#!/usr/bin/env ruby
# -*- ruby -*-
# perlLife.pl - Conway's Game of Life
# Copyright (C) YAMAMIYA Takasi

CLEAR = "\33c"

class LifeMap

  def initialize(x, y)
    # @board[x][y] = cell
    @board = newBoard(x, y)
  end

  def newBoard(x, y)
    board = Array.new(x)
    board.map! do |row|
      Array.new(y)
    end
    board
  end
  private :newBoard

  def width() @board.size end
  def height() @board[0].size end

  def random
    (0 ... width).each do |x|
      (0 ... height).each do |y|
        @board[x][y] = rand < 0.5 ? true : false
      end
    end
  end
  
  def show
    print CLEAR
    (0 ... width).each do |x|
      (0 ... height).each do |y|
        print @board[x][y] ? "O " : "  "
      end
      print "\n"
    end
  end

  def step
    newBoard = newBoard(width, height)

    (0 ... width).each do |x|
      (0 ... height).each do |y|
        newBoard[x][y] = nextWhen(@board[x][y], numAt(x, y))
      end
    end
    @board = newBoard
  end
  
  def numAt(x, y)
    sum = 0
    [
      [x - 1, y - 1], [x - 1, y    ], [x - 1, y + 1],
      [x    , y - 1],                 [x    , y + 1],
      [x + 1, y - 1], [x + 1, y    ], [x + 1, y + 1]
    ].each do |_x, _y|
      sum += 1 if (0 <= _x and _x < width and
                   0 <= _y and _y < height and
                   @board[_x][_y]) 
    end
    sum
  end
  private :numAt

  def nextWhen(cell, num)
    if (cell) then
      return ([false, false, true, true, false, false, false, false, false, false, false, false][num])
    else
      return ([false, false, false, true, false, false, false, false, false, false, false, false][num])
    end
  end
  private :nextWhen

end

# main
while "forever" do
  board = LifeMap.new(20,20)
  board.random
  (1 .. 50).each do
    board.step
    board.show
    sleep 0.2
  end
end