{-# LANGUAGE OverloadedStrings #-}

module MiniJson.Greeting where

import Data.Aeson ((.:), FromJSON (parseJSON), eitherDecodeStrict', withObject)
import Data.ByteString (ByteString)
import Data.Text (Text)
import qualified Data.Text as Text

data GreetingRequest = GreetingRequest
  { name :: Text
  }

instance FromJSON GreetingRequest where
  parseJSON = withObject "GreetingRequest" (\object -> GreetingRequest <$> object .: "name")

greetFromJson :: ByteString -> Either String String
greetFromJson input = do
  request <- eitherDecodeStrict' input
  pure ("hello, " ++ Text.unpack (name request) ++ ", from aeson")