{-# LANGUAGE OverloadedStrings #-}
module Network.EngineIO.Snap (snapAPI) where

import qualified Control.Exception.Lifted as MonadCatchIO
import qualified System.IO.Streams.Attoparsec as IOStreams
import qualified Data.ByteString.Builder as Builder
import qualified Data.HashMap.Strict as HashMap
import qualified Data.Map.Lazy as LMap
import qualified Network.EngineIO as EIO
import qualified Network.WebSockets.Snap as Snap
import qualified Snap.Core as Snap

--------------------------------------------------------------------------------
-- | A drop in 'EIO.ServerAPI' that works in any Snap monad - including both
-- @Handler@ and @Snap@.
snapAPI :: Snap.MonadSnap m => EIO.ServerAPI m
snapAPI = EIO.ServerAPI
  { EIO.srvTerminateWithResponse = \code ct body -> do
      Snap.modifyResponse $ Snap.setResponseCode code . Snap.setContentType ct
      Snap.writeLBS $ Builder.toLazyByteString body
      Snap.getResponse >>= Snap.finishWith

  , EIO.srvGetQueryParams =
      LMap.foldlWithKey' (\m k v -> HashMap.insert k v m) HashMap.empty
        <$> Snap.getQueryParams

  , EIO.srvParseRequestBody =
      fmap (either (\e@IOStreams.ParseException{} -> Left (show e))
                   Right) .
      MonadCatchIO.try . Snap.runRequestBody . IOStreams.parseFromStream

  , EIO.srvGetRequestMethod = do
      m <- Snap.getsRequest Snap.rqMethod
      return $ case m of
        Snap.GET -> "GET"
        Snap.POST -> "POST"
        Snap.HEAD -> "HEAD"
        Snap.PUT -> "PUT"
        Snap.DELETE -> "DELETE"
        Snap.TRACE -> "TRACE"
        Snap.OPTIONS -> "OPTIONS"
        Snap.CONNECT -> "CONNECT"
        Snap.PATCH -> "PATCH"
        Snap.Method method -> method

  , EIO.srvRunWebSocket = Snap.runWebSocketsSnap
  }