module Main where

import Control.Monad.IO.Class (liftIO)
import Data.Maybe (fromJust)
import Data.Monoid ((<>))
import Data.Text.Encoding (decodeUtf8)
import Network.Pusher (authenticatePresence)
import Snap.Core
  ( Method(GET)
  , Snap
  , getParams
  , method
  , writeBS
  )
import Snap.Http.Server (quickHttpServe)
import qualified Data.Aeson as A
import qualified Data.ByteString.Lazy as BL
import qualified Data.HashMap.Strict as HM
import qualified Data.Map as M
import qualified Data.Yaml as Y

main :: IO ()
main = quickHttpServe $ method GET authHandler

authHandler :: Snap ()
authHandler = do
    cred <- liftIO $ Y.decodeFile "example/credentials.yaml"
    params <- getParams
    let
      userData = A.Object $ HM.fromList -- Would normally come from session data
        [ ("user_id", A.Number 10)
        , ("user_info", A.Object $ HM.singleton "name" (A.String "Mr. Pusher"))]
      signature = authenticatePresence
        (fromJust cred)
        (head $ params M.! "socket_id")
        (head $ params M.! "channel_name")
        userData
      respBody = A.Object $ HM.fromList
        [ ("auth", A.String $ decodeUtf8 signature)
        , ("channel_data", A.String $ decodeUtf8 $ BL.toStrict $ A.encode userData)
        ]
    writeBS $ head (params M.! "callback") <> "(" <> BL.toStrict (A.encode respBody) <> ");"