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module Service (
Service(..),
SomeService(..), SomeServiceState(..),
someServiceID, fromServiceState, someServiceEmptyState,
ServiceID, mkServiceID,
ServiceHandler,
ServiceInput(..),
ServiceReply(..),
handleServicePacket,
svcGet, svcSet,
svcGetLocal, svcSetLocal,
svcPrint,
replyPacket, replyStored, replyStoredRef,
) where
import Control.Monad.Except
import Control.Monad.Reader
import Control.Monad.State
import Control.Monad.Writer
import Data.Typeable
import Data.UUID (UUID)
import qualified Data.UUID as U
import Identity
import State
import Storage
class (Typeable s, Storable s, Typeable (ServiceState s)) => Service s where
serviceID :: proxy s -> ServiceID
serviceHandler :: Stored s -> ServiceHandler s ()
type ServiceState s :: *
type ServiceState s = ()
emptyServiceState :: proxy s -> ServiceState s
default emptyServiceState :: ServiceState s ~ () => proxy s -> ServiceState s
emptyServiceState _ = ()
data SomeService = forall s. Service s => SomeService (Proxy s)
data SomeServiceState = forall s. Service s => SomeServiceState (Proxy s) (ServiceState s)
someServiceID :: SomeService -> ServiceID
someServiceID (SomeService s) = serviceID s
fromServiceState :: Service s => proxy s -> SomeServiceState -> Maybe (ServiceState s)
fromServiceState _ (SomeServiceState _ s) = cast s
someServiceEmptyState :: SomeService -> SomeServiceState
someServiceEmptyState (SomeService p) = SomeServiceState p (emptyServiceState p)
newtype ServiceID = ServiceID UUID
deriving (Eq, Ord, StorableUUID)
mkServiceID :: String -> ServiceID
mkServiceID = maybe (error "Invalid service ID") ServiceID . U.fromString
data ServiceInput = ServiceInput
{ svcPeer :: UnifiedIdentity
, svcPrintOp :: String -> IO ()
}
data ServiceReply s = ServiceReply (Either s (Stored s)) Bool
data ServiceHandlerState s = ServiceHandlerState
{ svcValue :: ServiceState s
, svcLocal :: Stored LocalState
}
newtype ServiceHandler s a = ServiceHandler (ReaderT ServiceInput (WriterT [ServiceReply s] (StateT (ServiceHandlerState s) (ExceptT String IO))) a)
deriving (Functor, Applicative, Monad, MonadReader ServiceInput, MonadWriter [ServiceReply s], MonadState (ServiceHandlerState s), MonadError String, MonadIO)
handleServicePacket :: Service s => Storage -> ServiceInput -> ServiceState s -> Stored s -> IO ([ServiceReply s], ServiceState s)
handleServicePacket st input svc packet = do
herb <- loadLocalStateHead st
let erb = wrappedLoad $ headRef herb
sstate = ServiceHandlerState { svcValue = svc, svcLocal = erb }
ServiceHandler handler = serviceHandler packet
(runExceptT $ flip runStateT sstate $ execWriterT $ flip runReaderT input $ handler) >>= \case
Left err -> do
svcPrintOp input $ "service failed: " ++ err
return ([], svc)
Right (rsp, sstate')
| svcLocal sstate' == svcLocal sstate -> return (rsp, svcValue sstate')
| otherwise -> replaceHead (svcLocal sstate') (Right herb) >>= \case
Left _ -> handleServicePacket st input svc packet
Right _ -> return (rsp, svcValue sstate')
svcGet :: ServiceHandler s (ServiceState s)
svcGet = gets svcValue
svcSet :: ServiceState s -> ServiceHandler s ()
svcSet x = modify $ \st -> st { svcValue = x }
svcGetLocal :: ServiceHandler s (Stored LocalState)
svcGetLocal = gets svcLocal
svcSetLocal :: Stored LocalState -> ServiceHandler s ()
svcSetLocal x = modify $ \st -> st { svcLocal = x }
svcPrint :: String -> ServiceHandler s ()
svcPrint str = liftIO . ($str) =<< asks svcPrintOp
replyPacket :: Service s => s -> ServiceHandler s ()
replyPacket x = tell [ServiceReply (Left x) True]
replyStored :: Service s => Stored s -> ServiceHandler s ()
replyStored x = tell [ServiceReply (Right x) True]
replyStoredRef :: Service s => Stored s -> ServiceHandler s ()
replyStoredRef x = tell [ServiceReply (Right x) False]
|