-----------------------------------------------------------------------------
-- |
-- Module      :  System.Timer
-- Copyright   :  (c) 2020-2021 EMQ Technologies Co., Ltd.
-- License     :  BSD-style (see the LICENSE file)
--
-- Maintainer  :  Feng Lee, feng@emqx.io
--                Yang M, yangm@emqx.io
-- Stability   :  experimental
-- Portability :  portable
--
-- The System Timer module.
--
-----------------------------------------------------------------------------
module System.Timer
  ( TimerRef
  , startTimer
  , cancelTimer
  , sendAfter
  , readTimer
  ) where

import Control.Monad (IO)
import Data.Maybe (Maybe)
import Data.Pid (Pid)
import Data.Ref (Reference)
import Data.Unit (Unit)
import Foreign (ffiIO1, ffiIO3)

type TimerRef = Reference

startTimer :: forall m. Integer -> Pid -> m -> IO TimerRef
startTimer = ffiIO3 :erlang :start_timer

cancelTimer :: TimerRef -> IO ()
cancelTimer = ffiIO1 :erlang :cancel_timer

sendAfter :: forall m. Integer -> Pid -> m -> IO TimerRef
sendAfter = ffiIO3 :erlang :send_after

foreign import readTimer :: TimerRef -> IO (Maybe Integer)