graphql-engine/server/src-lib/Hasura/GraphQL/Schema/RemoteSource.hs

module Hasura.GraphQL.Schema.RemoteSource
  ( remoteSourceField,
  )
where

import Hasura.GraphQL.Parser
import Hasura.GraphQL.Schema.Backend
import Hasura.GraphQL.Schema.Common
import Hasura.GraphQL.Schema.Instances ()
import Hasura.GraphQL.Schema.Select
import Hasura.GraphQL.Schema.Table
import Hasura.Prelude
import Hasura.RQL.IR.Select qualified as IR
import Hasura.RQL.Types.Common (RelType (..))
import Hasura.RQL.Types.RemoteRelationship
import Hasura.SQL.AnyBackend
import Language.GraphQL.Draft.Syntax qualified as G

-- | TODO(jkachmar): Documentation.
remoteSourceField ::
  forall b r m n.
  MonadBuildSchema b r m n =>
  AnyBackend (RemoteSourceRelationshipInfo b) ->
  m [FieldParser n (AnnotatedField b)]
remoteSourceField remoteDB = dispatchAnyBackend @BackendSchema remoteDB buildField
  where
    buildField ::
      forall src tgt.
      BackendSchema tgt =>
      RemoteSourceRelationshipInfo src tgt ->
      m [FieldParser n (AnnotatedField src)]
    buildField (RemoteSourceRelationshipInfo {..}) = do
      tableInfo <- askTableInfo @tgt _rsriSource _rsriTable
      fieldName <- textToName $ remoteRelationshipNameToText _rsriName
      maybePerms <- tableSelectPermissions @tgt tableInfo
      case maybePerms of
        Nothing -> pure []
        Just tablePerms -> do
          parsers <- case _rsriType of
            ObjRel -> do
              selectionSetParser <- tableSelectionSet _rsriSource tableInfo tablePerms
              pure $
                pure $
                  subselection_ fieldName Nothing selectionSetParser <&> \fields ->
                    IR.SourceRelationshipObject $
                      IR.AnnObjectSelectG fields _rsriTable $
                        IR._tpFilter $
                          tablePermissionsInfo tablePerms
            ArrRel -> do
              let aggFieldName = fieldName <> $$(G.litName "_aggregate")
              selectionSetParser <- selectTable _rsriSource tableInfo fieldName Nothing tablePerms
              aggSelectionSetParser <- selectTableAggregate _rsriSource tableInfo aggFieldName Nothing tablePerms
              pure $
                catMaybes
                  [ Just $ selectionSetParser <&> IR.SourceRelationshipArray,
                    aggSelectionSetParser <&> fmap IR.SourceRelationshipArrayAggregate
                  ]
          pure $
            parsers <&> fmap \select ->
              IR.AFRemote $
                IR.RemoteSelectSource $
                  mkAnyBackend @tgt $
                    IR.RemoteSourceSelect _rsriSource _rsriSourceConfig select _rsriMapping