basic data types for scheduled activities

Rather similar to crontab, although with a different format.
But with less emphasis on per-minute scheduling.
Also, supports weekly events, which cron makes too hard.
Also, has a duration field.

Utility/Misc.hs

@@ -29,7 +29,7 @@ hGetContentsStrict = hGetContents >=> \s -> length s `seq` return s
 readFileStrict :: FilePath -> IO String
 readFileStrict = readFile >=> \s -> length s `seq` return s
 
-{- Like break, but the character matching the condition is not included
+{- Like break, but the item matching the condition is not included
  - in the second result list.
  -
  - separate (== ':') "foo:bar" = ("foo", "bar")

Utility/Scheduled.hs

@@ -0,0 +1,116 @@
+{- scheduled activities
+ - 
+ - Copyright 2013 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Utility.Scheduled (
+	Schedule(..),
+	Recurrance(..),
+	TimeOfDay(..),
+	fromSchedule,
+	toSchedule
+) where
+
+import Common
+
+{- Some sort of scheduled event. -}
+data Schedule = Schedule Recurrance TimeOfDay Duration
+  deriving (Show)
+
+data Recurrance
+	= Daily
+	| Weekly WeekDay
+	| Monthly MonthDay
+	| Yearly YearDay
+	-- Divisible 3 Daily is every day of the year evenly divisible by 3
+	| Divisable Int Recurrance
+  deriving (Show)
+
+type WeekDay = Int
+type MonthDay = Int
+type YearDay = Int
+
+data TimeOfDay
+	= AnyTime
+	| Hour Int
+  deriving (Show)
+
+data Duration = MinutesDuration Int
+  deriving (Show)
+
+fromRecurrance :: Recurrance -> String
+fromRecurrance (Divisable n r) =
+	fromRecurrance' (++ "s divisible by " ++ show n) r
+fromRecurrance r = fromRecurrance' ("every " ++) r
+
+fromRecurrance' :: (String -> String) -> Recurrance -> String
+fromRecurrance' a Daily = a "day"
+fromRecurrance' a (Weekly n) = onday n (a "week")
+fromRecurrance' a (Monthly n) = onday n (a "month")
+fromRecurrance' a (Yearly n) = onday n (a "year")
+fromRecurrance' a (Divisable _n r) = fromRecurrance' a r -- not used
+
+onday :: Int -> String -> String
+onday n s = s ++ " on day " ++ show n
+
+toRecurrance :: String -> Maybe Recurrance
+toRecurrance s = case words s of
+	("every":something:l) -> parse something l
+	(something:"divisible":"by":sn:l) -> do
+		r <- parse something l
+		n <- readish sn
+		if n > 0
+			then Just $ Divisable n r
+			else Nothing
+	_ -> Nothing
+  where
+	parse "day" [] = Just Daily
+	parse "week" l = withday Weekly l
+	parse "month" l = withday Monthly l
+	parse "year" l = withday Yearly l
+	parse v l
+		| "s" `isSuffixOf` v = parse (reverse $ drop 1 $ reverse v) l
+		| otherwise = Nothing
+	withday a ("on":"day":n:[]) = a <$> readish n
+	withday _ _ = Nothing
+
+fromTimeOfDay :: TimeOfDay -> String
+fromTimeOfDay AnyTime = "any time"
+fromTimeOfDay (Hour n) = "hour " ++ show n
+
+toTimeOfDay :: String -> Maybe TimeOfDay
+toTimeOfDay s = case words s of
+	("any":"time":[]) -> Just AnyTime
+	("hour":n:[]) -> Hour <$> readish n
+	_ -> Nothing
+
+fromDuration :: Duration -> String
+fromDuration (MinutesDuration n) = show n ++ " minutes"
+
+toDuration :: String -> Maybe Duration
+toDuration s = case words s of
+	(n:"minutes":[]) -> MinutesDuration <$> readish n
+	(n:"minute":[]) -> MinutesDuration <$> readish n
+	_ -> Nothing
+
+fromSchedule :: Schedule -> String
+fromSchedule (Schedule recurrance timeofday duration) = unwords
+	[ fromRecurrance recurrance
+	, "at"
+	, fromTimeOfDay timeofday
+	, "for"
+	, fromDuration duration
+	]
+
+toSchedule :: String -> Maybe Schedule
+toSchedule s = Schedule
+	<$> toRecurrance (unwords recurrance)
+	<*> toTimeOfDay (unwords timeofday)
+	<*> toDuration (unwords duration)
+  where
+  	ws = words s
+	(recurrance, ws') = separate (== "at") ws
+	(timeofday, duration) = separate (== "for") ws'
+