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

#define MAX 256

void readGray ( int A[][MAX], int *ht, int *wd, char *fname )
{
   FILE *fp;
   char tmp[100];
   int lev, i, j;

   fp = (FILE *)fopen(fname,"r");
   if (fp == NULL) {
      fprintf(stderr,"Error opening input file...\n");
      exit(1);
   }
   fscanf(fp,"%s",tmp);
   fscanf(fp,"%d%d%d",wd,ht,&lev);
   for (i=0; i<*ht; ++i) for (j=0; j<*wd; ++j) fscanf(fp,"%d",&A[i][j]);
   fclose(fp);
   printf("%d x %d image read from \"%s\".\n", *wd, *ht, fname);
}

void readColor ( int R[][MAX], int G[][MAX],
                 int B[][MAX], int *ht, int *wd, char *fname )
{
   FILE *fp;
   char tmp[100];
   int lev, i, j;

   fp = (FILE *)fopen(fname,"r");
   if (fp == NULL) {
      fprintf(stderr,"Error opening input file...\n");
      exit(1);
   }
   fscanf(fp,"%s",tmp);
   fscanf(fp,"%d%d%d",wd,ht,&lev);
   for (i=0; i<*ht; ++i) for (j=0; j<*wd; ++j)
      fscanf(fp,"%d%d%d",&R[i][j], &G[i][j], &B[i][j]);
   fclose(fp);
   printf("%d x %d image read from \"%s\".\n", *wd, *ht, fname);
}

void writeGray ( int A[][MAX], int ht, int wd, char *fname )
{
   FILE *fp;
   int i, j;

   fp = (FILE *)fopen(fname,"w");
   if (fp == NULL) {
      fprintf(stderr,"Error opening output file...\n");
      exit(1);
   }
   fprintf(fp,"P2\n%d %d\n255\n",wd,ht);
   for (i=0; i<ht; ++i) for (j=0; j<wd; ++j) fprintf(fp,"%d\n",A[i][j]);
   fclose(fp);
   printf("%d x %d image saved as \"%s\".\n", wd, ht, fname);
}

void writeColor ( int R[][MAX], int G[][MAX], int B[][MAX], int ht, int wd, char *fname )
{
   FILE *fp;
   int i, j;

   fp = (FILE *)fopen(fname,"w");
   if (fp == NULL) {
      fprintf(stderr,"Error opening output file...\n");
      exit(1);
   }
   fprintf(fp,"P3\n%d %d\n255\n",wd,ht);
   for (i=0; i<ht; ++i) for (j=0; j<wd; ++j)
      fprintf(fp,"%d %d %d\n",R[i][j],G[i][j],B[i][j]);
   fclose(fp);
   printf("%d x %d image saved as \"%s\".\n", wd, ht, fname);
}

void blurComp ( int D[][MAX], int D_[][MAX], int ht, int wd, int k )
{
   int npxl, i, j, i_, j_;

   for (i=0; i<ht; ++i) for (j=0; j<wd; ++j) {
      npxl = 0; D_[i][j] = 0;
      for (i_=i-k; i_<=i+k; ++i_) for (j_=j-k; j_<=j+k; ++j_) {
         if ((i_>=0) && (i_<ht) && (j_>=0) && (j_<wd)) {
            ++npxl; D_[i][j] += D[i_][j_];
         }
      }
      D_[i][j] /= npxl;
   }
}

int main ()
{
   int A[MAX][MAX], B[MAX][MAX], C[MAX][MAX],
       A_[MAX][MAX], B_[MAX][MAX], C_[MAX][MAX];
   int ht, wd;

   /*** Part 1 ***/
   readGray(A,&ht,&wd,"light.pnm");
   blurComp(A,A_,ht,wd,3);
   writeGray(A_,ht,wd,"light-blurred.pnm");

   /*** Part 2 ***/
   readColor(A,B,C,&ht,&wd,"duck.pnm");
   blurComp(A,A_,ht,wd,2);
   blurComp(B,B_,ht,wd,2);
   blurComp(C,C_,ht,wd,2);
   writeColor(A_,B_,C_,ht,wd,"duck-blurred.pnm");

   exit(0);
}