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


#include "pnm_image.h"

#define NEWA(type,n) (type*)malloc(sizeof(type)*(n))
#define NEW(type) NEWA(type,1)

image_t *image_new(int width, int height) {
  image_t *im=NEW(image_t);
  im->width=im->stride=width;
  im->height=height;
  int wh=width*height;
  im->data=NEWA(float,wh);
  return im;
}

image_t *image_cpy(image_t *src) {
  image_t *im=image_new(src->width,src->height); 
  memcpy(im->data,src->data,sizeof(*(src->data))*src->width*src->height);
  return im;
}

void image_delete(image_t *im) {
  free(im->data);
  free(im);
}


color_image_t *color_image_new(int width, int height) {
  color_image_t *im=NEW(color_image_t);
  im->width=width;
  im->height=height;
  int wh=width*height;
  im->c1=NEWA(float,wh);
  im->c2=NEWA(float,wh);
  im->c3=NEWA(float,wh);
  return im;
}

color_image_t *color_image_cpy(color_image_t *src) {
  color_image_t *im=color_image_new(src->width,src->height); 
  memcpy(im->c1,src->c1,sizeof(*(src->c1))*src->width*src->height);
  memcpy(im->c2,src->c2,sizeof(*(src->c1))*src->width*src->height);
  memcpy(im->c3,src->c3,sizeof(*(src->c1))*src->width*src->height);
  return im;
}

void color_image_delete(color_image_t *im) {
  free(im->c1);
  free(im->c2);
  free(im->c3);
  free(im);
}




color_image_t *load_ppm(const char *fname) {
  FILE *f=fopen(fname,"r");
  if(!f) {
    perror("could not open infile");
    exit(1);
  }
  int px,width,height,maxval;
  if(fscanf(f,"P%d %d %d %d",&px,&width,&height,&maxval)!=4 || 
     maxval!=255 || (px!=6 && px!=5)) {
    fprintf(stderr,"Error: input not a raw PGM/PPM with maxval 255\n");
    exit(1);    
  }
  fgetc(f); /* eat the newline */
  color_image_t *im=color_image_new(width,height);

  int i;
  for(i=0;i<width*height;i++) {
    im->c1[i]=fgetc(f);
    if(px==6) {
      im->c2[i]=fgetc(f);
      im->c3[i]=fgetc(f);    
    } else {
      im->c2[i]=im->c1[i];
      im->c3[i]=im->c1[i];   
    }
  }
  
  fclose(f);
  return im;
}

image_t *color_image_channel(const color_image_t *cim, ColorChannel channel) {
  image_t *ret = image_new(cim->width, cim->height); 
  int i; 
  
  float *src = 
    channel == CHANNEL_R ? cim->c1 : 
    channel == CHANNEL_G ? cim->c2 : 
    channel == CHANNEL_B ? cim->c3 : 
    NULL; 
  assert(src || !"unknown channel");   

  memcpy(ret->data, src, sizeof(float) * cim->width * cim->height); 

  return ret; 
}