#!/usr/bin/runghc

module SimpleSubCipher where

import Data.List qualified as L

letters :: String
letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

translateChar :: String -> String -> Char -> Char
translateChar string1 string2 char = case L.elemIndex char string1 of
  Nothing -> char
  Just index -> string2 !! index

translateString :: String -> String -> String -> String
translateString string1 string2 = map (translateChar string1 string2)

main :: IO ()
main = do
  let message = "THIS IS A SHORT MESSAGE"
  let key = "LFWOAYUISVKMNXPBDCRJTQEGHZ"
  putStrLn "Your encrypted message is:"
  putStrLn (translateString letters key message)
  putStrLn "Your decrypted ciphertext is:"
  putStrLn (translateString key letters (translateString letters key message))