Purely relative time specifications

1 files changed, 25 insertions, 3 deletions

diff --git a/lib/Postdelay/TimeSpec.hs b/lib/Postdelay/TimeSpec.hs
index 5c41180..03baf85 100644
--- a/lib/Postdelay/TimeSpec.hs
+++ b/lib/Postdelay/TimeSpec.hs
@@ -14,16 +14,38 @@ import Text.Megaparsec
 
 import Control.Monad.IO.Class
 import Control.Applicative
+import Control.Lens hiding ((#))
 
-import Data.Semigroup
+import Data.Bool
+import Data.Semigroup hiding (option)
 import Data.Monoid (Endo(..))
+import Data.Foldable
+import Data.VectorSpace
 
 import Data.Time
+import Data.Time.Lens
 import Data.Time.Zones
 
 
+seconds' :: Timeable t => Lens' t Time
+seconds' = seconds . iso (% Second) (# Second)
+
+
 pTimeSpec :: StringParser s m => m (Endo LocalTime)
-pTimeSpec = empty
+pTimeSpec = label "Relative time specification" $
+            choice [ pOffsets False
+                   ]
+
+pOffsets :: forall s m. StringParser s m
+         => Bool -- ^ Require sign on first offset?
+         -> m (Endo LocalTime)
+pOffsets (bool optSigned signed -> reqSgn) = fmap fold $ (:) <$> offset reqSgn <*> many (offset optSigned)
+  where
+    asOffset :: Time -> Endo LocalTime
+    asOffset by = Endo $ flexDT.seconds' %~ (^+^ by)
+    offset :: (m Time -> m Time) -> m (Endo LocalTime)
+    offset sgn = asOffset <$> lexeme (sgn timeLength) <?> "Time offset"
 
 pTimeZone :: (StringParser s m, MonadIO m) => m (Either TimeZone TZ)
-pTimeZone = empty
+pTimeZone = label "Timezone" $
+            empty