module Erebos.Chatroom ( Chatroom(..), ChatroomData(..), validateChatroom, ChatroomState(..), ChatroomStateData(..), createChatroom, updateChatroomByStateData, listChatrooms, findChatroomByRoomData, findChatroomByStateData, chatroomSetSubscribe, chatroomMembers, joinChatroom, joinChatroomByStateData, joinChatroomAs, joinChatroomAsByStateData, leaveChatroom, leaveChatroomByStateData, getMessagesSinceState, ChatroomSetChange(..), watchChatrooms, ChatMessage, cmsgFrom, cmsgReplyTo, cmsgTime, cmsgText, cmsgLeave, cmsgRoom, cmsgRoomData, ChatMessageData(..), sendChatroomMessage, sendChatroomMessageByStateData, ChatroomService(..), ) where import Control.Arrow import Control.Monad import Control.Monad.Except import Control.Monad.IO.Class import Data.Bool import Data.Either import Data.Foldable import Data.Function import Data.IORef import Data.List import Data.Maybe import Data.Monoid import Data.Ord import Data.Set qualified as S import Data.Text (Text) import Data.Time import Erebos.Identity import Erebos.Object.Internal import Erebos.PubKey import Erebos.Service import Erebos.Set import Erebos.State import Erebos.Storage.Merge import Erebos.Util data ChatroomData = ChatroomData { rdPrev :: [Stored (Signed ChatroomData)] , rdName :: Maybe Text , rdDescription :: Maybe Text , rdKey :: Stored PublicKey } data Chatroom = Chatroom { roomData :: [Stored (Signed ChatroomData)] , roomName :: Maybe Text , roomDescription :: Maybe Text , roomKey :: Stored PublicKey } instance Storable ChatroomData where store' ChatroomData {..} = storeRec $ do mapM_ (storeRef "SPREV") rdPrev storeMbText "name" rdName storeMbText "description" rdDescription storeRef "key" rdKey load' = loadRec $ do rdPrev <- loadRefs "SPREV" rdName <- loadMbText "name" rdDescription <- loadMbText "description" rdKey <- loadRef "key" return ChatroomData {..} validateChatroom :: [Stored (Signed ChatroomData)] -> Except String Chatroom validateChatroom roomData = do when (null roomData) $ throwError "null data" when (not $ getAll $ walkAncestors verifySignatures roomData) $ do throwError "signature verification failed" let roomName = findPropertyFirst (rdName . fromStored . signedData) roomData roomDescription = findPropertyFirst (rdDescription . fromStored . signedData) roomData roomKey <- maybe (throwError "missing key") return $ findPropertyFirst (Just . rdKey . fromStored . signedData) roomData return Chatroom {..} where verifySignatures sdata = let rdata = fromSigned sdata required = concat [ [ rdKey rdata ] , map (rdKey . fromSigned) $ rdPrev rdata ] in All $ all (fromStored sdata `isSignedBy`) required data ChatMessageData = ChatMessageData { mdPrev :: [Stored (Signed ChatMessageData)] , mdRoom :: [Stored (Signed ChatroomData)] , mdFrom :: ComposedIdentity , mdReplyTo :: Maybe (Stored (Signed ChatMessageData)) , mdTime :: ZonedTime , mdText :: Maybe Text , mdLeave :: Bool } data ChatMessage = ChatMessage { cmsgData :: Stored (Signed ChatMessageData) } validateSingleMessage :: Stored (Signed ChatMessageData) -> Maybe ChatMessage validateSingleMessage sdata = do guard $ fromStored sdata `isSignedBy` idKeyMessage (mdFrom (fromSigned sdata)) return $ ChatMessage sdata cmsgFrom :: ChatMessage -> ComposedIdentity cmsgFrom = mdFrom . fromSigned . cmsgData cmsgReplyTo :: ChatMessage -> Maybe ChatMessage cmsgReplyTo = fmap ChatMessage . mdReplyTo . fromSigned . cmsgData cmsgTime :: ChatMessage -> ZonedTime cmsgTime = mdTime . fromSigned . cmsgData cmsgText :: ChatMessage -> Maybe Text cmsgText = mdText . fromSigned . cmsgData cmsgLeave :: ChatMessage -> Bool cmsgLeave = mdLeave . fromSigned . cmsgData cmsgRoom :: ChatMessage -> Maybe Chatroom cmsgRoom = either (const Nothing) Just . runExcept . validateChatroom . cmsgRoomData cmsgRoomData :: ChatMessage -> [ Stored (Signed ChatroomData) ] cmsgRoomData = concat . findProperty ((\case [] -> Nothing; xs -> Just xs) . mdRoom . fromStored . signedData) . (: []) . cmsgData instance Storable ChatMessageData where store' ChatMessageData {..