package Shape(Shape(..), emptyShape, joinShapes, joinManyShapes, mkRectangle, modShapeVis) where
import List
import Global
import Color

interface Shape =
    newPos :: XCoord -> YCoord -> Action
    color  :: Color

emptyShape :: Shape
emptyShape =
    interface Shape
        newPos x y = noAction
        color = cNone

joinShapes :: Shape -> Shape -> Shape
joinShapes s s' =
    interface Shape
        newPos x y = action { s.newPos x y; s'.newPos x y }
        color = s.color <|> s'.color

visCheck :: (Eq a) => Reg Bool -> a -> a -> a -> Action
visCheck r lo v hi = r := v /= hi && (v == lo || r)

mkRectangle :: XCoord -> XSize -> YCoord -> YSize -> Color -> Module Shape
mkRectangle xl xs yl ys col = do
    xVis :: Reg Bool <- mkRegU
    yVis :: Reg Bool <- mkRegU
    let xh = xl + xs
        yh = yl + ys
    return $
        interface Shape
            newPos x y =
                action
                    visCheck xVis xl x xh
                    visCheck yVis yl y yh
            color = if xVis && yVis then col else cNone

modShapeVis :: (Color -> Color) -> Shape -> Shape
modShapeVis f s =
    interface Shape
        newPos = s.newPos
        color = f s.color

joinManyShapes :: List Shape -> Shape
joinManyShapes = foldr joinShapes emptyShape