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

typedef unsigned char uchar;

uchar Ri[1080][1920], Gi[1080][1920], Bi[1080][1920];
uchar Ro[1080][1920], Go[1080][1920], Bo[1080][1920];

void readfile ()
{
   int i, j, r, g, b;
   FILE *fp;

   fp = (FILE *)fopen("original.ppm", "r");
   while (fgetc(fp) != '\n');
   while (fgetc(fp) != '\n');
   while (fgetc(fp) != '\n');

   for (i=0; i<1080; ++i) {
      for (j=0; j<1920; ++j) {
         fscanf(fp, "%d%d%d", &r, &g, &b);
         Ri[i][j] = (uchar)r;
         Gi[i][j] = (uchar)g;
         Bi[i][j] = (uchar)b;
      }
   }
   fclose(fp);
}

void blur ( int k )
{
   int i, j, rs, re, cs, ce, rd, cd, u, v, r, g, b, c;

   for (i=0; i<1080; ++i) {
      for (j=0; j<1920; ++j) {
         rs = i - k; if (rs < 0) rs = 0;
         re = i + k; if (re >= 1080) re = 1079;
         cs = j - k; if (cs < 0) cs = 0;
         ce = j + k; if (ce >= 1920) ce = 1919;
         r = g = b = c = 0;
         for (u=rs; u<=re; ++u) {
            rd = (u - i) * (u - i);
            for (v=cs; v<=ce; ++v) {
               cd = (v - j) * (v - j);
               if (rd + cd <= k * k) {
                  ++c;
                  r += Ri[u][v];
                  g += Gi[u][v];
                  b += Bi[u][v];
               }
            }
         }
         Ro[i][j] = r / c;
         Go[i][j] = g / c;
         Bo[i][j] = b / c;
      }
   }
}

void writefile ()
{
   int i, j;
   FILE *fp;

   fp = (FILE *)fopen("blurred.ppm", "w");
   fprintf(fp, "P3\n1920 1080\n255\n");
   for (i=0; i<1080; ++i) {
      for (j=0; j<1920; ++j) {
         fprintf(fp, "%d %d %d\n", (int)Ro[i][j], (int)Go[i][j], (int)Bo[i][j]);
      }
   }
   fclose(fp);
}

int main ( int argc, char *argv[] )
{
   int k = 5;
   if (argc > 1) k = atoi(argv[1]);

   readfile();   printf("Input file read\n");
   blur(k);      printf("Blurring done\n");
   writefile();  printf("Output file written\n");

   exit(0);
}