#!/usr/bin/runghc

module OTP (translateString) where

import Data.Bits as B
import Data.Char as C

-- |
-- >>> translateChar 'k' 'Z'
-- '1'

-- |
-- >>> translateChar 'k' '1'
-- 'Z'
translateChar :: Char -> Char -> Char
translateChar keyChar messageChar = C.chr (B.xor (C.ord keyChar) (C.ord messageChar))

-- |
-- >>> translateString "HIYAVRX ZDVUW RFI AJ DYCPFGMAJKS" "\FS!02v?=S)%10wI!fz\DC2a)H%+0p*(#&de}"
-- "This message is 32 chars long..."

-- |
-- >>> translateString "HIYAVRX ZDVUW RFI AJ DYCPFGMAJKS" "This message is 32 chars long..."
-- "\FS!02v?=S)%10wI!fz\DC2a)H%+0p*(#&de}"
translateString :: String -> String -> String
translateString = zipWith translateChar

main :: IO ()
main = do
  let message = "This message is 32 chars long..."
  let key = "HIYAVRX ZDVUW RFI AJ DYCPFGMAJKS"
  putStrLn "Your encrypted message is (with special characters interpreted):"
  putStrLn (translateString key message)
  putStrLn "Your encrypted message is (with special characters uninterpreted):"
  print (translateString key message)
  putStrLn "Your decrypted ciphertext is:"
  putStrLn (translateString key (translateString key message))