{-# OPTIONS_GHC -threaded -rtsopts #-}
{-# OPTIONS_HADDOCK show-extensions #-}
{-# LANGUAGE BangPatterns #-}

-- |
-- Module      :  Phonetic.Languages.Parsing
-- Copyright   :  (c) OleksandrZhabenko 2021
-- License     :  MIT
-- Stability   :  Experimental
-- Maintainer  :  olexandr543@yahoo.com
--
-- The additional parsing library functions for the lineVariantsG3 executable.
-- @ since 0.3.0.0
-- 

module Phonetic.Languages.Parsing (
  -- * Predicates
  isClosingCurlyBracket
  , isSlash
  , isOpeningCurlyBracket
  , variations
  -- * Transformations
  , breakGroupOfStrings
  , breakInSlashes
  , combineVariants
  , combineHeadsWithNexts
  , transformToVariations
) where

isClosingCurlyBracket :: String -> Bool
isClosingCurlyBracket = (== "}")

isSlash :: String -> Bool
isSlash (x:xs)
 | x /= '/' = False
 | null xs = True
 | otherwise = False
isSlash _ = False

isOpeningCurlyBracket :: String -> Bool
isOpeningCurlyBracket = (== "{")

breakGroupOfStrings :: [String] -> (([String],[[String]]),[String])
breakGroupOfStrings !xss = ((tss,breakInSlashes uss []), drop 1 zss)
  where (!yss,!zss) = break isClosingCurlyBracket xss
        (!tss,!uss) = (\(t1,t2) -> (t1,drop 1 t2)) . break isOpeningCurlyBracket $ yss

breakInSlashes :: [String] -> [[String]] -> [[String]]
breakInSlashes !wss !usss
 | null lss = kss : usss
 | otherwise = breakInSlashes (drop 1 lss) (kss : usss)
  where (!kss,!lss) = break isSlash wss

combineVariants :: ([String],[[String]]) -> [[String]]
combineVariants (!xss, (!yss:ysss)) = (xss `mappend` yss) : combineVariants (xss, ysss)
combineVariants _ = []

combineHeadsWithNexts :: [[String]] -> [String] -> [[String]]
combineHeadsWithNexts !xsss !yss
 | null yss = xsss
 | otherwise = combineHeadsWithNexts [xss `mappend` zss | xss <- xsss, zss <- zsss] uss
     where (!t,!uss) = breakGroupOfStrings yss
           !zsss = combineVariants t

transformToVariations :: [String] -> [[String]]
transformToVariations !yss
 | null yss = []
 | otherwise = combineHeadsWithNexts xsss tss
  where (!y,!tss) = breakGroupOfStrings yss
        !xsss = combineVariants y

variations :: [String] -> Bool
variations xss 
 | any isSlash xss = if any isOpeningCurlyBracket xss && any isClosingCurlyBracket xss then True else False
 | otherwise = False