module Yesod.Session.Storage.Yesod
  ( -- * More general
    makeSessionBackend'
  , SessionConfiguration' (..)

    -- * Extra general
  , makeSessionBackend''

    -- * Reëxport
  , SessionBackend
  ) where

import Internal.Prelude

import Data.Text.Encoding (encodeUtf8)
import Session.Key
import Yesod.Core.Types (SessionBackend (..))
import Yesod.Session.Cookie.Logic
import Yesod.Session.Cookie.Reading
import Yesod.Session.Manager
import Yesod.Session.Manager.Load
import Yesod.Session.Manager.Save
import Yesod.Session.Options
import Yesod.Session.Storage.Operation

data SessionConfiguration' session = forall tx.
  Monad tx =>
  SessionConfiguration'
  { storage :: forall a. StorageOperation a -> tx a
  , options :: Options tx IO
  , runDB :: forall a. tx a -> IO a
  }

makeSessionBackend' :: SessionConfiguration' session -> IO SessionBackend
makeSessionBackend' SessionConfiguration' {options = options :: Options tx m, ..} = do
  keyManager :: SessionKeyManager tx <-
    makeSessionKeyManager <$> options.randomization
  let sessionManager = SessionManager {keyManager, storage, options, runDB}
  pure $ makeSessionBackend'' sessionManager

makeSessionBackend'' :: Monad tx => SessionManager tx IO -> SessionBackend
makeSessionBackend'' sessionManager@SessionManager {options} =
  SessionBackend
    { sbLoadSession = \req -> do
        let
          cookie = findSessionKey (encodeUtf8 options.cookieName) req
          sessionKeyMaybe = cookie >>= checkedSessionKeyFromCookieValue sessionManager

        load <- loadSessionMaybe sessionManager sessionKeyMaybe

        pure
          ( loadedData load
          , \newData -> do
              save <- saveSession sessionManager load newData
              pure $ setCookie options CookieContext {cookie, load = load.got, save}
          )
    }