-- | Sets of places
module PlaceSet
    ( PlaceSet
    , listToPlaceSet
    , placeSetToList
    , singleton
    , empty
    , nullPS
    , insert
    , delete
    , member
    , size
    , (\\)
    , unions
    , intersection
    , disjunct
    , isSubsetOf

    -- * Useful functions
    , places

    ) where

import Place

import qualified Data.IntSet as S

-------------

-- | Set of places.
type PlaceSet = S.IntSet

listToPlaceSet :: [Place] -> PlaceSet
listToPlaceSet = S.fromList . map hashPlace

placeSetToList :: PlaceSet -> [Place]
placeSetToList = map unHashPlace . S.toList

singleton :: Place -> PlaceSet
singleton = S.singleton . hashPlace

-- | The empty PlaceSet.
empty :: PlaceSet
empty = S.empty

insert :: Place -> PlaceSet -> PlaceSet
insert p ps = S.insert (hashPlace p) ps

delete :: Place -> PlaceSet -> PlaceSet
delete p ps = S.delete (hashPlace p) ps

-- | True if the PlaceSet is empty.
nullPS :: PlaceSet -> Bool
nullPS = S.null

member :: Place -> PlaceSet -> Bool
member p = S.member (hashPlace p)

size :: PlaceSet -> Int
size = S.size

-- | Difference.
(\\) :: PlaceSet -> PlaceSet -> PlaceSet
(\\) = (S.\\)

unions :: [PlaceSet] -> PlaceSet
unions = S.unions

disjunct :: PlaceSet -> PlaceSet -> Bool
disjunct a b = S.null (S.intersection a b)

intersection :: PlaceSet -> PlaceSet -> PlaceSet
intersection = S.intersection

isSubsetOf :: PlaceSet -> PlaceSet -> Bool
isSubsetOf = S.isSubsetOf

----------------------

-- | All places at a board.
places :: Size -> PlaceSet
places (xS, yS) = listToPlaceSet [p | x<-[1..xS], p <- placesInAColumn x (1, yS)]