} = storeRec $ do mapM_ (storeRef "SPREV") mdPrev mapM_ (storeRef "room") mdRoom mapM_ (storeRef "from") $ idExtDataF mdFrom storeMbRef "reply-to" mdReplyTo storeDate "time" mdTime storeMbText "text" mdText when mdLeave $ storeEmpty "leave" load' = loadRec $ do mdPrev <- loadRefs "SPREV" mdRoom <- loadRefs "room" mdFrom <- loadIdentity "from" mdReplyTo <- loadMbRef "reply-to" mdTime <- loadDate "time" mdText <- loadMbText "text" mdLeave <- isJust <$> loadMbEmpty "leave" return ChatMessageData {..} threadToListSince :: [ Stored (Signed ChatMessageData) ] -> [ Stored (Signed ChatMessageData) ] -> [ ChatMessage ] threadToListSince since thread = helper (S.fromList since) thread where helper :: S.Set (Stored (Signed ChatMessageData)) -> [Stored (Signed ChatMessageData)] -> [ChatMessage] helper seen msgs | msg : msgs' <- filter (`S.notMember` seen) $ reverse $ sortBy (comparing cmpView) msgs = maybe id (:) (validateSingleMessage msg) $ helper (S.insert msg seen) (msgs' ++ mdPrev (fromSigned msg)) | otherwise = [] cmpView msg = (zonedTimeToUTC $ mdTime $ fromSigned msg, msg) sendChatroomMessage :: (MonadStorage m, MonadHead LocalState m, MonadError String m) => ChatroomState -> Text -> m () sendChatroomMessage rstate msg = sendChatroomMessageByStateData (head $ roomStateData rstate) msg sendChatroomMessageByStateData :: (MonadStorage m, MonadHead LocalState m, MonadError String m) => Stored ChatroomStateData -> Text -> m () sendChatroomMessageByStateData lookupData msg = sendRawChatroomMessageByStateData lookupData Nothing Nothing (Just msg) False sendRawChatroomMessageByStateData :: (MonadStorage m, MonadHead LocalState m, MonadError String m) => Stored ChatroomStateData -> Maybe UnifiedIdentity -> Maybe (Stored (Signed ChatMessageData)) -> Maybe Text -> Bool -> m () sendRawChatroomMessageByStateData lookupData mbIdentity mdReplyTo mdText mdLeave = void $ findAndUpdateChatroomState $ \cstate -> do guard $ any (lookupData `precedesOrEquals`) $ roomStateData cstate Just $ do mdFrom <- finalOwner <$> if | Just identity <- mbIdentity -> return identity | Just identity <- roomStateIdentity cstate -> return identity | otherwise -> localIdentity . fromStored <$> getLocalHead secret <- loadKey $ idKeyMessage mdFrom mdTime <- liftIO getZonedTime let mdPrev = roomStateMessageData cstate mdRoom = if null (roomStateMessageData cstate) then maybe [] roomData (roomStateRoom cstate) else [] mdata <- mstore =<< sign secret =<< mstore ChatMessageData {..} mergeSorted . (:[]) <$> mstore ChatroomStateData { rsdPrev = roomStateData cstate , rsdRoom = [] , rsdSubscribe = Just (not mdLeave) , rsdIdentity = mbIdentity , rsdMessages = [ mdata ] } data ChatroomStateData = ChatroomStateData { rsdPrev :: [Stored ChatroomStateData] , rsdRoom :: [Stored (Signed ChatroomData)] , rsdSubscribe :: Maybe Bool , rsdIdentity :: Maybe UnifiedIdentity , rsdMessages :: [Stored (Signed ChatMessageData)] } data ChatroomState = ChatroomState { roomStateData :: [Stored ChatroomStateData] , roomStateRoom :: Maybe Chatroom , roomStateMessageData :: [Stored (Signed ChatMessageData)] , roomStateSubscribe :: Bool , roomStateIdentity :: Maybe UnifiedIdentity , roomStateMessages :: [ChatMessage] } instance Storable ChatroomStateData where store' ChatroomStateData {..