Request.hs

{-# LANGUAGE DuplicateRecordFields, DeriveGeneric #-}
-- |
-- Module: Network.Greskell.WebSocket.Request
-- Description: Request to Gremlin Server
-- Maintainer: Toshio Ito <debug.ito@gmail.com>
--
-- 
module Network.Greskell.WebSocket.Request
       ( -- * RequestMessage
         RequestMessage(..),
         Operation(..),
         toRequestMessage,
         makeRequestMessage
       ) where

import Control.Applicative ((<$>), (<*>))
import Data.Aeson (Object, ToJSON(..), FromJSON(..))
import Data.Text (Text)
import Data.UUID (UUID)
import Data.UUID.V4 (nextRandom)
import GHC.Generics (Generic)

import qualified Network.Greskell.WebSocket.Request.Aeson as GAeson
import Network.Greskell.WebSocket.Request.Common (Operation(..))


-- | RequestMessage to a Gremlin Server. See
-- <http://tinkerpop.apache.org/docs/current/dev/provider/>.
data RequestMessage =
  RequestMessage
  { requestId :: !UUID,
    op :: !Text,
    processor :: !Text,
    args :: !Object
  }
  deriving (Show,Eq,Generic)

instance ToJSON RequestMessage where
  toJSON = GAeson.genericToJSON GAeson.opt
  toEncoding = GAeson.genericToEncoding GAeson.opt

instance FromJSON RequestMessage where
  parseJSON = GAeson.genericParseJSON GAeson.opt

-- | Convert an 'Operation' object to 'RequestMessage'.
toRequestMessage :: Operation o => UUID -> o -> RequestMessage
toRequestMessage rid o =
  RequestMessage { requestId = rid,
                   op = opName o,
                   processor = opProcessor o,
                   args = opArgs o
                 }

-- | Create a 'RequestMessage' from an 'Operation' object. The
-- 'requestId' is generated by the random number generator of the
-- system.
makeRequestMessage :: Operation o => o -> IO RequestMessage
makeRequestMessage o = toRequestMessage <$> nextRandom <*> pure o