{-# language TypeApplications #-}
{-# language DataKinds #-}
{-# language LambdaCase #-}
{-# options_ghc -Wall -Werror #-}
module Main (main) where

import GHC.Exts (IsList(..))
import Data.Foldable (traverse_)
import System.Exit (ExitCode(ExitSuccess, ExitFailure), exitWith)
import Bloom (Bloom)
import qualified Bloom
import qualified Data.Binary as Binary
import qualified Data.ByteString.Lazy as ByteString
import System.Directory
import System.FilePath
import System.Environment
import Control.Monad (guard)

main :: IO ()
main = do
  b <- cachedLoad
  input <- lines <$> getContents
  let ws' = filter (not . (`Bloom.elem` b)) input
  traverse_ putStrLn ws'
  exitWith (if null ws' then ExitSuccess else ExitFailure 1)

cachedLoad :: IO (Bloom Size String)
cachedLoad = do
  cache <- getCachePath
  load cache >>= \case
    Nothing -> do
      b <- build
      ByteString.writeFile cache $ Binary.encode b
      pure b
    Just a -> pure a

getCachePath :: IO FilePath
getCachePath = (</> "bloom-spell/words.bin") <$> getEnv "XDG_DATA_HOME"

load :: FilePath -> IO (Maybe (Bloom Size String))
load p = do
  cacheExists <- doesFileExist p
  guard cacheExists
  s <- ByteString.readFile p
  case Binary.decodeOrFail @(Bloom Size _) s of
    Left{} -> pure Nothing
    Right (_, _, a) -> pure $ pure a

build :: IO (Bloom Size String)
build = fromList @(Bloom Size _) . lines <$> readFile dict

type Size = 0xffff0

dict :: FilePath
dict = "/usr/share/dict/words"