# https://gist.github.com/bennuttall/6952575
# modified a lot

import random, simplegui

# cells
width = 15
height = 15
scale = 9  # pixels per cell

neighbour_cells = [(-1, -1), (-1, 0), (-1, 1), (0, -1),
                   (0, 1), (1, -1), (1, 0), (1, 1)]

def evolve_cell(alive, neighbours):
    return neighbours == 3 or (alive and neighbours == 2)

def count_neighbours(grid, x, y):
    count = 0
    for ox,oy in neighbour_cells:
      dx = x + ox
      dy = y + oy
      # no wrap
      if dx >= 0 and dx < width and dy >= 0 and dy < height:
        count += grid[dx][dy]
    return count

def make_random_grid(x, y):
        grid = []
        for r in range(x):
            row = []
            for c in range(y):
                row.append(random.randint(0,1))
            grid.append(row)
        return grid

# use the old grid as the new one
def evolve(grid, new_grid):
    for r in range(width):
        for c in range(height):
            cell = grid[r][c]
            neighbours = count_neighbours(grid, r, c)
            new_grid[r][c] = 1 if evolve_cell(cell, neighbours) else 0
    # store the outgoing world for next time
    return (new_grid, grid)

# Handler to draw on canvas
def draw(canvas):
  global world, oldworld
  for x in range(width):
    for y in range(height):
      alive = world[x][y]
      col = 'black' if alive else 'white'
      try:
        # canvas.draw_circle(center_point, radius, line_width, line_color, fill_color)
        canvas.draw_circle([x * scale + scale//2, y * scale + scale//2], scale//2, 1, '#ccc', col)
      except Exception as e:
        # I don't get this!  Says that col has no value
        col = 'red'
        canvas.draw_circle([x * scale + scale//2, y * scale + scale//2], scale//2, 1, col, col)
  # store the outgoing world for next time
  world, oldworld = evolve(world, oldworld)

def init():
  global world, oldworld
  # make two arrays which we use alternately
  world = make_random_grid(width, height)
  oldworld = make_random_grid(width, height)

def main():
  # Create a frame and assign callbacks to event handlers
  frame = simplegui.create_frame("Conway Life", width * scale, height * scale)
  frame.set_canvas_background('white')
  frame.set_draw_handler(draw)

  init()

  # Start the frame animation
  frame.start()

if __name__ == '__main__':
    main()