module Data.Time.RFC1123
    ( format
    , parse
    )
    where

import qualified Text.Parsec as P

import Data.Time
import Data.Time.Calendar.WeekDate
import Data.Time.HTTP.Common
import Data.Time.RFC822 (showRFC822TimeZone)
import Data.Time.RFC1123.Parsec

{-
         The syntax for the date is hereby changed to:

            date = 1*2DIGIT month 2*4DIGIT
-}

format :: ZonedTime -> String
format zonedTime
    = let localTime          = zonedTimeToLocalTime zonedTime
          timeZone           = zonedTimeZone zonedTime
          (year, month, day) = toGregorian (localDay localTime)
          (_, _, week)       = toWeekDate  (localDay localTime)
          timeOfDay          = localTimeOfDay localTime
      in
        concat [ shortWeekDayName week
               , ", "
               , show2 day
               , " "
               , shortMonthName month
               , " "
               , show4 year
               , " "
               , show2 (todHour timeOfDay)
               , ":"
               , show2 (todMin timeOfDay)
               , ":"
               , show2 (floor (todSec timeOfDay))
               , " "
               , showRFC822TimeZone timeZone
               ]

parse :: String -> Maybe ZonedTime
parse src = case P.parse p "" src of
              Right zt -> Just zt
              Left  _  -> Nothing
    where
      p = do zt <- rfc1123DateAndTime
             _  <- P.eof
             return zt