1 files changed, 58 insertions, 0 deletions
diff --git a/Propellor/Property/Scheduled.hs b/Propellor/Property/Scheduled.hs
new file mode 100644
index 00000000..42ff0068
--- /dev/null
+++ b/Propellor/Property/Scheduled.hs
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+module Propellor.Property.Scheduled
+	( period
+	, Recurrance(..)
+	, WeekDay
+	, MonthDay
+	, YearDay
+	) where
+
+import Propellor
+import Utility.Scheduled
+
+import Data.Time.Clock
+import Data.Time.LocalTime
+import qualified Data.Map as M
+
+-- | Makes a Property only be checked every so often.
+--
+-- This uses the description of the Property to keep track of when it was
+-- last run.
+period :: Property -> Recurrance -> Property
+period prop recurrance = Property desc $ do
+	lasttime <- getLastChecked (propertyDesc prop)
+	nexttime <- fmap startTime <$> nextTime schedule lasttime
+	t <- localNow
+	if Just t >= nexttime
+		then do
+			r <- ensureProperty prop
+			setLastChecked t (propertyDesc prop)
+			return r
+		else noChange
+  where
+	schedule = Schedule recurrance AnyTime
+	desc = propertyDesc prop ++ " (period " ++ show recurrance ++ ")"
+
+lastCheckedFile :: FilePath
+lastCheckedFile = localdir </> ".lastchecked"
+
+getLastChecked :: Desc -> IO (Maybe LocalTime)
+getLastChecked desc = M.lookup desc <$> readLastChecked
+
+localNow :: IO LocalTime
+localNow = do
+	now <- getCurrentTime
+	tz <- getTimeZone now
+	return $ utcToLocalTime tz now
+
+setLastChecked :: LocalTime -> Desc -> IO ()
+setLastChecked time desc = do
+	m <- readLastChecked
+	writeLastChecked (M.insert desc time m)
+
+readLastChecked :: IO (M.Map Desc LocalTime)
+readLastChecked = fromMaybe M.empty <$> catchDefaultIO Nothing go
+  where
+	go = readish <$> readFile lastCheckedFile
+
+writeLastChecked :: M.Map Desc LocalTime -> IO ()
+writeLastChecked = writeFile lastCheckedFile . show