{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE TypeOperators #-}
module T1 where

import Data.Aeson
import Data.Time.Calendar
import GHC.Generics
import Network.Wai
import Servant

data User = User
  { name :: String
  , age :: Int
  , email :: String
  , registration_date :: Day
  } deriving (Eq, Show, Generic)

-- orphan ToJSON instance for Day. necessary to derive one for User
instance ToJSON Day where
  -- display a day in YYYY-mm-dd format
  toJSON d = toJSON (showGregorian d)

instance ToJSON User

type UserAPI = "users" :> Get '[JSON] [User]

users :: [User]
users = 
  [ User "Isaac Newton"    372 "isaac@newton.co.uk" (fromGregorian 1683  3 1)
  , User "Albert Einstein" 136 "ae@mc2.org"         (fromGregorian 1905 12 1)
  ]

userAPI :: Proxy UserAPI
userAPI = Proxy

server :: Server UserAPI
server = return users

app :: Application
app = serve userAPI server