module Hasura.GraphQL.Transport.Backend where

import           Hasura.Prelude

import qualified Data.ByteString                        as B
import qualified Language.GraphQL.Draft.Syntax          as G

import qualified Hasura.Logging                         as L

import           Hasura.Base.Error
import           Hasura.EncJSON
import           Hasura.GraphQL.Execute.Backend
import           Hasura.GraphQL.Execute.LiveQuery.Plan
import           Hasura.GraphQL.Logging                 (MonadQueryLog)
import           Hasura.GraphQL.Transport.HTTP.Protocol
import           Hasura.RQL.Types.Backend
import           Hasura.SQL.Backend
import           Hasura.Server.Types                    (RequestId)
import           Hasura.Session
import           Hasura.Tracing


-- | This typeclass enacapsulates how a given backend sends queries and mutations over the
-- network. Each backend is currently responsible for both logging and tracing, for now.
class BackendExecute b => BackendTransport (b :: BackendType) where
  runDBQuery
    :: forall m
     . ( MonadIO m
       , MonadError QErr m
       , MonadQueryLog m
       , MonadTrace m
       )
    => RequestId
    -> GQLReqUnparsed
    -> G.Name
    -> UserInfo
    -> L.Logger L.Hasura
    -> SourceConfig b
    -> ExecutionMonad b EncJSON
    -> Maybe (PreparedQuery b)
    -> m (DiffTime, EncJSON)
  runDBMutation
    :: forall m
     . ( MonadIO m
       , MonadError QErr m
       , MonadQueryLog m
       , MonadTrace m
       )
    => RequestId
    -> GQLReqUnparsed
    -> G.Name
    -> UserInfo
    -> L.Logger L.Hasura
    -> SourceConfig b
    -> ExecutionMonad b EncJSON
    -> Maybe (PreparedQuery b)
    -> m (DiffTime, EncJSON)
  runDBSubscription
    :: forall m
     . ( MonadIO m
       )
    => SourceConfig b
    -> MultiplexedQuery b
    -> [(CohortId, CohortVariables)]
    -- ^ WARNING: Postgres-specific, ignored by other backends
    -> m (DiffTime, Either QErr [(CohortId, B.ByteString)])
  runDBQueryExplain
    :: forall m
     . ( MonadIO m
       , MonadError QErr m
       )
    => DBStepInfo b
    -> m EncJSON