module Bound where
import Geometry

import Control.Lens
import Streaming
import qualified Streaming.Prelude as S
import qualified Control.Foldl as L

boundPoints :: Stream (Of Point2) Identity () -> Maybe (Float,Float,Float,Float)
{-# INLINE boundPoints #-}
boundPoints = f . runIdentity . L.purely S.fold_ ((,,,) 
    <$> L.premap (^?! _2) L.maximum
    <*> L.premap (^?! _2) L.minimum
    <*> L.premap (^?! _1) L.maximum
    <*> L.premap (^?! _1) L.minimum
    )
  where
    f (mn,ms,me,mw) = (,,,) <$> mn <*> ms <*> me <*> mw