module Exercise_7 where

import Data.List

{-WETT-}
filterFor :: Eq a => [(Integer,(a,a))] -> [(Integer,(a,a))]
filterFor [] = []
filterFor ((xc, (x1, x2)):xs) = case find (\(yc, (y1, y2)) -> y1 == x1 && y2 == x2 && yc <= xc) xs of
  Just _  -> filterFor xs
  Nothing -> (xc, (x1, x2)):filterFor xs

comp :: Eq b => [(Integer,(a,b))] -> [(Integer,(b,c))] -> [(Integer,(a,c))]
comp [] _ = []
comp _ [] = []
comp xs ys = [(xn + yn, (fst xt, snd yt)) | (xn, xt) <- xs, (yn, yt) <- ys, snd xt == fst yt]

trancl :: Eq a => [(Integer,(a,a))] -> [(Integer,(a,a))]
trancl xs = (reverse
        . filterFor2
        . sortBy (\(x1, _) (x2, _) -> compare x2 x1))
        (multipleComp xs [] [])


filterFor2 :: Eq a => [(Integer,(a,a))] -> [(Integer,(a,a))]
filterFor2 [] = []
filterFor2 ((xc, (x1, x2)):xs) = case find (\(yc, (y1, y2)) -> y1 == x1 && y2 == x2 && yc <= xc) xs of
  Just _  -> filterFor xs
  Nothing -> (xc, (x1, x2)):filterFor xs

multipleComp :: Eq a => [(Integer,(a,a))] -> [(Integer,(a,a))] -> [(Integer,(a,a))] -> [(Integer,(a,a))]
multipleComp [] _ _ = []
multipleComp xs [] _ = multipleComp xs xs xs
multipleComp xs ys acc = let currComp = filterFor3 acc (comp ys xs) in
      if currComp == [] then acc else (multipleComp xs currComp (acc ++ currComp))

filterFor3 :: Eq a => [(Integer,(a,a))] -> [(Integer,(a,a))] -> [(Integer,(a,a))]
filterFor3 _ [] = []
filterFor3 [] ys = ys
filterFor3 xs ((yc, (y1, y2)):ys) = case find (\(xc, (x1, x2)) -> x1 == y1 && x2 == y2 && xc < yc) xs of
  Just _ -> filterFor3 xs ys
  Nothing -> (yc, (y1, y2)):filterFor3 xs ys

{-TTEW-}