{-# LANGUAGE Haskell2010
    , GeneralizedNewtypeDeriving
    , DeriveDataTypeable
 #-}
{-# OPTIONS
    -Wall
    -fno-warn-missing-signatures
 #-}

module Utils where

import Data.Strings

import Data.List (foldl')

import Data.Set (Set)
import qualified Data.Set as Set
import qualified Data.Bimap as Bimap

(>>>) = flip (.)

intersections :: Ord a => [Set a] -> Set a
intersections sets = case sets of
    [] -> Set.empty
    [x] -> x
    (x:xs) -> foldl' Set.intersection x xs

uneither :: Either a a -> a
uneither = either id id

-- Following 20 lines: Functions for managing a Bimap
-- such that it works with case insensitive string.
--
-- TODO: Factor this out `plus` use the case-insensitive package.
--       Those functions x... should be made into their own
--       datatype (Something like CISBimap or
--       BimapWithGenericComparisonFunction or ...)

newtype CaseInsensitiveString = CIS String
    deriving Show

instance Eq CaseInsensitiveString where
    (CIS a) == (CIS b) = strToLower a == strToLower b

instance Ord CaseInsensitiveString where
    (CIS a) <= (CIS b) = strToLower a <= strToLower b

xToString (CIS s) = s

xEmpty      = Bimap.empty
xInsert k v = Bimap.insert (CIS k) (CIS v)
xMemberR k  = Bimap.memberR (CIS k)

xLookup :: Bimap.Bimap CaseInsensitiveString CaseInsensitiveString -> String -> Maybe String
xLookup m   = maybe Nothing (Just . xToString) . (flip Bimap.lookup m) . CIS

xLookupR :: Bimap.Bimap CaseInsensitiveString CaseInsensitiveString -> String -> Maybe String
xLookupR m   = maybe Nothing (Just . xToString) . (flip Bimap.lookupR m) . CIS

xFromList   = Bimap.fromList . map (\(a, b) -> (CIS a, CIS b))
xToList     = map (\(a, b) -> (xToString a, xToString b)) . Bimap.toList
xKeysR      = map xToString . Bimap.keysR
xKeys       = map xToString . Bimap.keys
xSize       = Bimap.size

-- end todo