#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "ppm.h"
// based on code from http://rosettacode.org/wiki/Bitmap/Read_a_PPM_file#C

#define BMAX	256
ppm_t * 
ppmread (char *filename)
{

  unsigned char buf[BMAX], *t;
  FILE *fp = fopen (filename, "r");
  char c;
  int r;
  int pixels;
  int i, j, p;
  ppm_t *image;

  if (fp == NULL) return NULL;

  t = (unsigned char *)fgets ((char *)buf, BMAX, fp);
  if ((t == NULL) || (strncmp ((const char *)buf, "P3\n", 3) != 0))
  {
    fprintf (stderr, "file does not start with 'P3\\n'\n");
    return NULL;
  }
  
  while (1) {
    t = (unsigned char *) fgets ((char *)buf, BMAX, fp);
    if (*t != '#') break;
  }
  image = (ppm_t *) malloc (sizeof (ppm_t));
  if (image == NULL) return NULL;

  image->x = 0;
  image->y = 0;
  image->d = 0;

  r = sscanf ((const char *)buf, "%u %u", &image->x, &image->y);
  if ( r < 2 ) {free (image); return NULL; }
 
  r = fscanf (fp, "%u", &image->d);
  if ( (r < 1) || ( image->d != 255 ) ) { free (image); return NULL; }
  pixels = (image->x) * (image->y) * 3;
  image->rgb =  (unsigned char *) malloc (pixels);
  if (image->rgb == NULL) { free (image); return NULL; }

  fprintf (stderr, "image '%s' %3d x %3d , depth=%3d\n", filename, image->x, image->y, image->d);

  if (image->rgb == NULL) return NULL;
  t = image->rgb;
  for (i = 0; i < image->x; i++)
    for (j = 0; j < image->y; j++)
      for (p = 0; p < 3; p++)
      {
         r = fscanf (fp, "%u", t);
         // fprintf (stderr, "pixel[%3d][%3d]=%3u\n", i, j, *t);
         if (r != 1) return NULL;
         t++;
      }
 return image;
}

int 
ppmwrite (char *filename, ppm_t *image)
{

  FILE *fp = fopen (filename, "w");
  int i, j, p;
  unsigned char *t;

  fprintf (fp, "P3\n%u %u\n%u\n", image->x, image->y, image->d);
  t = image->rgb;
  for (i = 0; i < image->x; i++)
  {
    for (j = 0; j < image->y; j++)
    {
      for (p = 0; p < 3; p++)
      {
         fprintf (fp, "%u ", *t);
         t++;
      }
      fprintf (fp, " ");
    }
    fprintf (fp, "\n");
  }
}

void
ppmfree (ppm_t *image)
{
  free (image->rgb);
  free (image);
}

ppm_t *
ppmalloc (int x, int y, int d)
{

  ppm_t *image = (ppm_t *) malloc (sizeof (ppm_t));
  if (image == NULL) return NULL;
  image->x = x;
  image->y = y;
  image->d = d;
  image->rgb = (unsigned char *) malloc (x * y * 3);
  if (image->rgb == NULL) 
  {
    free (image);
    return NULL;
  }
  return image;
}
/*
int
main (int argc, char *argv[])
{

  unsigned int x, y, d;
  char *fn = "Untitled.ppm";
  ppm_t *image;
  image = ppmread (fn);

  ppmwrite ("out.ppm", image);

 return;
}
*/