graphql-engine/server/src-lib/Hasura/RQL/DDL/FeatureFlag.hs

-- | 'get_feature_flag' Metadata API action. Given a feature flag
-- identifier, it returns the value of the flag and its description.
module Hasura.RQL.DDL.FeatureFlag
  ( -- * Get Feature Flag
    GetFeatureFlag (..),
    runGetFeatureFlag,
  )
where

--------------------------------------------------------------------------------

import Data.Aeson (FromJSON, (.:), (.=))
import Data.Aeson qualified as J
import Data.HashMap.Strict qualified as HashMap
import Hasura.Base.Error qualified as Error
import Hasura.EncJSON (EncJSON)
import Hasura.EncJSON qualified as EncJSON
import Hasura.Prelude
import Hasura.Server.Init.FeatureFlag qualified as FeatureFlag
import Hasura.Server.Types qualified as Types

--------------------------------------------------------------------------------

newtype GetFeatureFlag = GetFeatureFlag {gfgIdentifier :: Text}

instance FromJSON GetFeatureFlag where
  parseJSON = J.withObject "GetFeatureFlag" \o -> do
    gfgIdentifier <- o .: "identifier"
    pure $ GetFeatureFlag {..}

runGetFeatureFlag ::
  ( MonadError Error.QErr m,
    MonadIO m
  ) =>
  Types.CheckFeatureFlag ->
  GetFeatureFlag ->
  m EncJSON
runGetFeatureFlag (Types.CheckFeatureFlag getFeatureFlag) GetFeatureFlag {..} = do
  let flagM = HashMap.lookup gfgIdentifier $ FeatureFlag.getFeatureFlags $ FeatureFlag.featureFlags
  case flagM of
    Nothing -> Error.throw400 Error.NotFound $ "Feature Flag '" <> gfgIdentifier <> "' not found"
    Just flag -> do
      flagValue <- liftIO $ getFeatureFlag flag
      pure $
        EncJSON.encJFromJValue $
          J.object
            [ "identifier" .= gfgIdentifier,
              "value" .= flagValue,
              "description" .= FeatureFlag.ffDescription flag
            ]