module SocketActivation.GetByName where

import Control.Applicative (Applicative ((<*>)), (<$>))
import Control.Monad (Monad (return, (>>=)))
import Control.Monad.IO.Class (MonadIO (liftIO))
import Data.Either (Either)
import Data.Function ((.))
import Data.List (zip)
import Data.Map (Map)
import Data.Maybe (maybe)
import System.IO (IO)

import qualified Data.Map as Map

import SocketActivation.Concepts
    (Socket, Fd, Error (NoSuchName), Names (namesList), Name)
import SocketActivation.Env (getEnv')
import SocketActivation.GetFileDescriptors (getFileDescriptorList)
import SocketActivation.GetSockets (getSocketList, fdSocket)
import SocketActivation.IO (IO' (IO', run), throwError)

getNameList :: IO (Either Error [Name])
getNameList = run (getNames >>= unwrap)
  where
    getNames = IO' (getEnv' @Names)
    unwrap = return . namesList

getFileDescriptorMap :: IO (Either Error (Map Name Fd))
getFileDescriptorMap = run (entries >>= toMap)
  where
    entries = zip <$> keys <*> values
    keys = IO' getNameList
    values = IO' getFileDescriptorList
    toMap = return . Map.fromList

getSocketMap :: IO (Either Error (Map Name Socket))
getSocketMap = run (entries >>= toMap)
  where
    entries = zip <$> keys <*> values
    keys = IO' getNameList
    values = IO' getSocketList
    toMap = return . Map.fromList

getSocketByName :: Name -> IO (Either Error Socket)
getSocketByName name = run (getMap >>= findFd >>= convertToSocket)
  where
    getMap = IO' getFileDescriptorMap
    findFd = maybe (throwError (NoSuchName name)) return . Map.lookup name
    convertToSocket = liftIO . fdSocket