towers

towers.rb

# Towers of Hanoi
#
# Write a Towers of Hanoi game:
# http://en.wikipedia.org/wiki/Towers_of_hanoi
#
# In a class `TowersOfHanoi`, keep a `towers` instance variable that is an array
# of three arrays. Each subarray should represent a tower. Each tower should
# store integers representing the size of its discs. Expose this instance
# variable with an `attr_reader`.
#
# You'll want a `#play` method. In a loop, prompt the user using puts. Ask what
# pile to select a disc from. The pile should be the index of a tower in your
# `@towers` array. Use gets
# (http://andreacfm.com/2011/06/11/learning-ruby-gets-and-chomp/) to get an
# answer. Similarly, find out which pile the user wants to move the disc to.
# Next, you'll want to do different things depending on whether or not the move
# is valid. Finally, if they have succeeded in moving all of the discs to
# another pile, they win! The loop should end.
#
# You'll want a `TowersOfHanoi#render` method. Don't spend too much time on
# this, just get it playable.
#
# Think about what other helper methods you might want. Here's a list of all the
# instance methods I had in my TowersOfHanoi class:
# * initialize
# * play
# * render
# * won?
# * valid_move?(from_tower, to_tower)
# * move(from_tower, to_tower)
#
# Make sure that the game works in the console. There are also some specs to
# keep you on the right track:
#
# ```bash
# bundle exec rspec spec/towers_of_hanoi_spec.rb
# ```

#
# Make sure to run bundle install first! The specs assume you've implemented the
# methods named above.

class TowersOfHanoi
  attr_reader :towers

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

  def play
    select_from_tower
    select_to_tower
    if valid_move?
      move
    else
      puts "Please select another move."
      return play
    end
    if won?
      puts "congratulations, you won!"
    else
      return move
    end
  end

  def select_from_tower
    puts "Please select a tower to choose a disc from - select either 1, 2 or 3."
    from_tower = gets.chomp.to_i
    if from_tower.from_tower_valid?
      return from_tower
    else 
      puts "Please select a valid tower."
    end
  end

  def from_tower_valid(from_tower)
    (@towers[from_tower].length != 0)  && ([1,2,3].include?(@towers[from_tower]))
  end

  def select_to_tower
    until [0,1,2].include?(to_tower)
      puts "Please select a tower to move to - select either 1, 2 or 3."
      to_tower = gets.chomp
    end
  end

  def move(from_tower, to_tower)
    @towers[to_tower] << @towers[from_tower].pop
  end

  def valid_move?(from_tower, to_tower)
    if @towers[from_tower].length == 0
      return false
    elsif @towers[to_tower].length == 0
      return true
    end
    (@towers[to_tower].last > @towers[from_tower].last) || @towers[to_tower].length == 0
  end

  def won?
    (@towers[0].length == 0 && @towers[1].length == 0) || (@towers[0].length == 0 && @towers[2].length == 0)
  end

end

new_game = TowersOfHanoi.new

new_game.play