{-# LANGUAGE TemplateHaskell #-}

module Hasura.Backends.MySQL.SQL
  ( runSQL,
    RunSQL (..),
  )
where

import Data.Aeson qualified as J
import Data.Aeson.TH
import Data.ByteString hiding (null, reverse)
import Data.Pool (withResource)
import Data.String (fromString)
import Data.Text qualified as T
import Data.Text.Encoding (decodeUtf8With)
import Data.Text.Encoding.Error (lenientDecode)
import Database.MySQL.Base (fetchFields, query, storeResult)
import Database.MySQL.Base.Types (Field (fieldName))
import Hasura.Backends.MySQL.Connection (fetchAllRows)
import Hasura.Backends.MySQL.Types (SourceConfig (..))
import Hasura.Base.Error
import Hasura.EncJSON
import Hasura.Prelude
import Hasura.RQL.DDL.Schema (RunSQLRes (..))
import Hasura.RQL.Types

data RunSQL = RunSQL
  { _Sql :: !Text,
    _Source :: !SourceName
  }
  deriving (Show, Eq)

$(deriveJSON hasuraJSON ''RunSQL)

runSQL :: (MonadIO m, CacheRWM m, MonadError QErr m, MetadataM m) => RunSQL -> m EncJSON
runSQL (RunSQL sql source) = do
  pool <- scConnectionPool <$> askSourceConfig @'MySQL source
  result :: [[Maybe ByteString]] <- liftIO $
    withResource pool $ \conn -> do
      query conn (fromString . T.unpack $ sql)
      r <- storeResult conn
      fieldNames <- fmap (Just . fieldName) <$> fetchFields r -- fieldNames as Maybes for convenience
      rows <- fetchAllRows r
      pure (fieldNames : rows)
  pure . encJFromJValue $
    if null result
      then RunSQLRes "CommandOK" J.Null
      else RunSQLRes "TuplesOk" . J.toJSON . (fmap . fmap . fmap) (decodeUtf8With lenientDecode) $ result