module Site.Lang where

import Data.Aeson (FromJSON (parseJSON), withText)
import Data.Text qualified as Text
import Relude
import Prelude ()

-- * Type 'Lang'
data Lang
  = LangDe
  | LangEn
  | LangFr
  | LangJp
  deriving (Bounded, Show, Enum, Eq)

langText :: IsString a => Lang -> a
langText = \case
  LangDe -> "Deutsch"
  LangEn -> "English"
  LangFr -> "français"
  LangJp -> "日本語"

parseLang :: Text -> Maybe Lang
parseLang = \case
  "de" -> Just LangDe
  "en" -> Just LangEn
  "fr" -> Just LangFr
  "jp" -> Just LangJp
  _ -> Nothing

instance FromJSON Lang where
  parseJSON =
    withText "Lang" $
      maybe (fail "expected a Lang") pure
        . parseLang

textOfLang :: Lang -> Text
textOfLang = Text.drop 4 . Text.toLower . show