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

-- |
-- Module      :  Phladiprelio.UniquenessPeriodsG
-- Copyright   :  (c) OleksandrZhabenko 2020-2023
-- License     :  MIT
-- Stability   :  Experimental
-- Maintainer  :  oleksandr.zhabenko@yahoo.com
--
-- Generalization of the uniqueness-periods and uniqueness-periods-general
-- packages functionality for small 'F.Foldable' data structures. Uses less dependencies.
--

{-# LANGUAGE BangPatterns #-}

module Phladiprelio.UniquenessPeriodsG (
  -- * List functions
  uniquenessPeriodsGG
  , uniquenessPeriodsG
  , uniquenessPeriodsGI8
  , diverse2GGL
  , diverse2GL
  , diverse2GLInt8
)  where

import GHC.Base
import GHC.Int
import Data.List hiding (foldr)
import GHC.Num ((-))
import Data.Tuple
import Data.Maybe (mapMaybe)
import qualified Data.Foldable as F

-- | A generalization of the uniquenessPeriods function of the @uniqueness-periods@ package.
uniquenessPeriodsGG :: (F.Foldable t1, F.Foldable t2, F.Foldable t3, Ord a) => t3 a -> t1 a -> t2 a -> [Int16]
uniquenessPeriodsGG sels whspss ws
 | F.null ws = []
 | otherwise = mapMaybe (helpGSel sels F.sum whspss) . unfoldr f $ ks
     where !ks = indexedL ws
           !vs = mapMaybe g ks
           g (x,y)
            | y `F.elem` whspss = Just x
            | otherwise = Nothing
           {-# INLINE g #-}
           f ys@(y:_) = let !idX0 = snd y in Just . (\(v2,v3) -> ((helpUPV3 vs [] .
                    map fst $ v2,snd . head $ v2),v3)) . partition (\(_,xs) -> xs == idX0) $ ys
           f _ = Nothing
{-# INLINE uniquenessPeriodsGG #-}

-- | A general variant of the diversity property. Use it in general case.
diverse2GGL :: (F.Foldable t1, F.Foldable t2, F.Foldable t3, Ord a) => t3 a -> t1 a -> t2 a -> Int16
diverse2GGL sels whspss = sum . uniquenessPeriodsGG sels whspss
{-# INLINE diverse2GGL #-}

-- | A variant of the 'diverse2GGL' function for 'Char'.
diverse2GL :: (F.Foldable t1, F.Foldable t2) => t1 Char -> t2 Char -> Int16
diverse2GL = diverse2GGL []
{-# INLINE diverse2GL #-}
--
-- | A variant for the 'uniquenessPeriodsGG' function for 'Char'.
uniquenessPeriodsG :: (F.Foldable t1, F.Foldable t2) => t1 Char -> t2 Char -> [Int16]
uniquenessPeriodsG = uniquenessPeriodsGG []
{-# INLINE uniquenessPeriodsG #-}

-- | A variant of the 'diverse2GGL' function for 'Int8'.
diverse2GLInt8 :: (F.Foldable t1, F.Foldable t2) => t1 Int8 -> t2 Int8 -> Int16
diverse2GLInt8 = diverse2GGL []
{-# INLINE diverse2GLInt8 #-}

-- | A variant for the 'uniquenessPeriodsGG' function for 'Int8'.
uniquenessPeriodsGI8 :: (F.Foldable t1, F.Foldable t2) => t1 Int8 -> t2 Int8 -> [Int16]
uniquenessPeriodsGI8 = uniquenessPeriodsGG []
{-# INLINE uniquenessPeriodsGI8 #-}

-- | The first and the third list arguments of numbers (if not empty) must be sorted in the ascending order.
helpUPV3 :: [Int16] -> [Int16] -> [Int16] -> [Int16]
helpUPV3 ks@(!z:zs) !acc ps@(!x:qs@(!y:_))
 | z < y && z > x = helpUPV3 zs ((y - x):acc) qs 
 | z < y = helpUPV3 zs acc ps
 | otherwise = helpUPV3 ks acc qs
helpUPV3 _ !acc _ = acc

indexedL :: F.Foldable t => t b -> [(Int16, b)]
indexedL = F.foldr f []
  where f x ((j,z):ys) = (j-1,x):(j,z):ys
        f x _ = [(1,x)]

helpG :: (Eq a, F.Foldable t1, F.Foldable t2) => (t1 b -> b) -> t2 a -> (t1 b, a) -> Maybe b
helpG h xs (ts, x)
  | F.null ts = Nothing
  | x `F.elem` xs = Nothing
  | otherwise = Just (h ts)
{-# INLINE helpG #-}

helpGSel :: (Eq a, F.Foldable t1, F.Foldable t2, F.Foldable t3) => t3 a -> (t1 b -> b) -> t2 a -> (t1 b, a) -> Maybe b
helpGSel sels h xs (ts, x)
  | F.null sels = helpG h xs (ts,x)
  | F.null ts = Nothing
  | x `F.elem` xs = Nothing
  | x `F.elem` sels = Just (h ts)
  | otherwise = Nothing
{-# INLINE helpGSel #-}