module Main where

import Control.Concurrent.Reactive 
import Control.Concurrent
import System.IO

data ProgressReport = ProgressReport
	{ pr_text	:: String -> IO ()	-- say something
	, pr_progress	:: String -> IO ()	-- temp message, overwritten by next message, or text
        , pr_done       :: IO ()		-- wait for the object to finish, and delete it
	}


mkProgressReport :: Handle -> IO ProgressReport
mkProgressReport h =
	reactiveObjectIO state (\ _pid req act done ->  
	    ProgressReport 
		   { pr_text = \ str -> act $ \ st -> do unwind st
						 	 hPutStr h str
							 hFlush h
							 return ""
		   , pr_progress = \ str -> act $ \ st -> do unwind st
							     hPutStr h str
							     hFlush h
							     return str
                   , pr_done = done
	 	   })
 where
	unwind str = hPutStr h $ ['\b' | _ <- str ] ++ [' ' | _ <- str ] ++ ['\b' | _ <- str ]
	state = ""

main = do
	report <- mkProgressReport stdout
	pr_text report  "Hello: "
	sequence [ do pr_progress report (show n)
		      threadDelay $ 1000 * 1000
		 | n <- [1..10]
		 ]
	pr_text report  "[Done]\n"
        pr_done report
	return ()