-- This module provides basic algebra with 2d-vectors and geomtric shapes
-- Copyright (C) 2015, Sebastian Jordan

-- This program is free software: you can redistribute it and/or modify
-- it under the terms of the GNU General Public License as published by
-- the Free Software Foundation, either version 3 of the License, or
-- (at your option) any later version.

-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-- GNU General Public License for more details.

-- You should have received a copy of the GNU General Public License
-- along with this program.  If not, see <http://www.gnu.org/licenses/>.

module Geom2d.Shape
    ( Shape
    , Spatial (..)
    , circle
    , rectangle
    , convexHull
    , centerPoint
    )

where

import Geom2d.Point
import Geom2d.Rotation
import Geom2d.Shape.Internal
import Geom2d.Translate

circle :: Num a => p a -> a -> Shape p a
circle m r = ShapeCircle $ mkCircleInt m r

rectangle :: (Translate p, Eq a, RealFloat a, Point p, Rotation p) =>
             p a -> a -> a -> Maybe (Shape p a)
rectangle m a b = ShapePolygon <$> rectangleInt m a b

convexHull :: (Num (p a), Fractional a, Ord a, Scale p, Point p) =>
              [p a] -> Maybe (Shape p a)
convexHull list = ShapePolygon <$> convexHull' list

centerPoint :: (Fractional a, Scale p, Num (p a)) => Shape p a -> p a
centerPoint (ShapeCircle (Circle m _)) = m
centerPoint (ShapePolygon (Polygon m vs)) =
  let n = length vs
  in m + scale (1/fromIntegral n) (sum vs)