module Main (main) where
import qualified Data.Text.IO as Text
import Text.Megaparsec (errorBundlePretty, runParser)
import qualified Data.Text as Text
import qualified Sudoku
import qualified Sudoku.Solve as Solve
import qualified Sudoku.Render as Render
import Sudoku.State (State)
import Options.Applicative (subparser, command, info, Parser, progDesc, execParser, idm, customExecParser, ParserPrefs, showHelpOnEmpty, prefs)
import System.Exit (exitFailure)

data Mode
  = Solve
  | Hints

parseMode :: Parser Mode
parseMode = subparser
  (     command "solve" (info (pure Solve) (progDesc "Solve the supplied sudoku entirely."))
  <>    command "hints" (info (pure Hints) (progDesc "Show hints for the sudoku."))
  )

main :: IO ()
main = do
  mode <- customExecParser optparsePreferences (info parseMode idm)
  input <- Text.getContents
  sudoku <- case runParser Sudoku.parse "<stdin>" input of
    Left errorBundle -> (Text.putStr . Text.pack . errorBundlePretty $ errorBundle) >> exitFailure
    Right s -> pure s

  Text.putStr $ case mode of
    Solve -> Text.pack . show $ Solve.solve State sudoku
    Hints -> let
      hints = Solve.hints State sudoku

      in Render.hints hints

optparsePreferences :: ParserPrefs
optparsePreferences = prefs showHelpOnEmpty