'cause robots should type drunk, too

alcohol.rb

class Array; def random; self[rand(self.count)]; end; end
class Hash; def random; self[self.keys.random]; end; end

class Alcohol
  DRINKING_START = 20
  PEAK_INTOXICATION = 4

  LAYOUT = [
    ['`1234567890-= ',  '~!@#$%^&*()_+ '],
    [' qwertyuiop[]\\', ' QWERTYUIOP{}|'],
    [' asdfghjkl;\'  ', ' ASDFGHJKL:"  '],
    ['  zxcvbnm,./  ',  '  ZXCVBNM<>?  '],
  ].map{|row| row.map {|keys| keys.chars.to_a } }

  MANGLING_RULES = {
    1 => [
      :omit,
      :inject,
      :substitute,
      :repeat,
    ],
    2 => [
      :transpose,
    ],
  }

  class << self
    def mistakes
      @mistakes ||= {}.tap do |m|
        keys = LAYOUT.each_with_index do |row, r|
          row.each_with_index do |keys, shift|
            keys.each_with_index do |key, c|
              m[key] = {}.tap do |h|
                h[:up] = LAYOUT[r-1][shift][c] if r > 0
                h[:right] = LAYOUT[r][shift][c+1] if c < keys.count - 1
                h[:down] = LAYOUT[r+1][shift][c] if r < LAYOUT.count - 1
                h[:left] = LAYOUT[r][shift][c-1] if c > 0
              end
            end
          end
        end
      end
    end

    def omit(letter); ''; end

    def inject(letter)
      side = rand(2)
      addition = mistakes[letter].random
      letter.insert(side, addition)
    end

    def repeat(letter)
      letter + letter
    end

    def substitute(letter)
      mistakes[letter].random
    end

    def transpose(letters)
      letters.reverse
    end

    def mangle(string)
      self.send MANGLING_RULES[string.length].random, string
    end

    def word_mangle_probability
      range_of_time_out = (DRINKING_START...(PEAK_INTOXICATION+24))
      hours_of_drinking = range_of_time_out.count * 1.0
      (range_of_time_out.map{|h| h % 24 }.index(Time.now.hour) || 0) / hours_of_drinking
    end

    def mangle_word(word)
      return word unless rand < word_mangle_probability
      letters_mangled = MANGLING_RULES.keys.random

      sliced = word.chars.to_a
      indices = (0..sliced.length).to_a

      case letters_mangled
      when 1
        num_mangles = 1 + rand(word.length / 3).to_i
        num_mangles.times do
          index = indices.delete_at(rand(indices.count-1).to_i)
          sliced[index] = mangle(sliced[index])
        end
      when 2
        index = rand(word.length-1).to_i
        sliced[index] = mangle(sliced[index] + sliced[index+1])
        sliced.delete_at(index+1)
      end

      sliced.join
    end
  end
end