{-# LANGUAGE NoImplicitPrelude #-}

module System.Etc.Internal.Resolver.Default (resolveDefault) where

import           RIO
import qualified RIO.HashMap as HashMap
import qualified RIO.Set     as Set

import qualified Data.Aeson as JSON

import qualified System.Etc.Internal.Spec.Types as Spec
import           System.Etc.Internal.Types

toDefaultConfigValue :: Bool -> JSON.Value -> ConfigValue
toDefaultConfigValue sensitive =
  ConfigValue . Set.singleton . Default . boolToValue sensitive

buildDefaultResolver :: Spec.ConfigSpec cmd -> Maybe ConfigValue
buildDefaultResolver spec =
  let resolverReducer
        :: Text -> Spec.ConfigValue cmd -> Maybe ConfigValue -> Maybe ConfigValue
      resolverReducer specKey specValue mConfig = case specValue of
        Spec.ConfigValue def sensitive _ ->
          let mConfigSource = toDefaultConfigValue sensitive <$> def

              updateConfig  = writeInSubConfig specKey <$> mConfigSource <*> mConfig
          in  updateConfig <|> mConfig

        Spec.SubConfig specConfigMap ->
          let mSubConfig =
                specConfigMap
                  & HashMap.foldrWithKey resolverReducer (Just emptySubConfig)
                  & filterMaybe isEmptySubConfig

              updateConfig = writeInSubConfig specKey <$> mSubConfig <*> mConfig
          in  updateConfig <|> mConfig
  in  Spec.specConfigValues spec
      & HashMap.foldrWithKey resolverReducer (Just emptySubConfig)
      & filterMaybe isEmptySubConfig

{-|

Gathers all default values from the @etc/spec@ entries inside a @ConfigSpec@

-}
resolveDefault
  :: Spec.ConfigSpec cmd -- ^ ConfigSpec
  -> Config              -- ^ returns Configuration Map with default values included
resolveDefault spec = maybe (Config emptySubConfig) Config (buildDefaultResolver spec)