ananumber

#!/usr/bin/env ruby
##############################################################################################
require 'epitools'
##############################################################################################

NUMBER_MAP = {
  "1" => %w[1],
  "2" => %w[a b c],
  "3" => %w[d e f],
  "4" => %w[g h i],
  "5" => %w[j k l],
  "6" => %w[m n o],
  "7" => %w[p q r s],
  "8" => %w[t u v],
  "9" => %w[w x y z],
  "0" => %w[0],
}

def each_letter_sequence_for(numstr, &block)
  if numstr.empty?
    yield ""
  else
    char = numstr[0]

    if letters = NUMBER_MAP[char]
      letters.each do |letter|
        each_letter_sequence_for(numstr[1..-1]) do |str|
          yield letter + str
        end
      end
    end
  end
end

##############################################################################################

if $0 == __FILE__
  if ARGV.any?
    numstr = ARGV.join.scan(/\d/).flatten.join

    lesspipe do |less|
      less.puts "------------------------------------------------------"
      less.puts "All permutations of #{numstr}"
      less.puts "------------------------------------------------------"
      each_letter_sequence_for(numstr) { |seq| less.puts seq }
    end
  else
    puts "Usage: ananumber <phone digits>"
  end
end