} = storeRec $ do forM_ rsdPrev $ storeRef "PREV" forM_ rsdRoom $ storeRef "room" forM_ rsdSubscribe $ storeInt "subscribe" . bool @Int 0 1 forM_ rsdIdentity $ storeRef "id" . idExtData forM_ rsdMessages $ storeRef "msg" load' = loadRec $ do rsdPrev <- loadRefs "PREV" rsdRoom <- loadRefs "room" rsdSubscribe <- fmap ((/=) @Int 0) <$> loadMbInt "subscribe" rsdIdentity <- loadMbUnifiedIdentity "id" rsdMessages <- loadRefs "msg" return ChatroomStateData {..} instance Mergeable ChatroomState where type Component ChatroomState = ChatroomStateData mergeSorted roomStateData = let roomStateRoom = either (const Nothing) Just $ runExcept $ validateChatroom $ concat $ findProperty ((\case [] -> Nothing; xs -> Just xs) . rsdRoom) roomStateData roomStateMessageData = filterAncestors $ concat $ flip findProperty roomStateData $ \case ChatroomStateData {..} | null rsdMessages -> Nothing | otherwise -> Just rsdMessages roomStateSubscribe = fromMaybe False $ findPropertyFirst rsdSubscribe roomStateData roomStateIdentity = findPropertyFirst rsdIdentity roomStateData roomStateMessages = threadToListSince [] $ concatMap (rsdMessages . fromStored) roomStateData in ChatroomState {..} toComponents = roomStateData instance SharedType (Set ChatroomState) where sharedTypeID _ = mkSharedTypeID "7bc71cbf-bc43-42b1-b413-d3a2c9a2aae0" createChatroom :: (MonadStorage m, MonadHead LocalState m, MonadIO m, MonadError String m) => Maybe Text -> Maybe Text -> m ChatroomState createChatroom rdName rdDescription = do (secret, rdKey) <- liftIO . generateKeys =<< getStorage let rdPrev = [] rdata <- mstore =<< sign secret =<< mstore ChatroomData {..} cstate <- mergeSorted . (:[]) <$> mstore ChatroomStateData { rsdPrev = [] , rsdRoom = [ rdata ] , rsdSubscribe = Just True , rsdIdentity = Nothing , rsdMessages = [] } updateLocalHead $ updateSharedState $ \rooms -> do st <- getStorage (, cstate) <$> storeSetAdd st cstate rooms findAndUpdateChatroomState :: (MonadStorage m, MonadHead LocalState m) => (ChatroomState -> Maybe (m ChatroomState)) -> m (Maybe ChatroomState) findAndUpdateChatroomState f = do updateLocalHead $ updateSharedState $ \roomSet -> do let roomList = fromSetBy (comparing $ roomName <=< roomStateRoom) roomSet case catMaybes $ map (\x -> (x,) <$> f x) roomList of ((orig, act) : _) -> do upd <- act if roomStateData orig /= roomStateData upd then do st <- getStorage roomSet' <- storeSetAdd st upd roomSet return (roomSet', Just upd) else do return (roomSet, Just upd) [] -> return (roomSet, Nothing) updateChatroomByStateData :: (MonadStorage m, MonadHead LocalState m, MonadError String m) => Stored ChatroomStateData -> Maybe Text -> Maybe Text -> m (Maybe ChatroomState) updateChatroomByStateData lookupData newName newDesc = findAndUpdateChatroomState $ \cstate -> do guard $ any (lookupData `precedesOrEquals`) $ roomStateData cstate room <- roomStateRoom cstate Just $ do secret <- loadKey $ roomKey room rdata <- mstore =<< sign secret =<< mstore ChatroomData { rdPrev = roomData room , rdName = newName , rdDescription = newDesc , rdKey = roomKey room } mergeSorted . (:[]) <$> mstore ChatroomStateData { rsdPrev = roomStateData cstate , rsdRoom = [ rdata ] , rsdSubscribe = Just True , rsdIdentity = Nothing , rsdMessages = [] } listChatrooms :: MonadHead LocalState m => m [ChatroomState] listChatrooms = fromSetBy (comparing $ roomName <=< roomStateRoom) . lookupSharedValue . lsShared . fromStored <$> getLocalHead findChatroom :: MonadHead LocalState m => (ChatroomState -> Bool) -> m (Maybe ChatroomState) findChatroom p = do list <- map snd . chatroomSetToList . lookupSharedValue . lsShared . fromStored <$> getLocalHead return $ find p