{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeOperators #-}

import Data.Aeson
import Data.Proxy
import Data.Text
import GHC.Generics
import Network.Wai
import Network.Wai.Handler.Warp
import Prelude.Compat
import Prelude ()

import Servant
import Servant.Server.Generic ()

-- * Example

-- | A greet message data type
newtype Greet = Greet {_msg :: Text}
  deriving (Generic, Show)

instance FromJSON Greet

instance ToJSON Greet

-- API specification
type TestApi =
  -- GET /hello/:name?capital={true, false}  returns a Greet as JSON
  "hello" :> Capture "name" Text :> QueryParam "capital" Bool :> Get '[JSON] Greet
    -- POST /greet with a Greet as JSON in the request body,
    --             returns a Greet as JSON
    :<|> "greet" :> ReqBody '[JSON] Greet :> Post '[JSON] Greet
    -- DELETE /greet/:greetid
    :<|> "greet" :> Capture "greetid" Text :> Delete '[JSON] NoContent
    :<|> NamedRoutes OtherRoutes

data OtherRoutes mode = OtherRoutes
  { version :: mode :- Get '[JSON] Int
  , bye :: mode :- "bye" :> Capture "name" Text :> Get '[JSON] Text
  }
  deriving (Generic)

testApi :: Proxy TestApi
testApi = Proxy

-- Server-side handlers.
--
-- There's one handler per endpoint, which, just like in the type
-- that represents the API, are glued together using :<|>.
--
-- Each handler runs in the 'Handler' monad.
server :: Server TestApi
server = helloH :<|> postGreetH :<|> deleteGreetH :<|> otherRoutes
  where
    otherRoutes = OtherRoutes{..}

    bye name = pure $ "Bye, " <> name <> " !"
    version = pure 42

    helloH name Nothing = helloH name (Just False)
    helloH name (Just False) = pure . Greet $ "Hello, " <> name
    helloH name (Just True) = pure . Greet . toUpper $ "Hello, " <> name

    postGreetH = pure

    deleteGreetH _ = pure NoContent

-- Turn the server into a WAI app. 'serve' is provided by servant,
-- more precisely by the Servant.Server module.
test :: Application
test = serve testApi server

-- Run the server.
--
-- 'run' comes from Network.Wai.Handler.Warp
runTestServer :: Port -> IO ()
runTestServer port = run port test

-- Put this all to work!
main :: IO ()
main = runTestServer 8001
