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|
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DeriveAnyClass #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE DerivingStrategies #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE TypeSynonymInstances #-}
module Server where
import Servant (Application,
FromHttpApiData (parseUrlPiece),
Server, err404, serve, throwError,
type (:>))
import Servant.API (Capture, FromHttpApiData, Get, JSON,
Post, ReqBody, type (:<|>) ((:<|>)))
import Servant.Docs (DocCapture (..), DocQueryParam (..),
ParamKind (..), ToCapture (..),
ToParam (..))
import Control.Concurrent.STM
import Control.Monad.IO.Class (MonadIO (liftIO))
import Data.Aeson (FromJSON (parseJSON), ToJSON (toJSON),
ToJSONKey, genericParseJSON,
genericToJSON)
import qualified Data.Aeson as A
import Data.Functor ((<&>))
import Data.Map (Map)
import qualified Data.Map as M
import Data.Proxy (Proxy (Proxy))
import Data.Swagger
import Data.Text (Text)
import Data.Time (UTCTime (utctDay), dayOfWeek,
getCurrentTime)
import Data.UUID (UUID)
import qualified Data.UUID as UUID
import qualified Data.UUID.V4 as UUID
import Data.Vector (Vector)
import GHC.Foreign (withCStringsLen)
import GHC.Generics (Generic)
import GTFS
import Servant.Server (Handler)
import Servant.Swagger (toSwagger)
newtype Token = Token UUID
deriving newtype (Show, ToJSON, Eq, Ord, FromHttpApiData, ToJSONKey)
instance ToSchema Token where
declareNamedSchema _ = declareNamedSchema (Proxy @String)
instance ToParamSchema Token where
toParamSchema _ = toParamSchema (Proxy @String)
-- TODO: perhaps wrap into server-side struct to add network delay stats?
data TrainPing = TrainPing
{ pingLat :: Float
, pingLong :: Float
, pingDelay :: Int
, pingTimestamp :: Time
} deriving (Generic)
instance FromJSON TrainPing where
parseJSON = genericParseJSON (aesonOptions "ping")
instance ToJSON TrainPing where
toJSON = genericToJSON (aesonOptions "ping")
instance ToSchema TrainPing where
declareNamedSchema = genericDeclareNamedSchema (swaggerOptions "ping")
type KnownTrips = TVar (Map Token [TrainPing])
type API = "stations" :> Get '[JSON] (Map StationID Station)
:<|> "timetable" :> Capture "Station ID" StationID :> Get '[JSON] (Map TripID (Trip Deep))
:<|> "trip" :> Capture "Trip ID" TripID :> Get '[JSON] (Trip Deep)
-- ingress API (put this behind BasicAuth?)
-- TODO: perhaps require a first ping for registration?
:<|> "trainregister" :> Capture "Trip ID" TripID :> Post '[JSON] Token
-- TODO: perhaps a websocket instead?
:<|> "trainping" :> Capture "Train Token" Token :> ReqBody '[JSON] TrainPing :> Post '[JSON] ()
-- debug things
:<|> "debug" :> "state" :> Get '[JSON] (Map Token [TrainPing])
type CompleteAPI = "debug" :> "openapi" :> Get '[JSON] Swagger
:<|> API
server :: GTFS -> KnownTrips -> Server CompleteAPI
server gtfs@GTFS{..} knownTrains = handleDebugAPI :<|> handleStations :<|> handleTimetable :<|> handleTrip
:<|> handleRegister :<|> handleTrainPing :<|> handleDebugState
where handleStations = pure stations
handleTimetable station = do
today <- liftIO getCurrentTime <&> utctDay
pure $ tripsOnDay gtfs today
handleTrip trip = case M.lookup trip trips of
Just res -> pure res
Nothing -> throwError err404
handleRegister tripID = liftIO $ do
token <- UUID.nextRandom <&> Token
atomically $ modifyTVar knownTrains (M.insert token [])
pure token
handleTrainPing token ping = liftIO $ atomically $ do
modifyTVar knownTrains (M.update (\history -> Just (ping : history)) token)
pure ()
handleDebugState = liftIO $ readTVarIO knownTrains
handleDebugAPI = pure $ toSwagger (Proxy @API)
application :: GTFS -> IO Application
application gtfs = do
knownTrips <- newTVarIO mempty
pure $ serve (Proxy @CompleteAPI) $ server gtfs knownTrips
{-
TODO:
there should be a basic API allowing the questions:
- what are the next trips leaving from $station? (or $geolocation?)
- all stops of a given tripID
then the "ingress" API:
- train ping (location, estimated delay, etc.)
- cancel trip
- add trip?
-}
|