list findChatroomByRoomData :: MonadHead LocalState m => Stored (Signed ChatroomData) -> m (Maybe ChatroomState) findChatroomByRoomData cdata = findChatroom $ maybe False (any (cdata `precedesOrEquals`) . roomData) . roomStateRoom findChatroomByStateData :: MonadHead LocalState m => Stored ChatroomStateData -> m (Maybe ChatroomState) findChatroomByStateData cdata = findChatroom $ any (cdata `precedesOrEquals`) . roomStateData chatroomSetSubscribe :: (MonadStorage m, MonadHead LocalState m, MonadError String m) => Stored ChatroomStateData -> Bool -> m () chatroomSetSubscribe lookupData subscribe = void $ findAndUpdateChatroomState $ \cstate -> do guard $ any (lookupData `precedesOrEquals`) $ roomStateData cstate Just $ do mergeSorted . (:[]) <$> mstore ChatroomStateData { rsdPrev = roomStateData cstate , rsdRoom = [] , rsdSubscribe = Just subscribe , rsdIdentity = Nothing , rsdMessages = [] } chatroomMembers :: ChatroomState -> [ ComposedIdentity ] chatroomMembers ChatroomState {..} = map (mdFrom . fromSigned . head) $ filter (any $ not . mdLeave . fromSigned) $ -- keep only users that hasn't left map (filterAncestors . map snd) $ -- gather message data per each identity and filter ancestors groupBy ((==) `on` fst) $ -- group on identity root sortBy (comparing fst) $ -- sort by first root of identity data map (\x -> ( head . filterAncestors . concatMap storedRoots . idDataF . mdFrom . fromSigned $ x, x )) $ toList $ ancestors $ roomStateMessageData joinChatroom :: (MonadStorage m, MonadHead LocalState m, MonadError String m) => ChatroomState -> m () joinChatroom rstate = joinChatroomByStateData (head $ roomStateData rstate) joinChatroomByStateData :: (MonadStorage m, MonadHead LocalState m, MonadError String m) => Stored ChatroomStateData -> m () joinChatroomByStateData lookupData = sendRawChatroomMessageByStateData lookupData Nothing Nothing Nothing False joinChatroomAs :: (MonadStorage m, MonadHead LocalState m, MonadError String m) => UnifiedIdentity -> ChatroomState -> m () joinChatroomAs identity rstate = joinChatroomAsByStateData identity (head $ roomStateData rstate) joinChatroomAsByStateData :: (MonadStorage m, MonadHead LocalState m, MonadError String m) => UnifiedIdentity -> Stored ChatroomStateData -> m () joinChatroomAsByStateData identity lookupData = sendRawChatroomMessageByStateData lookupData (Just identity) Nothing Nothing False leaveChatroom :: (MonadStorage m, MonadHead LocalState m, MonadError String m) => ChatroomState -> m () leaveChatroom rstate = leaveChatroomByStateData (head $ roomStateData rstate) leaveChatroomByStateData :: (MonadStorage m, MonadHead LocalState m, MonadError String m) => Stored ChatroomStateData -> m () leaveChatroomByStateData lookupData = sendRawChatroomMessageByStateData lookupData Nothing Nothing Nothing True getMessagesSinceState :: ChatroomState -> ChatroomState -> [ChatMessage] getMessagesSinceState cur old = threadToListSince (roomStateMessageData old) (roomStateMessageData cur) data ChatroomSetChange = AddedChatroom ChatroomState | RemovedChatroom ChatroomState | UpdatedChatroom ChatroomState ChatroomState watchChatrooms :: MonadIO m => Head LocalState -> (Set ChatroomState -> Maybe [ChatroomSetChange] -> IO ()) -> m WatchedHead watchChatrooms h f = liftIO $ do lastVar <- newIORef Nothing watchHeadWith h (lookupSharedValue . lsShared . headObject) $ \cur -> do let curList = chatroomSetToList cur mbLast <- readIORef lastVar writeIORef lastVar $ Just curList f cur $ do lastList <- mbLast return $ makeChatroomDiff lastList curList chatroomSetToList :: Set ChatroomState -> [(Stored ChatroomStateData, ChatroomState)] chatroomSetToList = map (cmp &&& id) . fromSetBy (comparing cmp) where cmp :: ChatroomState -> Stored ChatroomStateData cmp = head . filterAncestors . concatMap storedRoots . toComponents makeChatroomDiff :: [(Stored ChatroomStateData, ChatroomState)] -> [(Stored ChatroomStateData, ChatroomState)] -> [ChatroomSetChange] makeChatroomDiff (x@(cx, vx) : xs) (y@(cy, vy) : ys) | cx < cy = RemovedChatroom vx : makeChatroomDiff xs (y : ys) | cx > cy = AddedChatroom vy : makeChatroomDiff (x : xs) ys | roomStateData vx /= roomStateData vy = UpdatedChatroom vx vy : makeChatroomDiff xs ys | otherwise = makeChatroomDiff xs ys makeChatroomDiff xs [] = map (RemovedChatroom . snd) xs makeChatroomDiff [] ys = map (AddedChatroom . snd) ys data ChatroomService = ChatroomService { chatRoomQuery :: Bool , chatRoomInfo :: [Stored (Signed ChatroomData)] , chatRoomSubscribe :: [Stored (Signed ChatroomData)] , chatRoomUnsubscribe :: [Stored (Signed ChatroomData)] , chatRoomMessage :: [Stored (Signed ChatMessageData)] } deriving (Eq) emptyPacket :: ChatroomService emptyPacket = ChatroomService { chatRoomQuery = False , chatRoomInfo = [] , chatRoomSubscribe = [] , chatRoomUnsubscribe = [] , chatRoomMessage = [] } instance Storable ChatroomService where store' ChatroomService {..} = storeRec $ do when chatRoomQuery $ storeEmpty "room-query" forM_ chatRoomInfo $ storeRef "room-info" forM_ chatRoomSubscribe $ storeRef "room-subscribe" forM_ chatRoomUnsubscribe $ storeRef "room-unsubscribe" forM_ chatRoomMessage $ storeRef "room-message" load' = loadRec $ do chatRoomQuery <- isJust <$> loadMbEmpty "room-query" chatRoomInfo <- loadRefs "room-info" chatRoomSubscribe <- loadRefs "room-subscribe" chatRoomUnsubscribe <- loadRefs "room-unsubscribe" chatRoomMessage <- loadRefs "room-message" return ChatroomService {..} data PeerState = PeerState { psSendRoomUpdates :: Bool , psLastList :: [(Stored ChatroomStateData, ChatroomState)] , psSubscribedTo :: [ Stored (Signed ChatroomData) ] -- least root for each room } instance Service ChatroomService where serviceID _ = mkServiceID "627657ae-3e39-468a-8381-353395ef4386" type ServiceState ChatroomService = PeerState emptyServiceState _ = PeerState { psSendRoomUpdates = False , psLastList = [] , psSubscribedTo = [] } serviceHandler spacket = do let ChatroomService {..} = fromStored spacket previouslyUpdated <- psSendRoomUpdates <$> svcGet svcModify $ \s -> s { psSendRoomUpdates = True } when (not previouslyUpdated) $ do syncChatroomsToPeer . lookupSharedValue . lsShared . fromStored =<< getLocalHead when chatRoomQuery $ do rooms <- listChatrooms replyPacket emptyPacket { chatRoomInfo = concatMap roomData $ catMaybes $ map roomStateRoom rooms } when (not $ null chatRoomInfo) $ do updateLocalHead_ $ updateSharedState_ $ \roomSet -> do let rooms = fromSetBy (comparing $ roomName <=< roomStateRoom) roomSet upd set (roomInfo :: Stored (Signed ChatroomData)) = do let currentRoots = storedRoots roomInfo isCurrentRoom = any ((`intersectsSorted` currentRoots) . storedRoots) . maybe [] roomData . roomStateRoom let prev = concatMap roomStateData $ filter isCurrentRoom rooms prevRoom = filterAncestors $ concat $ findProperty ((\case [] -> Nothing; xs -> Just xs) . rsdRoom) prev room = filterAncestors $ (roomInfo : ) prevRoom -- update local state only if we got roomInfo not present there if roomInfo `notElem` prevRoom && roomInfo `elem` room then do sdata <- mstore ChatroomStateData { rsdPrev = prev , rsdRoom = room , rsdSubscribe = Nothing , rsdIdentity = Nothing , rsdMessages = [] } storeSetAddComponent sdata set else return set foldM upd roomSet chatRoomInfo forM_ chatRoomSubscribe $ \subscribeData -> do