-- | Hangman: a word guessing game
-- Functional Programming course 2017.
-- Thomas Hallgren

{-
This started as a skeleton, the definitions were filled in
during the lecture.
-}

import System.Random(randomRIO)
import Data.List(nub)

main = do word <- getRandomWord
          play word []

getRandomWord :: IO String
getRandomWord = do s <- readFile "/usr/share/dict/words"
                   let ws = lines s
                   i <- randomRIO (0,length ws-1)
                   return (ws !! i)

                   
play :: String -> String -> IO ()
play word guesses =
  do putStr [if c `elem` guesses then c else '_' | c<-word]
     putStrLn ("     guesses left: "++show guessesLeft)
     if all (`elem` guesses) word
       then putStrLn "You win!"
       else if guessesLeft <= 0
            then do putStrLn "Sorry, you lost!"
                    putStrLn ("The word was: "++word)
            else do putStrLn "Enter your guess:"
                    s <- getLine
                    play word (s++guesses)
  where
    guessesLeft = length word + 4 - length guesses