slackbuilder/lib/SlackBuilder/Trans.hs

{- This Source Code Form is subject to the terms of the Mozilla Public License,
   v. 2.0. If a copy of the MPL was not distributed with this file, You can
   obtain one at https://mozilla.org/MPL/2.0/. -}

-- | Transformers and exceptions.
module SlackBuilder.Trans
    ( SlackBuilderException(..)
    , SlackBuilderT(..)
    , relativeToRepository
    ) where

import Control.Monad.Trans.Reader (ReaderT(..), asks)
import Data.Text (Text)
import SlackBuilder.Config
import Control.Monad.IO.Class (MonadIO(..))
import Control.Monad.Catch (MonadCatch(..), MonadThrow(..))
import Control.Exception (Exception(..))
import System.FilePath ((</>))
import Text.URI (URI)

data SlackBuilderException
    = UpdaterNotFound Text
    | HttpsUrlExpected URI
    deriving Show

instance Exception SlackBuilderException

newtype SlackBuilderT a = SlackBuilderT
    { runSlackBuilderT :: ReaderT Settings IO a
    }

relativeToRepository :: FilePath -> SlackBuilderT FilePath
relativeToRepository filePath =
    (</> filePath) <$> SlackBuilderT (asks repository)

instance Functor SlackBuilderT
  where
    fmap f (SlackBuilderT slackBuilderT) = SlackBuilderT $ f <$> slackBuilderT

instance Applicative SlackBuilderT
  where
    pure = SlackBuilderT . pure
    (SlackBuilderT f) <*> (SlackBuilderT x) = SlackBuilderT $ f <*> x

instance Monad SlackBuilderT
  where
    return = pure
    (SlackBuilderT x) >>= f = SlackBuilderT $ x >>= runSlackBuilderT . f

instance MonadIO SlackBuilderT
  where
    liftIO = SlackBuilderT . liftIO

instance MonadThrow SlackBuilderT
  where
    throwM = SlackBuilderT . throwM

instance MonadCatch SlackBuilderT
  where
    catch (SlackBuilderT action) handler =
        SlackBuilderT $ catch action $ runSlackBuilderT . handler