{-# LANGUAGE DeriveAnyClass #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE OverloadedStrings #-}

{- |
Module      :  Data.GraphQL.Error
Maintainer  :  Brandon Chinn <brandon@leapyear.io>
Stability   :  experimental
Portability :  portable

Definitions for GraphQL errors and exceptions.
-}
module Data.GraphQL.Error (
  GraphQLError (..),
  GraphQLErrorLoc (..),
  GraphQLException (..),
) where

import Control.Exception (Exception)
import Data.Aeson (FromJSON (..), ToJSON, Value, withObject, (.:))
import Data.Text (Text)
import GHC.Generics (Generic)

-- | An error in a GraphQL query.
data GraphQLError = GraphQLError
  { message :: Text
  , locations :: Maybe [GraphQLErrorLoc]
  , path :: Maybe [Value]
  }
  deriving (Show, Eq, Generic, ToJSON, FromJSON)

-- | A location in an error in a GraphQL query.
data GraphQLErrorLoc = GraphQLErrorLoc
  { errorLine :: Int
  , errorCol :: Int
  }
  deriving (Show, Eq, Generic, ToJSON)

instance FromJSON GraphQLErrorLoc where
  parseJSON = withObject "GraphQLErrorLoc" $ \o ->
    GraphQLErrorLoc
      <$> o .: "line"
      <*> o .: "column"

-- | An exception thrown as a result of an error in a GraphQL query.
newtype GraphQLException = GraphQLException [GraphQLError]
  deriving (Show, Exception, Eq)