,"HEIGHT",header.orig_height);
  get_int   (in,"BANDS",header.bands);
  get_double(in,"LIGHT",header.light);
  get_double(in,"BASE",header.base);
  get_double(in,"OBJECT",header.obj);
  get_double(in,"CAMERA",header.cam);
  get_double(in,"THETAV",header.thetav);
  get_double(in,"PHIV",header.phiv);
  get_double(in,"THETAL",header.thetal);
  get_double(in,"PHIL",header.phil);
  get_double(in,"THETAH",header.thetah);

  get_double(in,"OFFX",header.offx);
  get_double(in,"OFFY",header.offy);

  get_double(in,"VX",header.vx);
  get_double(in,"VY",header.vy);
  get_double(in,"VZ",header.vz);

  get_double(in,"LX",header.lx);
  get_double(in,"LY",header.ly);
  get_double(in,"LZ",header.lz);

  fgets(buf, 1024, in);
  if (buf[0] == '#') {
    fprintf(stderr, "Invalid header or file not valid \"Cornell gantry\" PFM image.\n");
    fprintf(stderr, "Failed after last tag.\n");
    exit(1);
  }  
}

float * read_pfm (char *fname, gantry_img_header_t &header)
{
  // Open image file
  FILE *in = fopen(fname, "rb");
  if (!in) {
    fprintf(stderr, "Failed to open file [%s].\n",fname);
    return NULL;
  }

  read_header(in,header);
  
  float *img = new float[header.width*header.height*3];

  // Read pixel data
  if (fread(img, sizeof(float), 3*header.width*header.height, in) != 3*header.width*header.height) {
    fprintf(stderr, "Unexpected EOF while reading image data.\n");
    return NULL;
  }
  
  fclose(in);
  
  return img;
}

bool read_pfm (char *fname, gantry_img_header_t &header, float *img)
{
  // Open image file
  FILE *in = fopen(fname, "rb");
  if (!in) {
    fprintf(stderr, "Failed to open file [%s].\n",fname);
    return false;
  }

  read_header(in,header);
  
  // Read pixel data
  if (fread(img, sizeof(float), 3*header.width*header.height, in) != 3*header.width*header.height) {
    fprintf(stderr, "Unexpected EOF while reading image data.\n");
    return false;
  }
  
  fclose(in);
  
  return true;
}