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{- 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/. -}
{-# LANGUAGE LambdaCase #-}
module Language.GraphQL.Executor
( Error(..)
, Operation(..)
, QueryError(..)
, Response(..)
, Segment(..)
, executeRequest
) where
import qualified Language.GraphQL.AST.Document as Full
import qualified Data.Aeson as Aeson
import Data.Foldable (find)
import qualified Data.Text as Text
import qualified Language.GraphQL.Type.Internal as Type.Internal
data Segment = Segment String | Index Int
data Error = Error
{ message :: String
, locations :: [Full.Location]
, path :: [Segment]
}
data Response = Response
{ data' :: Aeson.Object
, errors :: [Error]
}
data QueryError
= OperationNameRequired
| OperationNotFound String
instance Show QueryError where
show OperationNameRequired = "Operation name is required."
show (OperationNotFound operationName) =
concat ["Operation \"", operationName, "\" not found."]
respondWithQueryError :: QueryError -> Response
respondWithQueryError queryError
= Response mempty
$ pure
$ Error{ message = show queryError, locations = [], path = [] }
-- operationName selectionSet location
data Operation = Operation
Full.OperationType
(Maybe String)
[Full.VariableDefinition]
Full.SelectionSet
Full.Location
document :: Full.Document -> [Operation]
document = foldr filterOperation []
where
filterOperation (Full.ExecutableDefinition executableDefinition) accumulator
| Full.DefinitionOperation operationDefinition' <- executableDefinition =
operationDefinition operationDefinition' : accumulator
filterOperation _ accumulator = accumulator -- Fragment.
operationDefinition :: Full.OperationDefinition -> Operation
operationDefinition = \case
Full.OperationDefinition operationType operationName variables _ selectionSet operationLocation ->
let maybeOperationName = Text.unpack <$> operationName
in Operation operationType maybeOperationName variables selectionSet operationLocation
Full.SelectionSet selectionSet operationLocation ->
Operation Full.Query Nothing [] selectionSet operationLocation
executeRequest :: Type.Internal.Schema IO
-> Full.Document
-> Maybe String
-> Aeson.Object
-> Aeson.Object
-> IO Response
executeRequest _schema sourceDocument operationName _variableValues _initialValue =
let transformedDocument = document sourceDocument
operation = getOperation transformedDocument operationName
in case operation of
Left queryError -> pure $ respondWithQueryError queryError
Right _ -> pure $ Response mempty mempty
getOperation :: [Operation] -> Maybe String -> Either QueryError Operation
getOperation [operation] Nothing = Right operation
getOperation operations (Just givenOperationName)
= maybe (Left $ OperationNotFound givenOperationName) Right
$ find findOperationByName operations
where
findOperationByName (Operation _ (Just operationName) _ _ _) =
givenOperationName == operationName
findOperationByName _ = False
getOperation _ _ = Left OperationNameRequired
|
