{-# LANGUAGE FlexibleContexts #-}

-- | These helper functions are usually used with 'Data.FileEmbed.embedFile'.
module Octane.Utility.Embed
  ( decodeBimap
  ) where

import Data.Function ((&))

import qualified Data.Aeson as Aeson
import qualified Data.Bimap as Bimap
import qualified Data.ByteString as StrictBytes
import qualified Data.Map.Strict as Map
import qualified Data.Maybe as Maybe

-- | Decodes some bytes into a bidirection map. The bytes are assumed to be a
-- JSON object mapping values to keys. That means the resulting bimap is
-- 'Bimap.twist'ed from what you might expect.
decodeBimap
  :: (Aeson.FromJSON (Map.Map b a), Ord a, Ord b)
  => StrictBytes.ByteString -> Bimap.Bimap a b
decodeBimap bytes =
  bytes & Aeson.decodeStrict & Maybe.fromMaybe Map.empty & Map.toList &
  Bimap.fromList &
  Bimap.twist