Exceptions.hs

{-# LANGUAGE DeriveDataTypeable #-}

{- |
Module      :  Neovim.Exceptions
Description :  General Exceptions
Copyright   :  (c) Sebastian Witte
License     :  Apache-2.0

Maintainer  :  woozletoff@gmail.com
Stability   :  experimental
Portability :  GHC
-}
module Neovim.Exceptions (
    NeovimException (..),
    exceptionToDoc,
    catchNeovimException,
) where

import Control.Exception (Exception)
import Data.MessagePack (Object (..))
import Data.String (IsString (..))
import Data.Typeable (Typeable)
import Prettyprinter (Doc, viaShow, (<+>))
import Prettyprinter.Render.Terminal (AnsiStyle)
import UnliftIO (MonadUnliftIO, catch)

-- | Exceptions specific to /nvim-hs/.
data NeovimException
    = -- | Simple error message that is passed to neovim. It should currently only
      -- contain one line of text.
      ErrorMessage (Doc AnsiStyle)
    | -- | Error that can be returned by a remote API call. The 'Doc' argument is
      -- the name of the remote function that threw this exception.
      ErrorResult (Doc AnsiStyle) Object
    deriving (Typeable, Show)

instance Exception NeovimException

instance IsString NeovimException where
    fromString = ErrorMessage . fromString

exceptionToDoc :: NeovimException -> Doc AnsiStyle
exceptionToDoc = \case
    ErrorMessage e ->
        "Error message:" <+> e
    ErrorResult fn o ->
        "Function" <+> fn <+> "has thrown an error:" <+> viaShow o

-- | Specialization of 'catch' for 'NeovimException's.
catchNeovimException :: MonadUnliftIO io => io a -> (NeovimException -> io a) -> io a
catchNeovimException action exceptionHandler = action `catch` exceptionHandler