{-# LANGUAGE FlexibleContexts  #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TemplateHaskell   #-}

{- Facebook example -}

module Main where

import           Keys                       (facebookKey)
import           Network.OAuth.OAuth2

import           Data.Aeson                 (FromJSON)
import           Data.Aeson.TH              (defaultOptions, deriveJSON)
import qualified Data.ByteString.Char8      as BS
import qualified Data.ByteString.Lazy.Char8 as BL
import           Data.Text                  (Text)
import           Network.HTTP.Conduit
import           Prelude                    hiding (id)

--------------------------------------------------

data User = User { id    :: Text
                 , name  :: Text
                 , email :: Text
                 } deriving (Show)

$(deriveJSON defaultOptions ''User)

--------------------------------------------------

main :: IO ()
main = do
    print $ authorizationUrl facebookKey `appendQueryParam` facebookScope
    putStrLn "visit the url and paste code here: "
    code <- fmap BS.pack getLine
    mgr <- newManager tlsManagerSettings
    let (url, body) = accessTokenUrl facebookKey code
    resp <- doJSONPostRequest mgr facebookKey url (body ++ [("state", "test")])
    case (resp :: OAuth2Result AccessToken) of
      Right token -> do
                     print token
                     --userinfo mgr token >>= print
                     userinfo' mgr token >>= print
      Left l -> print l

--------------------------------------------------
-- FaceBook API

-- | Gain read-only access to the user's id, name and email address.
facebookScope :: QueryParams
facebookScope = [("scope", "user_about_me,email")]

-- | Fetch user id and email.
userinfo :: Manager -> AccessToken -> IO (OAuth2Result BL.ByteString)
userinfo mgr token = authGetBS mgr token "https://graph.facebook.com/me?fields=id,name,email"

userinfo' :: FromJSON User => Manager -> AccessToken -> IO (OAuth2Result User)
userinfo' mgr token = authGetJSON mgr token "https://graph.facebook.com/me?fields=id,name,email"