-- | Copyright: (c) 2025 Joshua Moerman, Open Universiteit
-- SPDX-License-Identifier: EUPL-1.2
module DecomposeTemp where

import DotParser (readDotFile)
import Mealy

import Control.Monad (unless)
import Data.List (nub, sort)
import Data.Maybe (mapMaybe)
import Data.Set qualified as Set
import Data.Text (Text)
import Options.Applicative

-- Nog een experiment

data DecomposeTempOptions = DecomposeTempOptions
  { filename :: FilePath
  , quiescence :: Text
  , numComponents :: Int
  }
  deriving Show

decomposeTempOptionsParser :: Parser DecomposeTempOptions
decomposeTempOptionsParser =
  DecomposeTempOptions
    <$> argument str (help "Filename to read (dot format)" <> metavar "FILE")
    <*> option str (long "quiescence" <> help "String denoting empty output" <> showDefault <> value "quiescence")
    <*> option auto (long "components" <> short 'c' <> help "Number of components" <> metavar "NUM" <> showDefault <> value 2)

mainDecomposeTemp :: DecomposeTempOptions -> IO ()
mainDecomposeTemp DecomposeTempOptions{..} = do
  putStrLn $ "reading " <> filename <> " and quiescence=" <> show quiescence
  MealyMachine{..} <- readDotFile filename

  let
    quiescenceTransitions s = mapMaybe (\i -> let (o, t) = behaviour s i in if o == quiescence then Just (s, t) else Nothing) inputs
    valid = all (uncurry (==)) . quiescenceTransitions

  unless (all valid states) $ do
    putStrLn "WARNING: Not all quiescence-transistions are self-loops!"

  let
    definedTransitions s = mapMaybe (\i -> let (o, t) = behaviour s i in if o /= quiescence || s /= t then Just (s, i, o, t) else Nothing) inputs
    showState s trns = putStrLn $ show s <> ": " <> show (fmap (\(_, i, _, _) -> i) trns)

    bfs [] _ = []
    bfs (x : todo) visited
      | x `Set.member` visited = bfs todo visited
      | otherwise =
          let trns = definedTransitions x
           in (x, sort trns) : bfs (todo <> nub (fmap (\(_, _, _, t) -> t) trns)) (Set.insert x visited)

  mapM_ (uncurry showState) (bfs [initialState] Set.empty)