module SWTasks(TaskQueue, mkTaskQueue, later) where

import Graphics.UI.WX

data TaskQueue = TQ (Var [IO ()]) Timer

mkTaskQueue :: Window a -> IO TaskQueue
mkTaskQueue w = do
	vtasks <- varCreate []
	let doTask = do
		xs <- varGet vtasks
		case xs of
		 [] -> return ()
		 (task:tasks) -> do
--			set tim [ enable := False ]
			varSet vtasks tasks
			putStrLn "doing task"
			task
--			set tim [ enable := not (null tasks) ]
	tim <- timer w [interval := 50, on command := doTask, enabled := False]
	return (TQ vtasks tim)

later :: TaskQueue -> IO () -> IO ()
later (TQ vtasks tim) task = do
    tasks <- varGet vtasks
    varSet vtasks (tasks ++ [task])
    set tim [ enabled := True, interval := 50 ]