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{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TupleSections #-}
module Thermoprint.Server.API
( ProtoHandler, Handler
, thermoprintServer
, handlerNat
) where
import Thermoprint.API hiding (JobId(..), DraftId(..))
import qualified Thermoprint.API as API (JobId(..), DraftId(..))
import Thermoprint.Server.Printer
import Thermoprint.Server.Database
import Data.Set (Set)
import qualified Data.Set as Set
import Data.Sequence (Seq)
import qualified Data.Sequence as Seq
import Data.Map (Map)
import qualified Data.Map as Map
import Servant
import Servant.Server
import Servant.Server.Internal.Enter
import Control.Monad.Logger
import Control.Monad.Reader
import Control.Monad.Trans.Resource
import Control.Monad.Trans.Either
import Control.Monad.IO.Class
import Control.Concurrent.STM
import Control.Monad ((<=<), liftM2)
import Prelude hiding ((.), id, mapM)
import Control.Category
import Data.Foldable (toList)
import Data.Traversable (mapM)
import Data.Bifunctor
import Data.Monoid
import Data.Maybe
import Database.Persist
import Database.Persist.Sql
type ProtoHandler = ReaderT HandlerInput (LoggingT (ResourceT IO))
type Handler = EitherT ServantErr ProtoHandler
-- ^ Runtime configuration of our handlers
data HandlerInput = HandlerInput { sqlPool :: ConnectionPool -- ^ How to interact with 'persistent' storage
, printers :: Map PrinterId Printer
}
handlerNat :: ( MonadReader ConnectionPool m
, MonadLoggerIO m
) => Map PrinterId Printer -> m (Handler :~> EitherT ServantErr IO)
-- ^ Servant requires its handlers to be 'EitherT ServantErr IO'
--
-- This generates a 'Nat'ural transformation for squashing the monad-transformer-stack we use in our handlers to the monad 'servant-server' wants
handlerNat printerMap = do
sqlPool <- ask
logFunc <- askLoggerIO
let
handlerInput = HandlerInput
{ sqlPool = sqlPool
, printers = printerMap
}
protoNat :: ProtoHandler :~> IO
protoNat = Nat runResourceT . Nat (($ logFunc) . runLoggingT) . runReaderTNat handlerInput
return $ hoistNat protoNat
thermoprintServer :: ServerT ThermoprintAPI Handler
-- ^ A 'servant-server' for 'ThermoprintAPI'
thermoprintServer = listPrinters
:<|> (listJobs :<|> queueJob)
:<|> getJob <||> jobStatus <||> deleteJob
:<|> (listDrafts :<|> addDraft)
:<|> updateDraft <||> getDraft <||> deleteDraft <||> printDraft
where
-- :: (a -> b) -> (a -> c) -> (a -> b :<|> c)
(<||>) :: Monad m => m a -> m b -> m (a :<|> b)
(<||>) = liftM2 (:<|>)
infixr 9 <||>
lookupPrinter :: Maybe PrinterId -> Handler (PrinterId, Printer)
lookupPrinter pId = asks printers >>= maybePrinter' pId
where
maybePrinter' Nothing printerMap
| Map.null printerMap = left $ err501 { errBody = "No printers available" }
| otherwise = return $ Map.findMin printerMap
maybePrinter (Just pId) printerMap
| Just printer <- Map.lookup pId printerMap = return (pId, printer)
| otherwise = left $ err404 { errBody = "No such printer" }
queue' :: MonadIO m => Printer -> m Queue
queue' = liftIO . readTVarIO . queue
extractJobs :: (PrinterId, Queue) -> Seq (API.JobId, JobStatus)
extractJobs (pId, Queue pending current history) = fmap (, Queued pId) pending' <> maybe Seq.empty Seq.singleton (fmap (, Printing pId) current') <> fmap (second $ maybe Done Failed) history'
where
pending' = fmap (castId' . unJobKey) pending
current' = fmap (castId' . unJobKey) current
history' = fmap (first $ castId' . unJobKey) history
listPrinters :: Handler (Map PrinterId PrinterStatus)
listPrinters = fmap toStatus <$> (mapM (liftIO . readTVarIO . queue) . printers =<< ask)
where
toStatus (Queue _ Nothing _) = Available
toStatus (Queue _ (Just id) _) = Busy . castId $ fromSqlKey id
queueJob :: Maybe PrinterId -> Printout -> Handler API.JobId
queueJob pId printout = lift . fmap (castId' . unJobKey) . withReaderT sqlPool . addToQueue printout . snd =<< lookupPrinter pId
printerStatus :: PrinterId -> Handler PrinterStatus
printerStatus = fmap queueToStatus . queue' . snd <=< lookupPrinter . Just
where
queueToStatus (Queue _ Nothing _) = Available
queueToStatus (Queue _ (Just id) _) = Busy . castId' $ unJobKey id
listJobs :: Maybe PrinterId -> Maybe API.JobId -> Maybe API.JobId -> Handler (Seq (API.JobId, JobStatus))
listJobs Nothing minId maxId = fmap mconcat . mapM (\pId -> listJobs (Just pId) minId maxId) =<< asks (Map.keys . printers)
listJobs pId minId maxId = fmap (filterJobs . extractJobs) . (\(a, b) -> (,) a <$> queue' b) =<< lookupPrinter pId
where
filterJobs = Seq.filter (\(id, _) -> maybe True (< id) minId && maybe True (> id) maxId)
getJob :: API.JobId -> Handler Printout
getJob jobId = fmap jobContent . maybe (left err404) return =<< runSqlPool (get . JobKey . SqlBackendKey $ castId jobId) =<< asks sqlPool
jobStatus :: API.JobId -> Handler JobStatus
jobStatus jobId = maybe (left err404) return . lookup jobId . toList =<< listJobs Nothing Nothing Nothing
deleteJob :: API.JobId -> Handler ()
deleteJob = return undefined
listDrafts :: Handler (Map API.DraftId (Maybe DraftTitle))
listDrafts = return undefined
addDraft :: Maybe DraftTitle -> Printout -> Handler API.DraftId
addDraft = return undefined
updateDraft :: API.DraftId -> Maybe DraftTitle -> Printout -> Handler ()
updateDraft = return undefined
getDraft :: API.DraftId -> Handler (Maybe DraftTitle, Printout)
getDraft = return undefined
deleteDraft :: API.DraftId -> Handler ()
deleteDraft = return undefined
printDraft :: API.DraftId -> Maybe PrinterId -> Handler API.JobId
printDraft = return undefined
|
