{-# OPTIONS -Wall -Werror #-}
-- #hide
module Data.Time.LocalTime.LocalTime
(
-- * Local Time
LocalTime(..),
-- converting UTC and UT1 times to LocalTime
utcToLocalTime,localTimeToUTC,ut1ToLocalTime,localTimeToUT1,
ZonedTime(..),utcToZonedTime,zonedTimeToUTC,getZonedTime,utcToLocalZonedTime
) where
import Data.Time.LocalTime.TimeOfDay
import Data.Time.LocalTime.TimeZone
import Data.Time.Calendar
import Data.Time.Clock
-- | A simple day and time aggregate, where the day is of the specified parameter,
-- and the time is a TimeOfDay.
-- Conversion of this (as local civil time) to UTC depends on the time zone.
-- Conversion of this (as local mean time) to UT1 depends on the longitude.
data LocalTime = LocalTime {
localDay :: Day,
localTimeOfDay :: TimeOfDay
} deriving (Eq,Ord)
instance Show LocalTime where
show (LocalTime d t) = (showGregorian d) ++ " " ++ (show t)
-- | show a UTC time in a given time zone as a LocalTime
utcToLocalTime :: TimeZone -> UTCTime -> LocalTime
utcToLocalTime tz (UTCTime day dt) = LocalTime (addDays i day) tod where
(i,tod) = utcToLocalTimeOfDay tz (timeToTimeOfDay dt)
-- | find out what UTC time a given LocalTime in a given time zone is
localTimeToUTC :: TimeZone -> LocalTime -> UTCTime
localTimeToUTC tz (LocalTime day tod) = UTCTime (addDays i day) (timeOfDayToTime todUTC) where
(i,todUTC) = localToUTCTimeOfDay tz tod
-- | 1st arg is observation meridian in degrees, positive is East
ut1ToLocalTime :: Rational -> UniversalTime -> LocalTime
ut1ToLocalTime long (ModJulianDate date) = LocalTime (ModifiedJulianDay localMJD) (dayFractionToTimeOfDay localToDOffset) where
localTime = date + long / 360 :: Rational
localMJD = floor localTime
localToDOffset = localTime - (fromIntegral localMJD)
-- | 1st arg is observation meridian in degrees, positive is East
localTimeToUT1 :: Rational -> LocalTime -> UniversalTime
localTimeToUT1 long (LocalTime (ModifiedJulianDay localMJD) tod) = ModJulianDate ((fromIntegral localMJD) + (timeOfDayToDayFraction tod) - (long / 360))
-- | A local time together with a TimeZone.
data ZonedTime = ZonedTime {
zonedTimeToLocalTime :: LocalTime,
zonedTimeZone :: TimeZone
}
utcToZonedTime :: TimeZone -> UTCTime -> ZonedTime
utcToZonedTime zone time = ZonedTime (utcToLocalTime zone time) zone
zonedTimeToUTC :: ZonedTime -> UTCTime
zonedTimeToUTC (ZonedTime t zone) = localTimeToUTC zone t
instance Show ZonedTime where
show (ZonedTime t zone) = show t ++ " " ++ show zone
instance Show UTCTime where
show t = show (utcToZonedTime utc t)
getZonedTime :: IO ZonedTime
getZonedTime = do
t <- getCurrentTime
zone <- getTimeZone t
return (utcToZonedTime zone t)
-- |
utcToLocalZonedTime :: UTCTime -> IO ZonedTime
utcToLocalZonedTime t = do
zone <- getTimeZone t
return (utcToZonedTime zone t)