-- | Validate native queries against postgres-like flavors.
module Hasura.Backends.Postgres.Instances.NativeQueries
  ( validateNativeQuery,
  )
where

import Data.Aeson (toJSON)
import Database.PG.Query qualified as PG
import Hasura.Backends.Postgres.Connection qualified as PG
import Hasura.Backends.Postgres.Connection.Connect (withPostgresDB)
import Hasura.Base.Error
import Hasura.NativeQuery.Metadata
import Hasura.Prelude
import Hasura.SQL.Backend

-- | Prepare a native query against a postgres-like database to validate it.
validateNativeQuery :: (MonadIO m, MonadError NativeQueryError m) => PG.PostgresConnConfiguration -> NativeQueryInfoImpl ('Postgres pgKind) -> m ()
validateNativeQuery connConf nativeQuery = do
  let name = getNativeQueryNameImpl $ nqiiRootFieldName nativeQuery
  let code :: Text
      code = fold $ flip evalState (1 :: Int) do
        for (getInterpolatedQuery $ nqiiCode nativeQuery) \case
          IIText t -> pure t
          IIVariable _v -> do
            i <- get
            modify (+ 1)
            pure $ "$" <> tshow i
  result <-
    liftIO $
      withPostgresDB connConf $
        PG.rawQE
          ( \e ->
              (err400 ValidationFailed "Failed to validate query")
                { qeInternal = Just $ ExtraInternal $ toJSON e
                }
          )
          (PG.fromText $ "PREPARE _naqi_vali_" <> name <> " AS " <> code)
          []
          False
  case result of
    -- running the query failed
    Left err ->
      throwError $ NativeQueryValidationError err
    -- running the query succeeded
    Right () ->
      pure ()