{-# LANGUAGE NamedFieldPuns #-}
module Lang.En.Morpheme (
      Morpheme(..)
    , Output(..)
    , morphemes
    , parse
  ) where

import Data.String (fromString)
import Lang.En.Grapheme (Grapheme(..))
import qualified Lang.En.Grapheme as Grapheme (Output(..))
import Stream (Stream)
import Transducer (Transducer(..), fromList, run)

data Regular =
    LY
  | ED
  | UN
  | CAT
  | DOG
  | EaT
  | SLEeP
  | A
  | ThE
  | GOoD
  | KINd
  | ANd
  | Space
  deriving (Bounded, Enum, Eq, Ord, Show)

data Morpheme = Morpheme Regular | Punctuation String deriving (Eq, Ord, Show)

auto :: Morpheme -> ([Grapheme], Either [Grapheme] Morpheme)
auto morpheme = (fromString $ show morpheme, Right morpheme)

morphemes :: Transducer Grapheme.Output Grapheme Morpheme
morphemes = (fromList $ auto <$> [minBound .. maxBound]) {
      projector = Grapheme.grapheme
    , rules = []
  }

data Output = Output {
      rawText :: String
    , morpheme :: Morpheme
  } deriving (Eq, Show)

parse :: Stream Grapheme.Output -> Stream Output
parse = fmap fusionGraphemes . run morphemes
  where
    fusionGraphemes (graphemes, morpheme) = Output {
          rawText = concat $ Grapheme.rawText <$> graphemes
        , morpheme
      }