{-# OPTIONS_GHC -fno-warn-tabs #-}  -- Support tab indentation better, for a better default of no warning if tabs are used: https://dmitryfrank.com/articles/indent_with_tabs_align_with_spaces .
-- Enable warnings:
{-# OPTIONS_GHC -Wall -fno-warn-tabs #-}

-- Level/Utils.hs.

{-# LANGUAGE Haskell2010 #-}

module Immutaball.Share.Level.Utils
	(
		postprocessSol,
		miscProcessSol,
		transformSol,
		restoreSolTransformation,
		restoreSolTransformationSimple,
		mapcSolTransformationSimple,
		solErp,
		solErpdn
	) where

import Prelude ()
import Immutaball.Prelude

import Control.Lens

import Immutaball.Share.Level.Base
import Immutaball.Share.Math
import Immutaball.Share.Utils

-- | ‘transformSol’ and ‘miscProcessSol’.
postprocessSol :: Mat4 Double -> Sol -> Sol
postprocessSol m sol = miscProcessSol . transformSol m $ sol

-- | Replace ‘default’ with ‘mtrl/invisible’ for all mtrl paths.
miscProcessSol :: Sol -> Sol
miscProcessSol sol = sol &
	(solMv %~ fmap (mtrlF %~ (\p -> if' (p /= "default") p "mtrl/invisible")))

-- | Apply a transformation to all positions in a Sol.
--
-- TODO: apply transformation to path E orientation, which is a quaternion.
transformSol :: Mat4 Double -> Sol -> Sol
transformSol m sol = sol &
	(solVv %~ fmap (vertP %~ m4v3 m)) &
	(solPv %~ fmap (pathP %~ m4v3 m)) &
	-- TODO:
	--(solPv %~ fmap (pathE %~ (\q -> (\v -> (qasv4.~v) & q) . TODO . mv4 m . rotate3 . qToSr . (^.qasv4) $ q))) &  -- Convert quaternion rotation to rotation matrix, mat mul, then convert back to quaternion.
	(solHv %~ fmap (itemP %~ m4v3 m)) &
	(solZv %~ fmap (goalP %~ m4v3 m)) &
	(solJv %~ fmap (jumpP %~ m4v3 m)) &
	(solJv %~ fmap (jumpQ %~ m4v3 m)) &
	(solXv %~ fmap (swchP %~ m4v3 m)) &
	(solUv %~ fmap (ballP %~ m4v3 m)) &
	(solWv %~ fmap (viewP %~ m4v3 m)) &
	(solWv %~ fmap (viewQ %~ m4v3 m)) &
	id

-- | Invert mapc's swapping of y and z axes and negation to in terms I like to
-- think of in more; glFrustrum can be combined with a transformation.
restoreSolTransformation :: Mat4 Double
restoreSolTransformation = m3to4 $ restoreSolTransformationSimple

-- | Invert 'mapcSolTransformationSimple'.
--
-- This does not include the scaling by 1/64, which is preserved.
restoreSolTransformationSimple :: Mat3 Double
restoreSolTransformationSimple = Mat3 $ Vec3
	(Vec3 1.0 0.0 0.0   )
	(Vec3 0.0 0.0 (-1.0))
	(Vec3 0.0 1.0 0.0   )

mapcSolTransformationSimple :: Mat3 Double
mapcSolTransformationSimple = Mat3 $ Vec3
	(Vec3 1.0 0.0    0.0)
	(Vec3 0.0 0.0    1.0)
	(Vec3 0.0 (-1.0) 0.0)

-- | Convert a linear parameter (e.g. from 0 to 1) to a parameter that reflects
-- the sol ‘erp’ interpolation formula, for smooth paths.
solErp :: (Fractional a) => a -> a
solErp t = -2.0*t*t*t + 3.0*t*t

-- | Variant of 'solErp' that calculates derivatives an arbitrary number of times.
solErpdn :: (Fractional a) => Integer -> a -> a
solErpdn 0  t =  -2.0*t*t*t + 3.0*t*t  --  -2t^3 + 3t^2
solErpdn 1  t =  -6.0*t*t   + 6.0*t    --  -6t^2 + 6t
solErpdn 2  t = -12.0*t     + 6.0      -- -12t   + 6
solErpdn 3 _t = -12.0                  -- -12
solErpdn _ _t = 0