{-# LANGUAGE DataKinds           #-}
{-# LANGUAGE GADTs               #-}
{-# LANGUAGE LambdaCase          #-}
{-# LANGUAGE OverloadedStrings   #-}
{-# LANGUAGE RankNTypes          #-}
{-# LANGUAGE RecordWildCards     #-}
{-# LANGUAGE ScopedTypeVariables #-}

module Network.GRPC.HighLevel.Server.Unregistered where

import           Control.Arrow
import           Control.Concurrent.Async                  (async, wait)
import qualified Control.Exception                         as CE
import           Control.Monad
import           Data.Foldable                             (find)
import           Network.GRPC.HighLevel.Server
import           Network.GRPC.LowLevel
import qualified Network.GRPC.LowLevel.Call.Unregistered   as U
import qualified Network.GRPC.LowLevel.Server.Unregistered as U
import           Proto3.Suite.Class

dispatchLoop :: Server
             -> (String -> IO ())
             -> MetadataMap
             -> [Handler 'Normal]
             -> [Handler 'ClientStreaming]
             -> [Handler 'ServerStreaming]
             -> [Handler 'BiDiStreaming]
             -> IO ()
dispatchLoop s logger md hN hC hS hB =
  forever $ U.withServerCallAsync s $ \sc ->
    case findHandler sc allHandlers of
      Just (AnyHandler ah) -> case ah of
        UnaryHandler _ h        -> unaryHandler sc h
        ClientStreamHandler _ h -> csHandler sc h
        ServerStreamHandler _ h -> ssHandler sc h
        BiDiStreamHandler _ h   -> bdHandler sc h
      Nothing                   -> unknownHandler sc
  where
    allHandlers = map AnyHandler hN ++ map AnyHandler hC
                  ++ map AnyHandler hS ++ map AnyHandler hB

    findHandler sc = find ((== U.callMethod sc) . anyHandlerMethodName)

    unaryHandler :: (Message a, Message b) => U.ServerCall -> ServerHandler a b -> IO ()
    unaryHandler sc h =
      handleError $
        U.serverHandleNormalCall' s sc md $ \_sc' bs ->
          convertServerHandler h (const bs <$> U.convertCall sc)

    csHandler :: (Message a, Message b) => U.ServerCall -> ServerReaderHandler a b -> IO ()
    csHandler sc = handleError . U.serverReader s sc md . convertServerReaderHandler

    ssHandler :: (Message a, Message b) => U.ServerCall -> ServerWriterHandler a b -> IO ()
    ssHandler sc = handleError . U.serverWriter s sc md . convertServerWriterHandler

    bdHandler :: (Message a, Message b) => U.ServerCall -> ServerRWHandler a b -> IO ()
    bdHandler sc = handleError . U.serverRW s sc md . convertServerRWHandler

    unknownHandler :: U.ServerCall -> IO ()
    unknownHandler sc = void $ U.serverHandleNormalCall' s sc md $ \_ _ ->
      return (mempty, mempty, StatusNotFound, StatusDetails "unknown method")

    handleError :: IO a -> IO ()
    handleError = (handleCallError logger . left herr =<<) . CE.try
      where herr (e :: CE.SomeException) = GRPCIOHandlerException (show e)

serverLoop :: ServerOptions -> IO ()
serverLoop ServerOptions{..} = do
  -- We run the loop in a new thread so that we can kill the serverLoop thread.
  -- Without this fork, we block on a foreign call, which can't be interrupted.
  tid <- async $ withGRPC $ \grpc ->
    withServer grpc config $ \server -> do
      dispatchLoop server
                   optLogger
                   optInitialMetadata
                   optNormalHandlers
                   optClientStreamHandlers
                   optServerStreamHandlers
                   optBiDiStreamHandlers
  wait tid
  where
    config = ServerConfig
      { host                             = optServerHost
      , port                             = optServerPort
      , methodsToRegisterNormal          = []
      , methodsToRegisterClientStreaming = []
      , methodsToRegisterServerStreaming = []
      , methodsToRegisterBiDiStreaming   = []
      , serverArgs                       =
          [CompressionAlgArg GrpcCompressDeflate | optUseCompression]
          ++
          [ UserAgentPrefix optUserAgentPrefix
          , UserAgentSuffix optUserAgentSuffix
          ]
      , sslConfig = optSSLConfig
      }