{-# OPTIONS_GHC -fno-warn-orphans #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE UndecidableInstances #-}
{-# LANGUAGE UnicodeSyntax #-}
--------------------------------------------------------------------------------
-- |
-- Module      :  Data.Geometry.Line
-- Copyright   :  (C) Frank Staals
-- License     :  see the LICENSE file
-- Maintainer  :  Frank Staals
--
-- \(d\)-dimensional lines.
--
--------------------------------------------------------------------------------
module Data.Geometry.Line( module Data.Geometry.Line.Internal
                         ) where

import           Control.Lens
import           Data.Ext
import           Data.Geometry.Boundary
import           Data.Geometry.Box
import           Data.Geometry.Line.Internal
import           Data.Geometry.LineSegment
import           Data.Geometry.Point
import           Data.Geometry.Properties
import           Data.Geometry.SubLine
import           Data.Geometry.Transformation
import           Data.Geometry.Vector
import qualified Data.List as L
import           Data.Maybe (mapMaybe)
import           Data.Proxy
import           Data.UnBounded
import           Data.Vinyl.CoRec
import           Data.Vinyl.Core
import           Data.Vinyl.Lens
import           GHC.TypeLits

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


-- | Lines are transformable, via line segments
instance (Fractional r, Arity d, Arity (d + 1)) => IsTransformable (Line d r) where
  transformBy t = supportingLine . transformPointFunctor t . toLineSegment'
    where
      toLineSegment' :: (Num r, Arity d) => Line d r -> LineSegment d () r
      toLineSegment' = toLineSegment

type instance IntersectionOf (Point d r) (Line d r) = [NoIntersection, Point d r]


instance (Eq r, Fractional r, Arity d) => (Point d r) `IsIntersectableWith` (Line d r) where
  nonEmptyIntersection = defaultNonEmptyIntersection
  intersects = onLine
  p `intersect` l | p `intersects` l = coRec p
                  | otherwise        = coRec NoIntersection

instance {-# OVERLAPPING #-} (Ord r, Num r)
        => (Point 2 r) `IsIntersectableWith` (Line 2 r) where
  nonEmptyIntersection = defaultNonEmptyIntersection
  intersects = onLine2
  p `intersect` l | p `intersects` l = coRec p
                  | otherwise        = coRec NoIntersection


type instance IntersectionOf (Line 2 r) (Boundary (Rectangle p r)) =
  [ NoIntersection, Point 2 r, (Point 2 r, Point 2 r) , LineSegment 2 () r]


instance (Ord r, Fractional r)
         => (Line 2 r) `IsIntersectableWith` (Boundary (Rectangle p r)) where
  nonEmptyIntersection = defaultNonEmptyIntersection

  line' `intersect` (Boundary rect)  = case asAP segP of
      [sl'] -> case fromUnbounded sl' of
        Nothing   -> error "intersect: line x boundary rect; unbounded line? absurd"
        Just sl'' -> coRec $ sl''^.re _SubLine
      []    -> case nub' $ asAP pointP of
        [p]   -> coRec p
        [p,q] -> coRec (p,q)
        _     -> coRec NoIntersection
      _     -> error "intersect; line x boundary rect; absurd"
    where
      (t,r,b,l) = sides' rect
      ints = map (\s -> sl `intersect` toSL s) [t,r,b,l]

      nub' = map L.head . L.group . L.sort

      sl = fromLine line'
      -- wrap a segment into an potentially unbounded subline
      toSL  :: LineSegment 2 p r -> SubLine 2 () (UnBounded r) r
      toSL s = s^._SubLine.re _unBounded.to dropExtra

      asAP  :: forall proxy t. (t ∈ IntersectionOf (SubLine 2 () (UnBounded r) r)
                                                   (SubLine 2 () (UnBounded r) r))
             => proxy t -> [t]
      asAP _ = mapMaybe (asA @t) ints

      segP   = Proxy :: Proxy (SubLine 2 () (UnBounded r) r)
      pointP = Proxy :: Proxy (Point 2 r)


type instance IntersectionOf (Line 2 r) (Rectangle p r) =
  [ NoIntersection, Point 2 r, LineSegment 2 () r]


instance (Ord r, Fractional r)
         => (Line 2 r) `IsIntersectableWith` (Rectangle p r) where
  nonEmptyIntersection = defaultNonEmptyIntersection

  line' `intersect` rect  = match (line' `intersect` (Boundary rect)) $
       (H $ \NoIntersection -> coRec NoIntersection)
    :& (H $ \p@(Point2 _ _) -> coRec p)
    :& (H $ \(p,q)          -> coRec $ ClosedLineSegment (ext p) (ext q))
    :& (H $ \s              -> coRec s)
    :& RNil