module Message (
      Connected
    , receive
    , send
  ) where

import Control.Monad.Reader (ReaderT, ask, lift)
import Network.WebSockets (Connection, receiveData, sendTextData)
import Data.Aeson (encode, eitherDecode')
import qualified Message.Client as Client (Message)
import qualified Message.Server as Server (Message(..))

type Connected a = ReaderT Connection IO a

send :: Server.Message -> Connected ()
send message = do
  connection <- ask
  lift $ sendTextData connection $ encode message

receive :: Connected Client.Message
receive = do
  connection <- ask
  received <- lift $ receiveData connection
  case eitherDecode' received of
    Left message -> send (Server.Error message) >> receive
    Right message -> return message