# direction = 1
# file = "plain.txt"
# output = "output.txt"

direction = -1
file = "output.txt"
output = "deciphered.txt"

keys = []
File.open("keys.txt","r") do |f|
  f.each_line do |l|
    keys << l.strip
  end
end

lines = []

File.open(file,"r") do |f|
  cnt = 0
  f.each_line do |l|
    lines << l.strip
  end
end

sentences = []
len = lines.length/2
len.times do |i|
  sentences << {:text => lines[i*2],
                :keynum => lines[i*2+1].to_i,
                :key => keys[lines[i*2+1].to_i-1]}
end


def cipher(fwd,text,key)
  over = key.length
  keycnt = 0
  outstr = ""
  text.length.times do |i|
    char = text[i]+key[keycnt]*fwd
    # char = 0 if char < 0
    outstr << char.chr
    keycnt+=1
    keycnt = 0 if keycnt > over - 1
  end
  return outstr
end

sentences.each do |s|
  if s[:key]
    ciphered = cipher(direction,s[:text],s[:key])
    s[:ciphered] = ciphered
  else
    puts "Keys does not exist for #{s[:text]}, skipping"
  end
end

File.open(output,"w") do |f|
  sentences.each do |s|
    if s[:key]
      f.puts s[:ciphered]
      f.puts s[:keynum]
    end
  end
end