-- |
-- Module      : Foreign.Erlang.OTP
-- Copyright   : (c) Eric Sessoms, 2008
--               (c) Artúr Poór, 2015
--               (c) Arnold Szederjesi-Dragomir, 2021
-- License     : GPL3
-- 
-- Maintainer  : szederjesiarnold@gmail.com
-- Stability   : experimental
-- Portability : portable
--

module Foreign.Erlang.Utilities (
  -- * Miscellaneous utilities
    erlangTimeToSeconds
  , secondsToErlangTime
  ) where

import Foreign.Erlang.Types  (ErlType(..))

-- Erlang's native time format is a tuple: {MegaSeconds, Seconds,
-- MicroSeconds}.  Luckily though, Erlang uses the same epoch, so no
-- further conversion is necessary.

-- | Convert a tuple (from @erlang:now()@) to seconds from Jan 1, 1970.

erlangTimeToSeconds :: Integral a => ErlType -> a
erlangTimeToSeconds (ErlTuple [ErlInt ms, ErlInt s, _]) =
    fromIntegral $ 1000000*ms + s

-- | Convert seconds to an Erlang tuple representing time.

secondsToErlangTime :: Integral a => a -> ErlType
secondsToErlangTime sec = ErlTuple [ErlInt ms, ErlInt s, ErlInt 0]
  where
    (ms, s) = fromIntegral sec `divMod` 1000000