content: {-
    Copyright 2020 The CodeWorld Authors. All rights reserved.
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at
        http://www.apache.org/licenses/LICENSE-2.0
    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
  -}
  
  -- |
  -- Snap helper functions
  module CodeWorld.Auth.Util
    ( getRequiredParam,
      hoistEither,
      hoistMaybe,
      m,
      withSnapExcept,
    )
  where
  
  import CodeWorld.Auth.Http
  import CodeWorld.Auth.Types
  import Control.Monad.Trans.Except (ExceptT (..), runExceptT, throwE)
  import Data.ByteString (ByteString)
  import Data.HashMap.Strict (HashMap)
  import qualified Data.HashMap.Strict as HashMap (fromList)
  import Snap.Core (Snap, finishWith, getParam)
  
  getRequiredParam :: ByteString -> Snap ByteString
  getRequiredParam name = do
    mbValue <- getParam name
    case mbValue of
      Nothing -> finishWith badRequest400
      Just value -> return value
  
  m :: [(String, String)] -> HashMap String String
  m = HashMap.fromList
  
  hoistMaybe :: Monad m => e -> Maybe a -> ExceptT e m a
  hoistMaybe e mb = maybe (throwE e) return mb
  
  hoistEither :: Monad m => Either e a -> ExceptT e m a
  hoistEither = ExceptT . return
  
  withSnapExcept :: SnapExcept a
  withSnapExcept action = runExceptT action >>= either id return
  