{-# LANGUAGE OverloadedStrings #-}

module LoginSession
  ( put
  , get
  , delete
  ) where

import Web.Scotty (ActionM)
import Web.Scotty.Cookie (setSimpleCookie, getCookie, deleteCookie)
import qualified Web.ClientSession as CS

import Control.Monad.IO.Class (liftIO)

import Data.Text (Text)
import qualified Data.Text.Encoding as TE

sessionName :: Text
sessionName = "SESSION"

sessionKeyFile :: FilePath
sessionKeyFile = "sessionKey"

put :: Text -> ActionM ()
put value = do
  encrypted <- liftIO $ encrypt value
  setSimpleCookie sessionName encrypted

encrypt :: Text -> IO Text
encrypt value = do
  iv <- CS.randomIV
  key <- CS.getKey sessionKeyFile
  return . TE.decodeUtf8 $ CS.encrypt key iv (TE.encodeUtf8 value)

get :: ActionM (Maybe Text)
get = do
  maybeEncrypted <- getCookie sessionName
  case maybeEncrypted of
    Just encrypted ->
      liftIO $ decrypt encrypted
    Nothing ->
      return Nothing

decrypt :: Text -> IO (Maybe Text)
decrypt encrypted = do
  key <- CS.getKey sessionKeyFile
  let decrypted = TE.decodeUtf8 <$> CS.decrypt key (TE.encodeUtf8 encrypted)
  return decrypted

delete :: ActionM ()
delete = deleteCookie sessionName