{-# OPTIONS_HADDOCK show-extensions #-}
{-# LANGUAGE NoImplicitPrelude #-}

-- |
-- Module      :  Phladiprelio.Coeffs
-- Copyright   :  (c) OleksandrZhabenko 2020-2023
-- License     :  MIT
-- Stability   :  Experimental
-- Maintainer  :  oleksandr.zhabenko@yahoo.com
--
-- The coefficients functionality common for both phonetic-languages-simplified-examples-array and phonetic-languages-simplified-generalized-examples-array lines of PhLADiPreLiO.

{-# LANGUAGE BangPatterns #-}

module Phladiprelio.Coeffs (
    -- * Newtype to work with
  CoeffTwo(..)
  , Coeffs2
  , isEmpty
  , isPair
  , fstCF
  , sndCF
  , readCF
) where

import GHC.Base
import GHC.List
import Data.Maybe (isNothing,fromMaybe,fromJust)
import Text.Read (readMaybe)

data CoeffTwo a = CF0 | CF2 (Maybe a) (Maybe a) deriving (Eq)

isEmpty :: CoeffTwo a -> Bool
isEmpty CF0 = True
isEmpty _ = False

isPair :: CoeffTwo a -> Bool
isPair CF0 = False
isPair _ = True

fstCF :: CoeffTwo a -> Maybe a
fstCF (CF2 x _) = x
fstCF _ = Nothing

sndCF :: CoeffTwo a -> Maybe a
sndCF (CF2 _ y) = y
sndCF _ = Nothing

readCF :: String -> Coeffs2
readCF xs
  | any (== '_') xs = let (!ys,!zs) = (\(ks,ts) -> (readMaybe ks::Maybe Double,readMaybe (drop 1 ts)::Maybe Double)) . break (== '_') $ xs in
     if (isNothing ys && isNothing zs) then CF0 else CF2 ys zs
  | otherwise = CF0

-- | A data type that is used to represent the coefficients of the rhythmicity functions as a one argument value.
type Coeffs2 = CoeffTwo Double