{-# LANGUAGE DataKinds       #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE TypeOperators   #-}
module Main (main) where

import           Prelude ()
import           Prelude.Compat

import           Data.Aeson.TH
import           Data.Char
                 (toLower)
import           Data.Maybe
                 (fromMaybe)
import           Network.Wai
                 (Application)
import           Servant
import           Servant.Yaml
import           System.Environment
                 (getArgs, lookupEnv)
import           Text.Read
                 (readMaybe)

import qualified Network.Wai.Handler.Warp as Warp

data Foo = Foo
    { _fooFoo :: Int
    , _fooBar :: String
    }
    deriving (Eq, Show)

$(deriveJSON defaultOptions{fieldLabelModifier = map toLower . drop 4} ''Foo)

type API = "foo" :> ReqBody '[JSON, YAML] Foo :> Post '[JSON, YAML] Foo
      :<|> Get '[YAML, JSON] Foo

api :: Proxy API
api = Proxy

server :: Server API
server = pure :<|>  pure (Foo 42 "Yaml!")

app :: Application
app = serve api server

main :: IO ()
main = do
    args <- getArgs
    case args of
        ("run":_) -> do
            port <- fromMaybe 8000 . (>>= readMaybe) <$> lookupEnv "PORT"
            Warp.run port app
        _ -> putStrLn "To run, pass run argument"