module LogParser where
import Numeric ()
data MessageType = Info
                 | Warning
                 | Error Int
                 deriving (Show,Eq)

type TimeStamp = Int

data LogMessage = LogMessage MessageType TimeStamp String | Unknown String
                deriving (Show,Eq)


parseMessage :: String -> LogMessage
parseMessage st = case words st of
  (errIdent:errCode:timeStamp:msgWords) | Just timeStampInt <- readMaybe timeStamp , Just errCodeInt <- readMaybe errCode, errIdent == "E" ->
    LogMessage (Error errCodeInt) timeStampInt (concat msgWords)
  (msgIdent:timeStamp:msgWords) | Just timeStampInt <- readMaybe timeStamp -> case msgIdent of
    "I" -> LogMessage Info timeStampInt (concat msgWords)
    "W" -> LogMessage Warning timeStampInt (concat msgWords)
    _   -> Unknown st
  _ -> Unknown st


readMaybe :: (Read a) => String -> Maybe a
readMaybe s = case reads s of
  [(x,"")] -> Just x
  _ -> Nothing