lab4.hs

import Control.Monad
import Control.Concurrent
import System.Random
import System.Environment
import Data.List
import Data.Maybe

sec :: Int
sec = 1000000

main :: IO()
main = do
	--inp1 <- getLine
	--inp2 <- getLine
	args <- getArgs

	let brOkvira = read $ head args :: Int 		--read inp1 :: Int
	let brZahtjeva = read $ args !! 1 :: Int  	--read inp2 :: Int

	mv <- newEmptyMVar
	forkIO (mainThreadWrap   mv brZahtjeva brOkvira)
	forkIO (secondThreadWrap mv brZahtjeva brOkvira)
	threadDelay $ sec * (brZahtjeva * 2 + 1)
	return ()

type Zahtjev = String

mainThreadWrap :: MVar Zahtjev -> Int -> Int -> IO()
mainThreadWrap mv zahtjeva1 okvira = do
	zahtjevi <- replicateM zahtjeva1 $ takeMVar mv
	mainThreadLoop zahtjevi (replicate okvira "") 0 $ 2*zahtjeva1 -- predaju se zahtjevi i broj zahtjeva
	where
		mainThreadLoop :: [Zahtjev] -> [Zahtjev] -> Int -> Int -> IO()
		mainThreadLoop zahtjevi okviri tren zahtjeva = do
			threadDelay sec
			new <- tryTakeMVar mv
			let zahtjevi2 = zahtjevi ++ maybe [] return new
			putStrLn $ fst $ obradi zahtjevi okviri tren okvira zahtjeva1 -- obradi se predaju zahtjevi i broj okvira
			unless (zahtjeva == 0) $ uncurry (mainThreadLoop (tail zahtjevi2)) (snd $ obradi zahtjevi okviri tren okvira zahtjeva1) (zahtjeva-1)


secondThreadWrap :: MVar Zahtjev -> Int -> Int -> IO()
secondThreadWrap mv zahtjeva _ = do
	replicateM_ zahtjeva nextMVar
	sequence_ $ take (zahtjeva*2) $ cycle [nextMVar, threadDelay sec]
	where
		nextMVar = getStdRandom (randomR (0 :: Int, 9 :: Int)) >>= putMVar mv . show

obradi :: [Zahtjev] -> [Zahtjev] -> Int -> Int -> Int -> (String, ([Zahtjev], Int))
obradi zs@(z:_) okviri tren okvira zahtjeva =  (retStr, (noviNepodeseni, noviTren)) -- snd arg "okvira"
	where
		z' = if z `elem` okviri then "("++z++")" else "["++z++"]"
		zahts = intercalate "," zs
		spaces = replicate (2*(zahtjeva - length zs + 2)) ' '
		retStr = zahts ++ spaces ++ show z ++ "  " ++ intercalate "  " noviOkviri
		noviOkviri = if z `elem` okviri then replaceAt (fromJust $ elemIndex z okviri) okviri z' else replaceAt tren okviri z'
		noviNepodeseni = if z `elem` okviri then replaceAt (fromJust $ elemIndex z okviri) okviri z else replaceAt tren okviri z
		noviTren = if z `elem` okviri then tren else (tren+1) `mod` okvira

replaceAt :: Int -> [Zahtjev] -> Zahtjev -> [Zahtjev]
replaceAt wher what with = fs ++ [with] ++ sn
	where (fs, _:sn) = splitAt wher what