module DDNS.Utils
    ( trim
    , getInputLine'
    , getInputLineWithDefault
    , readInputLine'
    , readInputLineWithDefault
    )
    where

import           Control.Monad
import           System.Console.Haskeline


trim :: Maybe String -> Maybe String
trim Nothing   = Nothing
trim (Just xs) = case trimTail $ trimHead xs of
                   "" -> Nothing
                   ys -> Just ys
    where
      trimHead []       = []
      trimHead (' ':ys) = trimHead ys
      trimHead ys       = ys

      trimTail = reverse . trimHead . reverse

getInputLine' :: MonadException m => String -> InputT m String
getInputLine' prompt
    = do ret <- getInputLine prompt
         case trim ret of
           Just ret' -> return ret'
           Nothing   -> fail "No input"

getInputLineWithDefault :: MonadException m => String -> String -> InputT m String
getInputLineWithDefault prompt defaultStr
    = do ret <- getInputLine prompt
         case trim ret of
           Just ret' -> return ret'
           Nothing   -> return defaultStr


readInputLine' :: (MonadException m, Read r) => String -> InputT m r
readInputLine' = liftM read . getInputLine'

readInputLineWithDefault :: (MonadException m, Read r) => String -> r -> InputT m r
readInputLineWithDefault prompt defaultValue
    = do ret <- getInputLine prompt
         case trim ret of
           Just ret' -> return $ read ret'
           Nothing   -> return defaultValue