{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE FlexibleInstances #-}


-- | Types and functions related to the morphosyntax data layer.


module NLP.Concraft.DAG.Morphosyntax
(
-- * Segment
  Seg (..)
, mapSeg
, interpsSet
, interps

-- * Word class
, Word (..)

-- * Sentence
, Sent
, mapSent
, SentO (..)
, mapSentO

-- * Weighted collection
, module NLP.Concraft.Morphosyntax.WMap
) where


import           Prelude hiding (Word)
import           Control.Applicative ((<$>), (<*>))
-- import           Control.Arrow (first)
import           Data.Aeson
-- import           Data.Binary (Binary)
import qualified Data.Set as S
import qualified Data.Map as M
import qualified Data.Text as T
import qualified Data.Text.Lazy as L

-- import qualified Data.DAG as DAG
import           Data.DAG (DAG)
-- import qualified Data.CRF.Chain1.Constrained.DAG.Dataset.Internal as DAG
-- import           Data.CRF.Chain1.Constrained.DAG.Dataset.Internal (DAG)

import           NLP.Concraft.Morphosyntax.WMap


--------------------------
-- Segment
--------------------------


-- | A segment parametrized over a word type and a tag type.
data Seg w t = Seg {
    -- | A word represented by the segment. Typically it will be an instance of
    -- the `Word` class.
      word  :: w
    -- | A set of interpretations. To each interpretation a weight of
    -- appropriateness within the context is assigned.
    , tags  :: WMap t }
    deriving (Show)


instance ToJSON w => ToJSON (Seg w T.Text) where
    toJSON Seg{..} = object
        [ "word" .= word
        , "tags" .= unWMap tags ]

instance FromJSON w => FromJSON (Seg w T.Text) where
    parseJSON (Object v) = Seg
        <$> v .: "word"
        <*> (mkWMap <$> v .: "tags")
    parseJSON _ = error "parseJSON (segment): absurd"


-- | Map function over segment tags.
mapSeg :: Ord b => (a -> b) -> Seg w a -> Seg w b
mapSeg f w = w { tags = mapWMap f (tags w) }


-- | Interpretations of the segment.
interpsSet :: Seg w t -> S.Set t
interpsSet = M.keysSet . unWMap . tags


-- | Interpretations of the segment.
interps :: Seg w t -> [t]
interps = S.toList . interpsSet


--------------------------
-- Word class
--------------------------


class Word a where
    -- | Orthographic form.
    orth    :: a -> T.Text
    -- | Out-of-vocabulary (OOV) word.
    oov     :: a -> Bool


instance Word w => Word (Seg w t) where
    orth = orth . word
    {-# INLINE orth #-}
    oov = oov . word
    {-# INLINE oov #-}


----------------------
-- Sentence
----------------------


-- | A sentence.
-- type Sent w t = [Seg w t]
type Sent w t = DAG () (Seg w t)


-- | Map function over sentence tags.
mapSent :: Ord b => (a -> b) -> Sent w a -> Sent w b
mapSent = fmap . mapSeg


-- | A sentence with original, textual representation.
data SentO w t = SentO
    { segs  :: Sent w t
    , orig  :: L.Text }
    -- deriving (Show)


-- | Map function over sentence tags.
mapSentO :: Ord b => (a -> b) -> SentO w a -> SentO w b
mapSentO f x =
    let segs' = mapSent f (segs x)
    in  x { segs = segs' }