Hangman v1

class Hangman
  
  DICTIONARY = %w(pangolin ecstatic oligarchy corridor)
  MAX = 6
  
  def initialize(input=STDIN, output=STDOUT)
    @input = input
    @output = output
    @guesses = 0
  end
  
  def start
    @output.puts "Welcome to Hangman!"
    generate_word
    @current = @word.gsub(/./, "_")
    @output.puts @current
    guess
  end
  
  def guess
    while @guesses < MAX
      # print the word with letters found.  Separate characters with a space.
      @output.puts @current.gsub(/([A-Z_])/, "\\1 ")
      @output.print "Enter a letter. You have #{MAX - @guesses} guesses. "
      input = @input.gets.chomp.upcase
      unless is_letter?(input)
        if input == "QUIT"
          exit
        else
          @output.puts "Please enter a valid character (1 letter)..."
          next
        end
      end

      # if the letter is in the word
      if letter_is_in_word?(input)
        update_word(input)
        # if all letters are replaced, we've found the word, hurray!
        if @current == @word
          @output.puts "Well done! The word was #{@word}"
          exit
        end
      else 
        # if the letter is not in the word, increase guesses number.
        @guesses += 1    
      end
    end
  end
    
  def update_word(input)
    for i in 0...@word.size
      # if current character is the input, replace the '_'
      if @word[i].chr == input
        @current[i] = input
      end
    end
  end
    
  def is_letter?(input)
      # check that the input is one letter
      !(input.size > 1 or not (input =~ /[[:alpha:]]/))
  end
  
  def letter_is_in_word?(input)
    @word.index(input) != nil
  end
  
  def generate_word
      @word = DICTIONARY[rand(DICTIONARY.size)-1].upcase
  end
end