ServerState.hs

module Network.Socketson.ServerState where

-- mvar:
-- import Control.Concurrent.MVar
-- random numbers:
import Crypto.Random.DRBG

-- | The inner state of the `socketson` service.
data ServerState =
  ServerState { storePath :: FilePath
              -- ^ path to the session data storage
              , maxClients :: Int
              -- ^ number of maximal allowed clients
              , connectedClients :: Int
              -- ^ number of connected clients
              , randomGen :: CtrDRBG
              -- ^ the random generator, used for generating session keys.
              }

{-| Opens a new server state with given parameters. Initializes a fresh random number generator to generate session keys.

    newState pathToSessionStore maxClients
-}
newState :: FilePath -> Int -> IO ServerState
newState fp maxcl =
  do --plock <- newMVar fp
     g <- newGenIO :: IO CtrDRBG
     return (ServerState fp maxcl 0 g)

------
-- utility

-- | Increments the number of connected clients.
incClients :: ServerState -> ServerState
incClients st = st { connectedClients = connectedClients st + 1 }

-- | Decrements the number of connected clients.
decClients :: ServerState -> ServerState
decClients st = st { connectedClients = connectedClients st - 1 }

-- | Checks if there is still capacity for clients to connect.
existsCapacity :: ServerState -> Bool
existsCapacity st = (maxClients st - connectedClients st) > 0