mbRoomState <- findChatroomByRoomData subscribeData forM_ mbRoomState $ \roomState -> forM (roomStateRoom roomState) $ \room -> do let leastRoot = head . filterAncestors . concatMap storedRoots . roomData $ room svcModify $ \ps -> ps { psSubscribedTo = leastRoot : psSubscribedTo ps } replyPacket emptyPacket { chatRoomMessage = roomStateMessageData roomState } forM_ chatRoomUnsubscribe $ \unsubscribeData -> do mbRoomState <- findChatroomByRoomData unsubscribeData forM_ (mbRoomState >>= roomStateRoom) $ \room -> do let leastRoot = head . filterAncestors . concatMap storedRoots . roomData $ room svcModify $ \ps -> ps { psSubscribedTo = filter (/= leastRoot) (psSubscribedTo ps) } when (not (null chatRoomMessage)) $ do updateLocalHead_ $ updateSharedState_ $ \roomSet -> do let rooms = fromSetBy (comparing $ roomName <=< roomStateRoom) roomSet upd set (msgData :: Stored (Signed ChatMessageData)) | Just msg <- validateSingleMessage msgData = do let roomInfo = cmsgRoomData msg currentRoots = filterAncestors $ concatMap storedRoots roomInfo isCurrentRoom = any ((`intersectsSorted` currentRoots) . storedRoots) . maybe [] roomData . roomStateRoom let prevData = concatMap roomStateData $ filter isCurrentRoom rooms prev = mergeSorted prevData prevMessages = roomStateMessageData prev messages = filterAncestors $ msgData : prevMessages -- update local state only if subscribed and we got some new messages if roomStateSubscribe prev && messages /= prevMessages then do sdata <- mstore ChatroomStateData { rsdPrev = prevData , rsdRoom = [] , rsdSubscribe = Nothing , rsdIdentity = Nothing , rsdMessages = messages } storeSetAddComponent sdata set else return set | otherwise = return set foldM upd roomSet chatRoomMessage serviceNewPeer = do replyPacket emptyPacket { chatRoomQuery = True } serviceStorageWatchers _ = (:[]) $ SomeStorageWatcher (lookupSharedValue . lsShared . fromStored) syncChatroomsToPeer syncChatroomsToPeer :: Set ChatroomState -> ServiceHandler ChatroomService () syncChatroomsToPeer set = do ps@PeerState {..} <- svcGet when psSendRoomUpdates $ do let curList = chatroomSetToList set diff = makeChatroomDiff psLastList curList roomUpdates <- fmap (concat . catMaybes) $ forM diff $ return . \case AddedChatroom room -> roomData <$> roomStateRoom room RemovedChatroom {} -> Nothing UpdatedChatroom oldroom room | roomStateData oldroom /= roomStateData room -> roomData <$> roomStateRoom room | otherwise -> Nothing (subscribe, unsubscribe) <- fmap (partitionEithers . concat . catMaybes) $ forM diff $ return . \case AddedChatroom room | roomStateSubscribe room -> map Left . roomData <$> roomStateRoom room RemovedChatroom oldroom | roomStateSubscribe oldroom -> map Right . roomData <$> roomStateRoom oldroom UpdatedChatroom oldroom room | roomStateSubscribe oldroom /= roomStateSubscribe room -> map (if roomStateSubscribe room then Left else Right) . roomData <$> roomStateRoom room _ -> Nothing messages <- fmap concat $ do let leastRootFor = head . filterAncestors . concatMap storedRoots . roomData forM diff $ return . \case AddedChatroom rstate | Just room <- roomStateRoom rstate , leastRootFor room `elem` psSubscribedTo -> roomStateMessageData rstate UpdatedChatroom oldstate rstate | Just room <- roomStateRoom rstate , leastRootFor room `elem` psSubscribedTo , roomStateMessageData oldstate /= roomStateMessageData rstate -> roomStateMessageData rstate _ -> [] let packet = emptyPacket { chatRoomInfo = roomUpdates , chatRoomSubscribe = subscribe , chatRoomUnsubscribe = unsubscribe , chatRoomMessage = messages } when (packet /= emptyPacket) $ do replyPacket packet svcSet $ ps { psLastList = curList }