// 2D and image functions
//
#include "ppm.h"

void row_zero( unsigned char z[], int n) { // zero out a 1D array
  for( int k = 0; k < n; ++k) z[k] = 0;
}

// int x[][] -- won't work, need to know the number of columns

void zero( unsigned char **x, int rows, int cols ) { // zero out a 2D array
  // for( int i = 0; i < rows; ++i) for( int j = 0; j < cols; ++j) {
  //   x[i][j] = 0;
  // }
  for( int i = 0; i < rows; ++i) row_zero( x[i], cols);
}

void gray( ppm a) { // change image to grayscale
  for( int i = 0; i < a.rows; ++i) for( int j = 0; j < a.cols; ++j) {
    // a.r[i][j] = 0; // remove red
    int avg = (a.r[i][j] + a.g[i][j] + a.b[i][j])/3;
    // if( avg < 50) avg = 0; else avg = 255; // black and white
    a.r[i][j] = a.g[i][j] = a.b[i][j] = avg; // grayscale
  }
}

int main( void)
{
  ppm a = ppm_read(); // a.rows, a.cols, a.r, a.g, a.b
  // gray(a);
  zero( a.g, a.rows, a.cols);
  ppm_write( a);
  return 0;
}