{-# LANGUAGE DataKinds                  #-}
{-# LANGUAGE DeriveDataTypeable         #-}
{-# LANGUAGE DeriveGeneric              #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE OverloadedStrings          #-}
{-# LANGUAGE TypeOperators              #-}
module Todo where

import Control.Lens
import Data.Aeson
import Data.Proxy
import Data.Text (Text)
import Data.Time (UTCTime(..), fromGregorian)
import Data.Typeable (Typeable)
import Data.Swagger
import GHC.Generics
import Servant
import Servant.Swagger

todoAPI :: Proxy TodoAPI
todoAPI = Proxy

-- | The API of a Todo service.
type TodoAPI
    = "todo" :> Get '[JSON] [Todo]
 :<|> "todo" :> ReqBody '[JSON] Todo :> Post '[JSON] TodoId
 :<|> "todo" :> Capture "id" TodoId :> Get '[JSON] Todo
 :<|> "todo" :> Capture "id" TodoId :> ReqBody '[JSON] Todo :> Put '[JSON] TodoId

-- | API for serving @swagger.json@.
type SwaggerAPI = "swagger.json" :> Get '[JSON] Swagger

-- | Combined API of a Todo service with Swagger documentation.
type API = SwaggerAPI :<|> TodoAPI

-- | A single Todo entry.
data Todo = Todo
  { created :: UTCTime  -- ^ Creation datetime.
  , summary :: Text     -- ^ Task summary.
  } deriving (Show, Generic, Typeable)

-- | A unique Todo entry ID.
newtype TodoId = TodoId Int
  deriving (Show, Generic, Typeable, ToJSON, FromText)

instance ToJSON Todo
instance FromJSON Todo

instance ToSchema Todo where
  declareNamedSchema proxy = genericDeclareNamedSchema defaultSchemaOptions proxy
    & mapped.schema.description ?~ "This is some real Todo right here"
    & mapped.schema.example ?~ toJSON (Todo (UTCTime (fromGregorian 2015 12 31) 0) "get milk")

instance ToParamSchema TodoId
instance ToSchema TodoId

-- | Swagger spec for Todo API.
todoSwagger :: Swagger
todoSwagger = toSwagger todoAPI
  & info.title   .~ "Todo API"
  & info.version .~ "1.0"
  & info.description ?~ "This is an API that tests swagger integration"
  & info.license ?~ ("MIT" & url ?~ URL "http://mit.com")

-- | Combined server of a Todo service with Swagger documentation.
server :: Server API
server = return todoSwagger :<|> error "not implemented"