1 module EngineInteraction where

     2 

     3 import qualified Data.Set as Set

     4 import qualified Data.List as List

     5 import Control.Monad

     6 import qualified Codec.Binary.Base64 as Base64

     7 import qualified Data.ByteString.Char8 as B

     8 import qualified Data.ByteString as BW

     9 

    10 

    11 

    12 toEngineMsg :: B.ByteString -> B.ByteString

    13 toEngineMsg msg = B.pack $ Base64.encode (fromIntegral (BW.length msg) : BW.unpack msg)

    14 

    15 

    16 fromEngineMsg :: B.ByteString -> Maybe B.ByteString

    17 fromEngineMsg msg = liftM BW.pack (Base64.decode (B.unpack msg) >>= removeLength)

    18     where

    19         removeLength (x:xs) = if length xs == fromIntegral x then Just xs else Nothing

    20         removeLength _ = Nothing

    21 

    22 

    23 checkNetCmd :: B.ByteString -> (Bool, Bool)

    24 checkNetCmd msg = check decoded

    25     where

    26         decoded = fromEngineMsg msg

    27         check Nothing = (False, False)

    28         check (Just ms) | B.length ms > 0 = let m = B.head ms in (m `Set.member` legalMessages, m == '+')

    29                         | otherwise        = (False, False)

    30         legalMessages = Set.fromList $ "M#+LlRrUuDdZzAaSjJ,sFNpPwtghbc12345" ++ slotMessages

    31         slotMessages = "\128\129\130\131\132\133\134\135\136\137\138"

    32