module Yesod.Session.Manager.Load
  ( loadSessionMaybe
  , loadSession
  , loadNothing
  , Load (..)
  , didSessionLoad
  , loadedData
  ) where

import Internal.Prelude

import Control.Monad.Trans.Maybe (MaybeT (MaybeT), runMaybeT)
import Data.Map.Strict qualified as Map
import Session.Key
import Session.Timing.Math
import Session.Timing.Options
import Time
import Yesod.Core (SessionMap)
import Yesod.Session.Manager
import Yesod.Session.Options
import Yesod.Session.SessionType
import Yesod.Session.Storage.Operation

data Load a = Load
  { got :: Maybe a
  -- ^ The original session that was loaded from the database, if any
  , time :: UTCTime
  -- ^ The time at which the session was loaded
  }
  deriving stock (Eq, Show)

didSessionLoad :: Load a -> Bool
didSessionLoad = isJust . (.got)

loadedData :: Load Session -> SessionMap
loadedData load =
  maybe Map.empty (.map) load.got

loadSession :: Monad m => SessionManager tx m -> SessionKey -> m (Load Session)
loadSession SessionManager {options, storage, runDB} sessionKey = do
  now <- options.clock
  got <-
    runMaybeT $ do
      session <-
        MaybeT $ runDB $ storage $ GetSession sessionKey
      MaybeT $ pure $ guard $ not $ isExpired options.timing.timeout now session.time
      pure session
  pure Load {got, time = now}

loadNothing :: Monad m => SessionManager tx m -> m (Load a)
loadNothing SessionManager {options} = do
  now <- options.clock
  pure Load {got = Nothing, time = now}

loadSessionMaybe
  :: Monad m => SessionManager tx m -> Maybe SessionKey -> m (Load Session)
loadSessionMaybe sm = maybe (loadNothing sm) (loadSession sm)