module Main where

import qualified Data.ByteString.Char8 as ByteString
import MiniJson.Greeting (greetFromJson)
import System.Environment (getArgs)
import System.Exit (die)

main :: IO ()
main = do
  args <- getArgs
  let input =
        case args of
          [] -> "{\"name\":\"learner\"}"
          firstArg : _ -> firstArg

  case greetFromJson (ByteString.pack input) of
    Left err -> die err
    Right message -> putStrLn message