{-# LANGUAGE DeriveDataTypeable, ScopedTypeVariables #-}
-----------------------------------------------------------------------------
-- |
-- Module      :  Linear.V4
-- Copyright   :  (C) 2012-2013 Edward Kmett,
-- License     :  BSD-style (see the file LICENSE)
--
-- Maintainer  :  Edward Kmett <ekmett@gmail.com>
-- Stability   :  experimental
-- Portability :  non-portable
--
-- 4-D Vectors
----------------------------------------------------------------------------
module Linear.V4
  ( V4(..)
  , vector, point
  , R2(..)
  , R3(..)
  , R4(..)
  ) where

import Control.Applicative
import Control.Lens
import Data.Data
import Data.Distributive
import Data.Foldable
import Data.Monoid
import Foreign.Ptr (castPtr)
import Foreign.Storable (Storable(..))
import GHC.Arr (Ix(..))
import Linear.Epsilon
import Linear.Metric
import Linear.V2
import Linear.V3

-- | A 4-dimensional vector.
data V4 a = V4 a a a a deriving (Eq,Ord,Show,Read,Data,Typeable)

instance Functor V4 where
  fmap f (V4 a b c d) = V4 (f a) (f b) (f c) (f d)
  {-# INLINE fmap #-}
  a <$ _ = V4 a a a a
  {-# INLINE (<$) #-}

instance Foldable V4 where
  foldMap f (V4 a b c d) = f a `mappend` f b `mappend` f c `mappend` f d
  {-# INLINE foldMap #-}

instance Traversable V4 where
  traverse f (V4 a b c d) = V4 <$> f a <*> f b <*> f c <*> f d
  {-# INLINE traverse #-}

instance Applicative V4 where
  pure a = V4 a a a a
  {-# INLINE pure #-}
  V4 a b c d <*> V4 e f g h = V4 (a e) (b f) (c g) (d h)
  {-# INLINE (<*>) #-}

instance Monad V4 where
  return a = V4 a a a a
  {-# INLINE return #-}
  (>>=) = bindRep
  {-# INLINE (>>=) #-}

instance Num a => Num (V4 a) where
  (+) = liftA2 (+)
  {-# INLINE (+) #-}
  (*) = liftA2 (*)
  {-# INLINE (-) #-}
  (-) = liftA2 (-)
  {-# INLINE (*) #-}
  negate = fmap negate
  {-# INLINE negate #-}
  abs = fmap abs
  {-# INLINE abs #-}
  signum = fmap signum
  {-# INLINE signum #-}
  fromInteger = pure . fromInteger
  {-# INLINE fromInteger #-}

instance Fractional a => Fractional (V4 a) where
  recip = fmap recip
  {-# INLINE recip #-}
  (/) = liftA2 (/)
  {-# INLINE (/) #-}
  fromRational = pure . fromRational
  {-# INLINE fromRational #-}

instance Metric V4 where
  dot (V4 a b c d) (V4 e f g h) = a * e + b * f + c * g + d * h
  {-# INLINE dot #-}

instance Distributive V4 where
  distribute f = V4 (fmap (^._x) f) (fmap (^._y) f) (fmap (^._z) f) (fmap (^._w) f)
  {-# INLINE distribute #-}

-- | A space that distinguishes orthogonal basis vectors '_x', '_y', '_z', '_w'. (It may have more.)
class R3 t => R4 t where
  _w :: Functor f => (a -> f a) -> t a -> f (t a)
  _xyzw :: Functor f => (V4 a -> f (V4 a)) -> t a -> f (t a)

instance R2 V4 where
  _x f (V4 a b c d) = (\a' -> V4 a' b c d) <$> f a
  {-# INLINE _x #-}
  _y f (V4 a b c d) = (\b' -> V4 a b' c d) <$> f b
  {-# INLINE _y #-}
  _xy f (V4 a b c d) = (\(V2 a' b') -> V4 a' b' c d) <$> f (V2 a b)
  {-# INLINE _xy #-}

instance R3 V4 where
  _z f (V4 a b c d) = (\c' -> V4 a b c' d) <$> f c
  {-# INLINE _z #-}
  _xyz f (V4 a b c d) = (\(V3 a' b' c') -> V4 a' b' c' d) <$> f (V3 a b c)
  {-# INLINE _xyz #-}

instance R4 V4 where
  _w f (V4 a b c d) = V4 a b c <$> f d
  {-# INLINE _w #-}
  _xyzw = id
  {-# INLINE _xyzw #-}

instance Representable V4 where
  rep f = V4 (f _x) (f _y) (f _z) (f _w)
  {-# INLINE rep #-}

instance forall a. Storable a => Storable (V4 a) where
  sizeOf _ = 4 * sizeOf (undefined::a)
  {-# INLINE sizeOf #-}
  alignment _ = alignment (undefined::a)
  {-# INLINE alignment #-}
  poke ptr (V4 x y z w) = do poke ptr' x
                             pokeElemOff ptr' 1 y
                             pokeElemOff ptr' 2 z
                             pokeElemOff ptr' 3 w
    where ptr' = castPtr ptr
  {-# INLINE poke #-}
  peek ptr = V4 <$> peek ptr' <*> peekElemOff ptr' 1
                <*> peekElemOff ptr' 2 <*> peekElemOff ptr' 3
    where ptr' = castPtr ptr
  {-# INLINE peek #-}

-- | Convert a 3-dimensional affine vector into a 4-dimensional homogeneous vector.
vector :: Num a => V3 a -> V4 a
vector (V3 a b c) = V4 a b c 0
{-# INLINE vector #-}

-- | Convert a 3-dimensional affine point into a 4-dimensional homogeneous vector.
point :: Num a => V3 a -> V4 a
point (V3 a b c) = V4 a b c 1
{-# INLINE point #-}

instance Epsilon a => Epsilon (V4 a) where
  nearZero = nearZero . quadrance
  {-# INLINE nearZero #-}

instance Ix a => Ix (V4 a) where
  {-# SPECIALISE instance Ix (V4 Int) #-}

  range (V4 l1 l2 l3 l4,V4 u1 u2 u3 u4) =
    [V4 i1 i2 i3 i4 | i1 <- range (l1,u1)
                    , i2 <- range (l2,u2)
                    , i3 <- range (l3,u3)
                    , i4 <- range (l4,u4)
                    ]
  {-# INLINE range #-}

  unsafeIndex (V4 l1 l2 l3 l4,V4 u1 u2 u3 u4) (V4 i1 i2 i3 i4) =
    unsafeIndex (l4,u4) i4 + unsafeRangeSize (l4,u4) * (
    unsafeIndex (l3,u3) i3 + unsafeRangeSize (l3,u3) * (
    unsafeIndex (l2,u2) i2 + unsafeRangeSize (l2,u2) * (
    unsafeIndex (l1,u1) i1)))
  {-# INLINE unsafeIndex #-}

  inRange (V4 l1 l2 l3 l4,V4 u1 u2 u3 u4) (V4 i1 i2 i3 i4) =
    inRange (l1,u1) i1 && inRange (l2,u2) i2 &&
    inRange (l3,u3) i3 && inRange (l4,u4) i4
  {-# INLINE inRange #-}