#include "library.h"

const int size = 60;          // the grid has 60 x 60 squares
bool alive[size][size];
const int border = 50;        // 50 pixel empty border around the edge
const int cell_size = 10;     // each square is 10 pixels wide
const int grid_size = 2*border + size*cell_size;

void draw()
{ int line = 0;
  fill_rectangle(0, 0, grid_size, grid_size, color::white);
  while (line <= size)
  { move_to(border + line * cell_size, border);
    draw_to(border + line * cell_size, border + size * cell_size);
    move_to(border, border + line * cell_size);
    draw_to(border + size * cell_size, border + line * cell_size);
    line = line + 1; }
  int i = 0;
  while (i < size)
  { int j = 0;
    while (j < size)
    { if (alive[i][j])
      { const int x = border + j * cell_size;
        const int y = border + i * cell_size;
        fill_rectangle(x, y, cell_size, cell_size, color::red); }
      j = j + 1; }
    i = i + 1; } }

void init()
{ int i = 0;
  while (i < size)
  { int j = 0;
    while (j < size)
    { alive[i][j] = false;
      j = j + 1; }
    i = i + 1; }
  while (true)
  { draw();
    wait_for_mouse_click();
    const int x = get_click_x();
    const int y = get_click_y();
    if (x < border)                // click in the left border to finish
      break;
    const int cellx = (x - border) / cell_size;
    const int celly = (y - border) / cell_size;
    alive[celly][cellx] = ! alive[celly][cellx]; } }

bool safelook(int a, int b)
{ if (a<0 || b<0 || a>=size || b>=size)
    return false;
  return alive[a][b]; }

int count_neighbours(int i, int j)
{ int count = 0;
  int a = -1;
  while (a <= 1)
  { int b = -1;
    while (b <= 1)
    { if (a!=0 || b!=0)
      { if (safelook(i+a, j+b))
          count = count + 1; }
      b = b + 1; }
    a = a + 1; }
  return count; }

void step()            // This isn't correct yet. The fate of every cell depends
{ int i = 0;           // on the initial conditions. Neighbours dying or being born
  while (i < size)     // must have no effect until the next cycle.
  { int j = 0;
    while (j < size)
    { const int neigh = count_neighbours(i, j);
                // the rules: for each cell count how many of its
                // eight neighbours are alive:
                //   less than 2, it dies of loneliness
                //   more than 3, it dies from overcrowding
                //   exactly 2, no change
                //   exactly 3, it comes to life
      if (neigh < 2 || neigh > 3)
        alive[i][j] = false;
      else if (neigh == 3)
        alive[i][j] = true;
      j = j + 1; }
    i = i + 1; } }

void main()
{ make_window(grid_size, grid_size);
  init();
  step();
  draw(); }