Project Euler59

class P59
  def initialize
    @w_the = "the ".split("").map(&:ord)
  end

  def main
    encorded_words = read_file( "cipher1.txt" )
    
    ("a".ord.."z".ord).each do |key0|
      ("a".ord.."z".ord).each do |key1|
        ("a".ord.."z".ord).each do |key2|

          decoded_words = decode( encorded_words, [key0, key1, key2] )
          return decoded_words.inject(:+) if real_words?( decoded_words )

        end
      end
    end
  end

  def real_words?( words )
    (0..3).any? do |shift|
      words.drop(shift).each_slice(4).any? { |w_four| w_four == @w_the }
    end
  end

  def decode( words, key )
    words.map.with_index do |word, idx|
      word ^ key[idx % 3]
    end
  end

  def read_file( fn )
    line = ""
    open( fn ) do |fp|
      line = fp.read.chomp
    end
    line.split(',').map(&:to_i)
  end
end

if $0 == __FILE__
  p P59.new.main
end