-----------------------------------------------------------------------------
-- |
-- Module      :  Data.Term.Persistent
-- 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 Persistent Terms module.
--
-----------------------------------------------------------------------------
module Data.Term.Persistent where

import Control.Monad (IO)
import Data.Unit (Unit)
import Foreign (ffiIO0, ffiIO1, ffiIO2)

type PersistentTermInfo =
  { count  :: Integer
    -- ^ The number of persistent terms.
  , memory :: Integer
    -- ^ The total amount of memory (measured in bytes) used by all persistent terms.
  }

-- | Erase the name for the persistent term with key Key.
erase :: forall k. k -> IO Boolean
erase = ffiIO1 :persistent_term :erase

-- | Retrieve the value for the persistent term associated with the key Key.
get :: forall k v. k -> IO v
get = ffiIO1 :persistent_term :get

-- | Retrieve the value for the persistent term associated with the key Key.
-- Return Default if no term has been stored with the key Key.
getWithDefault :: forall k d v. k -> d -> IO v
getWithDefault = ffiIO2 :persistent_term :get

-- TODO: | Retrieve the keys and values for all persistent terms.
-- getAll :: forall k v. IO (List (k, v))
-- getAll = ffiIO0 "persistent_term" "get"

-- | Return information about persistent terms.
info :: IO PersistentTermInfo
info = ffiIO0 :persistent_term :info

put :: forall k v. k -> v -> IO ()
put = ffiIO2 :persistent_term :put