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|
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeApplications #-}
-- | An HTTP server providing a basic REPL and text editor to work
-- collaboratively on Minilang code.
module Minilang.Server where
import Control.Concurrent.Async
import Control.Concurrent.STM.TVar
import Control.Exception (try)
import Data.Aeson
( Value,
decode,
eitherDecode,
object,
(.=),
)
import Data.ByteString.Lazy (fromStrict)
import qualified Data.ByteString.Lazy as LBS
import Data.Data (Proxy (..))
import Data.Default
import Data.Text (Text)
import Minilang.API (Challenge, LambdaAPI, defaultChallenges)
import Minilang.App (Env (..), lambdaApp, makeEnv, runApp)
import Minilang.Log
import Minilang.REPL.Net
import Network.Wai
import Network.Wai.Handler.Warp as Warp
import Network.Wai.Middleware.RequestLogger
import Network.Wai.Middleware.RequestLogger.JSON
import Servant (hoistServer)
import Servant.Server (serve)
import System.Log.FastLogger (fromLogStr)
import System.Random (newStdGen)
data Server = Server
{ -- | If the server is running, this will contain the underlying
serverThread :: Maybe (Async ()),
-- | The actual port this server is listening on. Useful when
serverPort :: Int
}
-- | Starts HTTP server on given port.
-- This server serves static files from public/ directory and also
-- exposes a WebSocket-based REPL under `/repl` path.
startServer :: Int -> IO Server
startServer serverPort = do
envs <- newTVarIO mempty
logger <- newLog "minilang"
loggerMiddleware <- runHTTPLog logger
challenges <- readChallenges
env <- newStdGen >>= (`makeEnv` challenges)
let app =
loggerMiddleware $
runNetREPL logger envs (serveAPI env)
(port, action) <- startWarp serverPort app
thread <- async action
logInfo logger $ object ["action" .= ("Started" :: Text), "port" .= port]
pure $ Server (Just thread) port
where
startWarp 0 app = do
(port, socket) <- openFreePort
pure (port, Warp.runSettingsSocket defaultSettings socket app)
startWarp port app = pure (port, Warp.run port app)
runHTTPLog logger =
mkRequestLogger $
def
{ outputFormat = CustomOutputFormatWithDetails formatAsJSON,
destination = Callback (\str -> logInfo logger (decode @Value $ fromStrict $ fromLogStr str))
}
readChallenges :: IO [Challenge]
readChallenges = do
file <- try $ LBS.readFile "challenges.json"
case file of
Left (_ :: IOError) -> pure defaultChallenges
Right content -> case eitherDecode content of
Right challenges -> pure challenges
Left _ -> pure defaultChallenges
serveAPI :: Env -> Application
serveAPI env =
serve apiProxy $
hoistServer apiProxy (runApp env) lambdaApp
apiProxy :: Proxy LambdaAPI
apiProxy = Proxy
stopServer :: Server -> IO ()
stopServer (Server (Just th) _) = cancel th
stopServer _ = pure ()
waitServer :: Server -> IO ()
waitServer (Server (Just th) _) = wait th
waitServer _ = pure ()
|
