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{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE MultiWayIf #-}
module Server where
import Prelude hiding (Word)
import Control.Concurrent.STM
import Control.Monad (void)
import Control.Monad.Loops (iterateUntilM)
import Data.List (delete)
import qualified Data.Map.Strict as Map
import Data.Map.Strict (Map)
import System.Random
import Types
data ServerIn = ServerIn ServerIn' (TMVar [ServerOut])
data ServerIn'
= IAnon Cmd
| IAs User Cmd
deriving (Show)
data ServerOut
= OResponse Response
| OLogin User
| OLogout
| ODisconnect
deriving (Show)
data ClientAction
= CAResponse Response
| CAPush Push
| CADisconnect
deriving (Show)
data ClientState
= CSDisconnected
| CSAnon
| CSUser User
| CSVersionWait
deriving (Show)
clientGate :: TQueue ServerIn -> TQueue (Maybe Cmd) -> TQueue ClientAction -> IO ()
clientGate server clientIn clientOut =
void $ iterateUntilM (\case CSDisconnected -> True ; _ -> False) body CSVersionWait
where
body state = do
atomically (readTQueue clientIn) >>= \case
Nothing -> return CSDisconnected
Just (CVersion (Word "3")) -> do
atomically (writeTQueue clientOut (CAResponse ROk))
case state of
CSVersionWait -> return CSAnon
_ -> return state
Just (CVersion _) -> do
atomically (writeTQueue clientOut (CAResponse (RError "Version not supported")))
return CSVersionWait
Just cmd -> do
let msg = case state of CSAnon -> IAnon cmd
CSUser u -> IAs u cmd
_ -> error "impossible"
resVar <- newEmptyTMVarIO
atomically (writeTQueue server (ServerIn msg resVar))
outs <- atomically (readTMVar resVar)
loopM outs state $ curry $ \case
(CSDisconnected, _) -> return CSDisconnected
(state', OResponse res) -> do
atomically (writeTQueue clientOut (CAResponse res))
return state'
(_, OLogin u) -> return (CSUser u)
(_, OLogout) -> return CSAnon
(_, ODisconnect) -> return CSDisconnected
data ServerState
= ServerState { ssRooms :: Map Room RoomState
, ssUsers :: Map User UserData
, ssRNG :: StdGen }
deriving (Show)
data RoomState
= RoomState { rsHistory :: Map Id HistoryItem
, rsMembers :: [User] }
deriving (Show)
data UserData
= UserData { udPassword :: Line }
deriving (Show)
data HistoryItem
= HIMsg { hiId :: Id
, hiTimestamp :: Int
, hiUser :: User
, hiReplyId :: Maybe Id
, hiLine :: Line }
deriving (Show)
initialServerState :: ServerState
initialServerState =
ServerState { ssRooms = mempty
, ssUsers = mempty
, ssRNG = mkStdGen 1234 }
emptyRoomState :: RoomState
emptyRoomState =
RoomState { rsHistory = mempty
, rsMembers = [] }
serverHandleEvent :: ServerState -> ServerIn' -> (ServerState, [ServerOut])
serverHandleEvent state = \case
IAnon (CRegister u p)
| u `Map.member` ssUsers state -> (state, [OResponse (RError "User already exists")])
| otherwise -> (state { ssUsers = Map.insert u (UserData p) (ssUsers state) }
,[OResponse ROk])
IAnon (CLogin u p)
| Just ud <- Map.lookup u (ssUsers state)
, p == udPassword ud
-> (state, [OResponse ROk, OLogin u])
| otherwise -> (state, [OResponse (RError "Invalid password")])
IAnon _ -> (state, [OResponse (RError "Not logged in")])
IAs user cmd -> case cmd of
CChangePassword p ->
(state { ssUsers = Map.adjust (\ud -> ud { udPassword = p }) user (ssUsers state) }
,[OResponse ROk])
CLogout -> (state, [OResponse ROk, OLogout])
CListRooms -> (state, [OResponse (RList (map fromRoom (Map.keys (ssRooms state))))])
CListMembers r
| Just (RoomState { rsMembers = mbs }) <- Map.lookup r (ssRooms state)
, user `elem` mbs
-> (state, [OResponse (RList (map fromUser mbs))])
| otherwise
-> (state, [OResponse (RError "Room not found")])
CCreateRoom ->
let (rng', roomid) = genRoomId (ssRNG state)
in (state { ssRooms = Map.insert roomid emptyRoomState (ssRooms state)
, ssRNG = rng' }
,[OResponse (RName (fromRoom roomid))])
CLeaveRoom r
| Just rs@(RoomState { rsMembers = mbs }) <- Map.lookup r (ssRooms state)
, user `elem` mbs
-> (state { ssRooms = Map.insert r (rs { rsMembers = delete user mbs }) (ssRooms state) }
,[OResponse ROk])
| otherwise
-> (state, [OResponse (RError "Not in that room")])
CInvite r u
| Just (RoomState { rsMembers = mbs }) <- Map.lookup r (ssRooms state)
, user `elem` mbs
-> if | user `Map.notMember` ssUsers state -> (state, [OResponse (RError "User not found")])
| user `elem` mbs -> (state, [OResponse (RError "User already in room")])
| otherwise ->
(state { ssRooms = Map.adjust (\rs -> rs { rsMembers = u : rsMembers rs })
r (ssRooms state) }
,[OResponse ROk, push_to_u_something, broadcast_something])
| otherwise
-> (state, [OResponse (RError "Not in that room")])
loopM :: Monad m => [a] -> s -> (s -> a -> m s) -> m s
loopM [] s _ = return s
loopM (x:xs) s f = f s x >>= \s' -> loopM xs s' f
genRoomId :: RandomGen g => g -> (g, Room)
genRoomId gen =
let (is, gen') = uniformRN 8 (0, 2 * 26) gen
in (gen', Room (Word (map ((['a'..'z'] ++ ['A'..'Z']) !!) is)))
where
uniformRN :: (RandomGen g, UniformRange a) => Int -> (a, a) -> g -> ([a], g)
uniformRN 0 r g = let (x, g') = uniformR r g
in ([x], g')
uniformRN n r g = let (x, g') = uniformR r g
(xs, g'') = uniformRN (n-1) r g'
in (x:xs, g'')
|
