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{-# LANGUAGE FlexibleContexts, ScopedTypeVariables, ViewPatterns, ConstraintKinds, TupleSections, RecordWildCards, TypeFamilies #-}
module Postdelay.TimeSpec
( timeSpec
, timeZone
, spaceConsumer, lexeme
) where
import Postdelay.TimeSpec.Utils
import Postdelay.TimeSpec.Units
import Text.Megaparsec
import Control.Monad.IO.Class
import Control.Applicative
import Control.Lens hiding ((#))
import Control.Exception (IOException)
import Control.Monad.Catch
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)
utcOffset :: Iso' TimeZone Time
utcOffset = iso ((% Minute) . fromIntegral . timeZoneMinutes) (minutesToTimeZone . round . (# Minute))
timeSpec :: StringParser s m => m (Endo LocalTime)
timeSpec = label "Relative time specification" $
choice [ lexeme (string' "now") *> offsets True
, offsets False
]
offsets :: forall s m. StringParser s m
=> Bool -- ^ Require sign on first offset?
-> m (Endo LocalTime)
offsets reqSgn = fmap fold $ (:) <$> offset reqSgn <*> many (offset False)
where
asOffset :: Time -> Endo LocalTime
asOffset by = Endo $ flexDT.seconds' %~ (^+^ by)
offset :: Bool -> m (Endo LocalTime)
offset sgnReq@(bool optSigned signed -> sgn)
= asOffset <$> lexeme (sgn timeLength) <?> if sgnReq then "Signed time offset" else "Time offset"
timeZone :: (StringParser s m, MonadIO m) => m (Either TimeZone TZ)
timeZone = label "Timezone" $ (Left <$> numericTimezone) <|> (Right <$> namedTimezone)
numericTimezone :: StringParser s m => m TimeZone
numericTimezone = review utcOffset <$> (sign <*> ((^+^) <$> hour <*> minute)) <?> "Numeric timezone"
where
hour = (% Hour) <$> twoDigit
minute = (% Minute) <$> twoDigit
twoDigit = (\n1 n2 -> fromDigit n1 * 10 + fromDigit n2) <$> digitChar <*> digitChar
namedTimezone :: (StringParser s m, MonadIO m) => m TZ
namedTimezone = do
n <- ident
tz <- liftIO $ do
let
fbHandler :: IO a -> (IOException -> IO a)
fbHandler fb _ = fb
foldl (\fb a -> a `catch` fbHandler fb) (return Nothing)
[ Just <$> loadSystemTZ n
, Just <$> loadTZFromDB n
]
case tz of
Nothing -> fail $ "Could not resolve timezone: " ++ show n
(Just tz) -> return tz
where
asciiAlphaNum = oneOf $ ['0'..'9'] ++ ['a'..'z'] ++ ['A'..'Z']
ident = (++) <$> some asciiAlphaNum <*> option [] ((:) <$> oneOf "_-/.+" <*> ident) <?> "Named timezone identifier"
|
