-- Simple test wrapper for Cesar Cipher example
--
-- Usage: ./TestCesar <filename>
-- Compile like this: ghc --make -o TestCesar TestCesar.hs
-- 
-- Reads text from the given file, splits it into lines,
-- encodes each line, decodes each line and checks
-- whether the decoded text matches the input text.
-----------------------------------------------------------------------------

module Main where

import System.Environment
import System.IO
import System.Random
import Cesar

main = do
        args <- getArgs           -- read command line arguments :: [String]
        let [fn] = args           -- exactly 1 argument required: filename
        contents <- readFile fn   -- read entire contents as string
        let strs = lines contents -- split by lines
        key <- getStdRandom (randomR (1,25))  -- randomly generated key
        let cs = map (encode key) strs        -- encode all lines
        let zs = map crack cs                 -- decode all lines
        putStrLn $ unlines                    -- check for equality and print result
                   [if ok then "Crack successful" else ("Crack failed on string: "++str )
                   | (str,c,z) <- zip3 strs cs zs, let ok = crack c == str ]