/*

 * // Copyright (c) Radzivon Bartoshyk 6/2025. All rights reserved.

 * //

 * // Redistribution and use in source and binary forms, with or without modification,

 * // are permitted provided that the following conditions are met:

 * //

 * // 1.  Redistributions of source code must retain the above copyright notice, this

 * // list of conditions and the following disclaimer.

 * //

 * // 2.  Redistributions in binary form must reproduce the above copyright notice,

 * // this list of conditions and the following disclaimer in the documentation

 * // and/or other materials provided with the distribution.

 * //

 * // 3.  Neither the name of the copyright holder nor the names of its

 * // contributors may be used to endorse or promote products derived from

 * // this software without specific prior written permission.

 * //

 * // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

 * // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

 * // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE

 * // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

 * // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER

 * // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,

 * // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

use crate::Xyz;

use crate::mlaf::mlaf;

use pxfm::f_cbrtf;

#[inline]

fn srlab2_gamma(x: f32) -> f32 {

    if x <= 216. / 24389. {

        x * (24389. / 2700.)

    } else {

        1.16 * f_cbrtf(x) - 0.16

    }

}

#[inline]

fn srlab2_linearize(x: f32) -> f32 {

    if x <= 0.08 {

        x * (2700.0 / 24389.0)

    } else {

        let zx = (x + 0.16) / 1.16;

        zx * zx * zx

    }

}

#[derive(Copy, Clone, Debug, Default, PartialOrd, PartialEq)]

pub struct Srlab2 {

    pub l: f32,

    pub a: f32,

    pub b: f32,

}

impl Srlab2 {

    #[inline]

    pub const fn new(l: f32, a: f32, b: f32) -> Srlab2 {

        Srlab2 { l, a, b }

    }

    #[inline]

    pub fn from_xyz(xyz: Xyz) -> Srlab2 {

        let lx = srlab2_gamma(xyz.x);

        let ly = srlab2_gamma(xyz.y);

        let lz = srlab2_gamma(xyz.z);

        let l = mlaf(mlaf(0.629054 * ly, -0.000008, lz), 0.37095, lx);

        let a = mlaf(mlaf(6.634684 * lx, -7.505078, ly), 0.870328, lz);

        let b = mlaf(mlaf(0.639569 * lx, 1.084576, ly), -1.724152, lz);

        Srlab2 { l, a, b }

    }

    #[inline]

    pub fn to_xyz(&self) -> Xyz {

        let x = mlaf(mlaf(self.l, 0.09041272, self.a), 0.045634452, self.b);

        let y = mlaf(mlaf(self.l, -0.05331593, self.a), -0.026917785, self.b);

        let z = mlaf(self.l, -0.58, self.b);

        let lx = srlab2_linearize(x);

        let ly = srlab2_linearize(y);

        let lz = srlab2_linearize(z);

        Xyz::new(lx, ly, lz)

    }

}

#[cfg(test)]

mod tests {

    use super::*;

    #[test]

    fn test_srlab2() {

        let xyz = Xyz::new(0.3, 0.65, 0.66);

        let srlab2 = Srlab2::from_xyz(xyz);

        let r_xyz = srlab2.to_xyz();

        assert!((r_xyz.x - xyz.x).abs() < 1e-5);

        assert!((r_xyz.y - xyz.y).abs() < 1e-5);

        assert!((r_xyz.z - xyz.z).abs() < 1e-5);

    }

}