htalkat-0.1.1: Host.hs

-- This file is part of htalkat
-- Copyright (C) 2021 Martin Bays <mbays@sdf.org>
--
-- This program is free software: you can redistribute it and/or modify
-- it under the terms of version 3 of the GNU General Public License as
-- published by the Free Software Foundation, or any later version.
--
-- You should have received a copy of the GNU General Public License
-- along with this program.  If not, see http://www.gnu.org/licenses/.

{-# LANGUAGE Safe #-}

module Host where

import           Control.Monad (msum)
import           Data.List     (elemIndices)
import           Data.Maybe    (fromMaybe)
import           Safe          (lastMay, readMay)

data Host = Host {hostName :: String, hostPort :: Int}
    deriving (Eq,Ord,Show)

defaultTalkatPort :: Int
defaultTalkatPort = 5518

showHost :: Host -> String
showHost (Host name port) = name ++
    (if port == defaultTalkatPort then "" else ":" ++ show port)

parseHost :: String -> Maybe Host
parseHost s = msum
    [ (`Host` defaultTalkatPort) <$> decodeIPv6 s
    , do
        i <- lastMay $ elemIndices ':' s
        let (h, ':':portStr) = splitAt i s
            h' = fromMaybe h $ decodeIPv6 h
        Host h' <$> readMay portStr
    , pure $ Host s defaultTalkatPort
    ]
    where
    decodeIPv6 :: String -> Maybe String
    decodeIPv6 ('[':rest) | Just ']' <- lastMay rest = Just $ init rest
    decodeIPv6 _ = Nothing