# Splits a mnemonic phrase into several cards. When a card is found, not all of
# the words are known. This increases security. The program is written in Ruby.
# It asks for the phrase and the number of cards during runtime. The phrase is
# never sent (to any servers). It is not a malicious program. Since the source
# code is open source and free, this can be verified.

# Copyright (c) 2021 Marek Küthe
# This work is free. You can redistribute it and/or modify it under the
# terms of the Do What The Fuck You Want To Public License, Version 2,
# as published by Sam Hocevar. See http://www.wtfpl.net/ for more details.

require "securerandom"

print "Number of cards: "
STDOUT.flush
n_cards = gets.chomp.to_i

print "Phase: "
STDOUT.flush
phase = gets.chomp.split

pick_words = []
words_per_cards = phase.length / n_cards
remaining_words = phase.length % n_cards

# Random sorting of words; The words are treated as numbers
for i in 0...(phase.length)
  loop do
    pick_words[i] = SecureRandom.rand(0...(phase.length))
    break if ! pick_words[0...-1].include? pick_words[i]
  end
end

# p pick_words

cards = []
for i in 0...n_cards
  # Adding the number of words to each card
  # Number = number of words / number of cards
  cards[i] = pick_words[(i*words_per_cards)...((i+1)*words_per_cards)]
  
  # It can happen that this calculation does not always work out. The remaining
  # words are added to the first cards.
  if remaining_words != 0
    cards[i] << pick_words[-remaining_words]
    remaining_words -= 1
  end
end

# p cards

# Output of the cards. If a word does not appear in a card, XXXX is output.
for i in 0...(cards.length)
  print "Card #{i + 1}: "
  for j in 0...(phase.length)
    if cards[i].include? j
      print "#{phase[j]},\t"
    else
      print "XXXX,\t"
    end
  end
  puts
end