towers_of_hanoi.rb

class TowersOfHanoi
  attr_reader :towers

  def initialize
    @towers = [[4, 3, 2, 1], [], []]
  end

  def play
    from = ""
    while !win?
      puts "Select tower to move disc from [1 - 4]: "
      from = gets.chomp.to_i
      if !valid?(from)
        puts "Move invalid. Please select again."
        play
      end
      puts "Select tower to move disc to [1 - 4]: "
      to = gets.chomp.to_i
      if !valid?(from, to)
        puts "Move invalid. Please select again."
        play
      else
        make_move(from, to)
      end
    end
  end

  def make_move(from, to)
    @towers[to - 1] << @towers[from - 1].pop
    p @towers
  end

  def win?
    if @towers[0].empty?
      if towers[1].empty? || towers[2].empty?
        puts "YOU WON!"
        return true
      end
    end
    return false
  end

  def valid?(from, to = nil)
    if to == nil
      @towers[from - 1].length > 0
    else
      return false if from == to
      @towers[to - 1].empty? || @towers[from - 1].last < @towers[to - 1].last
    end
  end
end

new_game = TowersOfHanoi.new
new_game.play