-- hangman game from Lecture 03A
-- Refactored slightly 

-- Can you see further opportunities for refactoring?
-- Hint: in more than one place we invite the user to input a value (string). 
-- Perhaps this should be abstracted as a function...

-- To compile to a standalone program use
-- ghc --make Hangman.hs


main :: IO()

main = do w <- getWord
          gameLoop "" w


gameLoop :: String -> String -> IO()
gameLoop g w = 
  do if gameOver g w 
      then endGame g 
      else do putStrLn ("Word so far:" ++  progress g w)
              putStrLn ("Guesses so far: " ++ g)
              putStrLn "Guess some characters"
              putStr ">" 
              g' <- getLine
              gameLoop (g' ++ g) w
 
endGame g = 
    do putStrLn ("Yay! You guessed it in " ++ show (length g) ++ " characters")
       putStrLn "(Type Enter key to exit)"  
       getLine
       return ()
       
          
clear :: IO() -- clear screen
clear = putStrLn (replicate screenheight '\n')
        where screenheight = 40 

getWord :: IO(String) -- Get a word from player 1 
getWord = 
   do putStr "Player 1 please type a word\n"
      putStr ">" 
      w <- getLine
      clear
      return w
            
gameOver :: String -> String -> Bool
gameOver g w = and [elem c g | c <- w ]

progress :: String -> String -> String
-- progress "abc" "baby" == "bab*"
progress g w = [if elem c g then c else '*' | c <- w]