SessionStore.hs

module Network.Socketson.SessionStore where

-- intern:
import Network.Socketson.ServerState
import Network.Socketson.ProtocolException
-- mvar:
import Control.Concurrent.MVar
-- data:
import qualified Data.Serialize  as BIN
import qualified Data.ByteString as BS
import Data.Default
-- leveldb:
import Database.LevelDB
-- either transformer:
import Control.Monad.Trans.Either
import Data.Either.Combinators (mapLeft)

{-----------------
 Session Store

 Stores session data in a levelDB, hashed under generated session keys. The handle gets generated whenever work has to be done; the path to the levelDB files are needed.
-}

{-| Saves given session data (which can be anything which is serializable) under given key, based on the given server state.

  saveSessionData serverState key sessionData
-}
saveSessionData :: (BIN.Serialize a) => ServerState -> BS.ByteString -> a -> IO ()
saveSessionData state key dat =
     runResourceT (do db <- open (storePath state) defaultOptions { createIfMissing = True }
                      put db def key (BIN.encode dat) )



{-| Restores session data which was saved in the session store before, saved under given key, wrapped in a 'Maybe' monad. Returns 'Nothing' if no data was found under given key. -}
restoreSessionData :: (BIN.Serialize a) => ServerState -> BS.ByteString -> EitherT ProtocolException IO a
restoreSessionData state key =
  do res <- runResourceT (do db <- open (storePath state) defaultOptions { createIfMissing = True }
                             get db def key)
     case res of
       Just x  -> hoistEither $ mapLeft (SessionStoreCorruptAt key) (BIN.decode x)
       Nothing -> left (InvalidSessionKey key)