Exception.hs

{-# LANGUAGE ExistentialQuantification #-}

module Dormouse.Client.Exception 
  ( SomeDormouseException(..)
  , DecodingException(..)
  , UnexpectedStatusCodeException(..)
  , MediaTypeException(..)
  , UriException(..)
  , UrlException(..)
  ) where

  
import Control.Exception.Safe (Exception(..))
import Dormouse.Uri.Exception (UriException(..))
import Dormouse.Url.Exception (UrlException(..))
import qualified Data.Text as T
import Data.Typeable (cast)

data SomeDormouseException = forall e . Exception e => SomeDormouseException e

instance Show SomeDormouseException where
    show (SomeDormouseException e) = show e

instance Exception SomeDormouseException

-- | 'UnexpectedStatusCodeException' is used to indicate that the remote server returned an unexpected status code value, for instance an unsuccessful (non-2XX) status code.
newtype UnexpectedStatusCodeException = UnexpectedStatusCodeException { uscStatusCode :: Int }

instance Show UnexpectedStatusCodeException where
  show UnexpectedStatusCodeException { uscStatusCode = statusCode } = "Server returned unexpected status code: " <> show statusCode

instance Exception UnexpectedStatusCodeException where
  toException     = toException . SomeDormouseException
  fromException x = do
    SomeDormouseException a <- fromException x
    cast a

-- | 'DecodingException' is used to when something has gone wrong decoding an http response into the expected representation, e.g. json was expected but the response json was invalid.
newtype DecodingException = DecodingException { decodingExceptionMessage :: T.Text }

instance Show DecodingException where
  show DecodingException { decodingExceptionMessage = msg } = "Decoding payload failed: " <> T.unpack msg

instance Exception DecodingException

-- | 'MediaTypeException' is used to indicate an error parsing a MediaType header such as "Content-Type" into a valid 'MediaType'
newtype MediaTypeException = MediaTypeException  { mediaTypeExceptionMessage :: T.Text }

instance Show MediaTypeException where
  show MediaTypeException { mediaTypeExceptionMessage = msg } = "Failed to parse media type: " <> show msg

instance Exception MediaTypeException where
  toException     = toException . SomeDormouseException
  fromException x = do
    SomeDormouseException a <- fromException x
    cast a