# coding: utf-8
# https://de.wikipedia.org/wiki/Spaltentransposition

class String
  def clean
    self.upcase.chars.filter{ |c| c >= "A" && c <= "Z" }
  end
end

def encrypt(msg, key)
  msg, ret, key = msg.clean.join, "", key.clean
  arr = msg.scan /.{1,#{key.length}}/
  arr = arr.map { |a| a.ljust(key.length).chars }.transpose

  ("A".."Z").each do |c|
    hits = key.each_index.filter{ |i| key[i] == c }
    ret += hits.map{ |a| arr[a].join.rstrip }.join
  end

  return (ret.scan /.{1,5}/).join(" ")
end

def decrypt(msg, key)
  msg, key = msg.clean.join, key.clean
  rows = (msg.length / key.length.to_f).ceil
  pad  = msg.length % key.length
  arr, cnt  = [], 0

  ("A".."Z").each do |c|
    hits = key.each_index.filter{ |i| key[i] == c }
    hits.each do |a|
      p = ((pad != 0) && (a >= pad)) ? rows-1 : rows
      arr[a] = msg[cnt, p]
      cnt += p
    end
  end

  return arr.map{ |a| a.ljust(rows).chars }.transpose.join.rstrip
end

msg = """The Industrial Revolution and its consequences have been a
         disaster for the human race"""

key1 = "uncleted"
key2 = "livesinashed"

msg = msg.clean.join
puts "Original:\t#{msg}"

ret =  encrypt(encrypt(msg, key1), key2)
puts "Encrypted:\t#{ret}"

ret =  decrypt(decrypt(ret, key2), key1)
puts "Decrypted:\t#{ret}"

if ret == msg then puts "SUCCESS" end