graphql-engine/server/src-lib/Hasura/RQL/DDL/Webhook/Transform/Url.hs
Jesse Hallett 4d6604ba08 server: event trigger codecs
Codecs for event triggers, including webhook transforms. These are not hooked into the higher-up table metadata codec yet because some backend implementations implement event triggers with `error` which causes an error when codecs are evaluated. I plan to follow up with another PR to resolve that.

Ticket: https://hasurahq.atlassian.net/browse/GDC-585

PR-URL: https://github.com/hasura/graphql-engine-mono/pull/7237
GitOrigin-RevId: 8ce40fe6fedcf8b109d6ca50a505333df855a8ce
2022-12-15 20:38:21 +00:00

107 lines
3.7 KiB
Haskell

module Hasura.RQL.DDL.Webhook.Transform.Url
( -- * Url Transformations
Url (..),
TransformFn (..),
TransformCtx (..),
UrlTransformFn (..),
)
where
-------------------------------------------------------------------------------
import Autodocodec (HasCodec (codec), dimapCodec)
import Data.Aeson (FromJSON, ToJSON)
import Data.Aeson qualified as J
import Data.Text qualified as T
import Data.Validation
import Hasura.Prelude
import Hasura.RQL.DDL.Webhook.Transform.Class
( TemplatingEngine,
Transform (..),
TransformErrorBundle (..),
UnescapedTemplate (..),
throwErrorBundle,
wrapUnescapedTemplate,
)
import Hasura.RQL.DDL.Webhook.Transform.Request
( RequestTransformCtx,
runRequestTemplateTransform,
validateRequestUnescapedTemplateTransform',
)
import Network.URI (parseURI)
-------------------------------------------------------------------------------
-- | The actual URL string we are transforming.
--
-- This newtype is necessary because otherwise we end up with an
-- orphan instance.
newtype Url = Url {unUrl :: Text}
deriving stock (Eq, Show)
instance Transform Url where
-- NOTE: GHC does not let us attach Haddock documentation to data family
-- instances, so 'UrlTransformFn' is defined separately from this
-- wrapper.
newtype TransformFn Url = UrlTransformFn_ UrlTransformFn
deriving stock (Eq, Generic, Show)
deriving newtype (NFData, FromJSON, ToJSON)
newtype TransformCtx Url = TransformCtx RequestTransformCtx
-- NOTE: GHC does not let us attach Haddock documentation to typeclass
-- method implementations, so 'applyUrlTransformFn' is defined separately.
transform (UrlTransformFn_ fn) (TransformCtx reqCtx) = applyUrlTransformFn fn reqCtx
-- NOTE: GHC does not let us attach Haddock documentation to typeclass
-- method implementations, so 'validateUrlTransformFn' is defined separately.
validate engine (UrlTransformFn_ fn) = validateUrlTransformFn engine fn
-- | The defunctionalized transformation function on 'Url'
newtype UrlTransformFn
= Modify UnescapedTemplate
deriving stock (Eq, Generic, Show)
deriving newtype (NFData, FromJSON, ToJSON)
instance HasCodec UrlTransformFn where
codec = dimapCodec Modify coerce codec
-- | Provide an implementation for the transformations defined by
-- 'UrlTransformFn'.
--
-- If one views 'UrlTransformFn' as an interface describing URL
-- transformations, this can be seen as an implementation of these
-- transformations as normal Haskell functions.
applyUrlTransformFn ::
MonadError TransformErrorBundle m =>
UrlTransformFn ->
RequestTransformCtx ->
Url ->
m Url
applyUrlTransformFn fn context _oldUrl = case fn of
Modify unescapedTemplate -> do
let template = wrapUnescapedTemplate unescapedTemplate
resultJson <- liftEither $ runRequestTemplateTransform template context
templatedUrlTxt <- case resultJson of
J.String templatedUrlTxt -> pure templatedUrlTxt
val -> do
let errTxt = "URL Transforms must produce a JSON String: " <> tshow val
throwErrorBundle errTxt Nothing
case parseURI (T.unpack templatedUrlTxt) of
Nothing -> throwErrorBundle ("Invalid URL: " <> templatedUrlTxt) Nothing
Just _validatedUrl -> pure $ Url templatedUrlTxt
-- | Validate that the provided 'UrlTransformFn' is correct in the context of a
-- particular 'TemplatingEngine'.
--
-- This is a product of the fact that the correctness of a given transformation
-- may be dependent on zero, one, or more of the templated transformations
-- encoded within the given 'UrlTransformFn'.
validateUrlTransformFn ::
TemplatingEngine ->
UrlTransformFn ->
Validation TransformErrorBundle ()
validateUrlTransformFn engine fn = case fn of
Modify template ->
validateRequestUnescapedTemplateTransform' engine template