Properties.hs

-- This module parses server.properties file,
-- the Minecraft configuration file
module Network.Loshadka.Properties
  (Properties, readProps) where

import Network (PortNumber)
import Data.Maybe
import Data.List.Split (splitOn)

data Property = MOTD String | ServerPort PortNumber | MaxPlayers Int | WhiteList Bool deriving (Eq)
type Properties = (String, PortNumber, Int, Bool)
type Key = (String, Maybe Property)

readProps :: String -> IO Properties
readProps path = do
  props <- readFile (path ++ "/server.properties")
  return $ parse props

parse :: String -> Properties
parse props = (motd, port, maxPlayers, whiteList)
  where (MOTD motd : ServerPort port : MaxPlayers maxPlayers : WhiteList whiteList : []) = fetchLines props

fetchLines :: String -> [Property]
fetchLines props = fetchProperties $ map parseLine (lines props)

parseLine :: String -> Key
parseLine prop = do
  if (head prop) == '#'
    then ("", Nothing)
    else case splitOn "=" prop of
      ["motd", value]        -> ("motd",        Just $ MOTD value)
      ["server-port", value] -> ("server-port", Just $ ServerPort $ fromIntegral (read value :: Integer))
      ["max-players", value] -> ("max-players", Just $ MaxPlayers $ read value)
      ["white-list", value]  -> ("white-list",  Just $ WhiteList $ read value)
      _                      -> ("", Nothing)

fetchProperties :: [Key] -> [Property]
fetchProperties ps = [motd, serverPort, maxPlayers, whiteList]
  where
    ns         = filter (/= ("", Nothing)) ps
    motd       = fetchProperty "motd" ns
    serverPort = fetchProperty "server-port" ns
    maxPlayers = fetchProperty "max-players" ns
    whiteList  = fetchProperty "white-list" ns

fetchProperty :: String -> [Key] -> Property
fetchProperty k ps = fromJust $ fromJust $ lookup k ps