module Main where

import Control.Applicative ((<$>), (<*>))
import Happstack.Server (ServerPart, badRequest, nullConf, ok, simpleHTTP)
import Happstack.Server.RqData (RqData, checkRq, getDataFn, look, lookRead)

inRange :: (Show a, Ord a) => a -> a -> a -> Either String a
inRange lower upper a
    | lower <= a && a <= upper = Right a
    | otherwise =
        Left (show a ++ " is not between " ++ show lower ++ " and " ++ show upper)

oneToTenPart :: ServerPart String
oneToTenPart =
    do r <- getDataFn (lookRead "i" `checkRq` (inRange (1 :: Int) 10))
       case r of
         (Left e) ->
             badRequest $ unlines e
         (Right i) ->
             ok $ "You picked: " ++ show i

main :: IO ()
main = simpleHTTP nullConf $ oneToTenPart