{- |
  Classes for generically handling bounding boxes, and things that possess bounding boxes.
-}

{-# LANGUAGE FlexibleContexts, MultiParamTypeClasses, TypeFamilies #-}

module Data.BoundingBox.Fancy where

import Data.Vector
import qualified Data.BoundingBox.Range as R
import qualified Data.BoundingBox.B1    as B1
import qualified Data.BoundingBox.B2    as B2
import qualified Data.BoundingBox.B3    as B3
import qualified Data.BoundingBox.B4    as B4

-- | Class for dealing with bounding boxes.
class HasSpace b => BoundingBox b where
  -- | Given two corner points, construct a bounding box containing them both. (You can use any two points, given in any order, provided that they are from /opposite/ corners.)
  bound_corners :: Point b -> Point b -> b

  -- | Given a list of points, construct a bounding box containing them all. (Throws an exception if the list is empty.)
  bound_points :: [Point b] -> b

  -- | Return a point containing the minimum values for all coordinates.
  min_point :: b -> Point b

  -- | Return a point containing the maximum values for all coordinates.
  max_point :: b -> Point b

  -- | Test whether a given point lies within a given bounding box.
  within_bounds :: Point b -> b -> Bool

  -- | Take the union of two bounding boxes. The result is a new bounding box that contains every point that the original pair of boxes contained, and probably some extra space as well.
  union :: b -> b -> b

  -- | Take the intersection of two bounding boxes. If the boxes do not overlap, return 'Nothing'. Otherwise return a bounding box containing only the points common to both original bounding boxes.
  isect :: b -> b -> Maybe b

  -- | Take the union of a list of bounding boxes. (This is more efficient than @foldr1 union@.)
  unions :: [b] -> b

instance HasSpace B1.BBox1 where
  type Point B1.BBox1 = Vector1

instance BoundingBox B1.BBox1 where
  bound_corners = B1.bound_corners
  bound_points  = B1.bound_points
  min_point     = B1.min_point
  max_point     = B1.max_point
  within_bounds = B1.within_bounds
  union         = B1.union
  isect         = B1.isect
  unions        = B1.unions

instance HasSpace B2.BBox2 where
  type Point B2.BBox2 = Vector2

instance BoundingBox B2.BBox2 where
  bound_corners = B2.bound_corners
  bound_points  = B2.bound_points
  min_point     = B2.min_point
  max_point     = B2.max_point
  within_bounds = B2.within_bounds
  union         = B2.union
  isect         = B2.isect
  unions        = B2.unions

instance HasSpace B3.BBox3 where
  type Point B3.BBox3 = Vector3

instance BoundingBox B3.BBox3 where
  bound_corners = B3.bound_corners
  bound_points  = B3.bound_points
  min_point     = B3.min_point
  max_point     = B3.max_point
  within_bounds = B3.within_bounds
  union         = B3.union
  isect         = B3.isect
  unions        = B3.unions

instance HasSpace B4.BBox4 where
  type Point B4.BBox4 = Vector4

instance BoundingBox B4.BBox4 where
  bound_corners = B4.bound_corners
  bound_points  = B4.bound_points
  min_point     = B4.min_point
  max_point     = B4.max_point
  within_bounds = B4.within_bounds
  union         = B4.union
  isect         = B4.isect
  unions        = B4.unions

-- | Get a 'R.Range' representing the extent of a bounding box on a specified coordinate axis.
axis_range :: (BoundingBox bbox, VectorAxis (Point bbox) axis) => axis -> bbox -> R.Range
axis_range axis bbox = R.Range (get_coord axis (min_point bbox)) (get_coord axis (max_point bbox))



-- | Class representing things that possess a bounding box.
class HasSpace x => HasBBox x where
  -- | Get an object's bounding box.
  get_bbox :: (BoundingBox b, Point b ~ Point x) => x -> b