/*

 * // 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_atan2f, f_powf, f_sincosf};

/// Darktable UCS JCH ( Darktable Uniform Color Space )

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

pub struct DtUchJch {

    pub j: f32,

    pub c: f32,

    pub h: f32,

}

/// Darktable UCS HSB ( Darktable Uniform Color Space )

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

pub struct DtUchHsb {

    pub h: f32,

    pub s: f32,

    pub b: f32,

}

/// Darktable HCB ( Darktable Uniform Color Space )

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

pub struct DtUchHcb {

    pub h: f32,

    pub c: f32,

    pub b: f32,

}

const DT_UCS_L_STAR_RANGE: f32 = 2.098883786377;

#[inline]

fn y_to_dt_ucs_l_star(y: f32) -> f32 {

    let y_hat = f_powf(y, 0.631651345306265);

    DT_UCS_L_STAR_RANGE * y_hat / (y_hat + 1.12426773749357)

}

#[inline]

fn dt_ucs_l_star_to_y(x: f32) -> f32 {

    f_powf(

        1.12426773749357 * x / (DT_UCS_L_STAR_RANGE - x),

        1.5831518565279648,

    )

}

const L_WHITE: f32 = 0.98805060;

#[inline]

fn dt_ucs_luv_to_ucs_jch(

    l_star: f32,

    l_white: f32,

    u_star_prime: f32,

    v_star_prime: f32,

) -> DtUchJch {

    let m2: f32 = mlaf(u_star_prime * u_star_prime, v_star_prime, v_star_prime); // square of colorfulness M

    // should be JCH[0] = powf(L_star / L_white), cz) but we treat only the case where cz = 1

    let j = l_star / l_white;

    let c =

        15.932993652962535 * f_powf(l_star, 0.6523997524738018) * f_powf(m2, 0.6007557017508491)

            / l_white;

    let h = f_atan2f(v_star_prime, u_star_prime);

    DtUchJch::new(j, c, h)

}

#[inline]

fn dt_ucs_xy_to_uv(x: f32, y: f32) -> (f32, f32) {

    const X_C: [f32; 3] = [-0.783941002840055, 0.745273540913283, 0.318707282433486];

    const Y_C: [f32; 3] = [0.277512987809202, -0.205375866083878, 2.16743692732158];

    const BIAS: [f32; 3] = [0.153836578598858, -0.165478376301988, 0.291320554395942];

    let mut u_c = mlaf(mlaf(BIAS[0], Y_C[0], y), X_C[0], x);

    let mut v_c = mlaf(mlaf(BIAS[1], Y_C[1], y), X_C[1], x);

    let d_c = mlaf(mlaf(BIAS[2], Y_C[2], y), X_C[2], x);

    let div = if d_c >= 0.0 {

        d_c.max(f32::MIN)

    } else {

        d_c.min(-f32::MIN)

    };

    u_c /= div;

    v_c /= div;

    const STAR_C: [f32; 2] = [1.39656225667, 1.4513954287];

    const STAR_HF_C: [f32; 2] = [1.49217352929, 1.52488637914];

    let u_star = STAR_C[0] * u_c / (u_c.abs() + STAR_HF_C[0]);

    let v_star = STAR_C[1] * v_c / (v_c.abs() + STAR_HF_C[1]);

    // The following is equivalent to a 2D matrix product

    let u_star_prime = mlaf(-1.124983854323892 * u_star, -0.980483721769325, v_star);

    let v_star_prime = mlaf(1.86323315098672 * u_star, 1.971853092390862, v_star);

    (u_star_prime, v_star_prime)

}

impl DtUchJch {

    #[inline]

    pub fn new(j: f32, c: f32, h: f32) -> DtUchJch {

        DtUchJch { j, c, h }

    }

    #[inline]

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

        DtUchJch::from_xyy(xyz.to_xyy())

    }

    #[inline]

    pub fn to_xyz(&self) -> Xyz {

        let xyy = self.to_xyy();

        Xyz::from_xyy(xyy)

    }

    #[inline]

    pub fn from_xyy(xyy: [f32; 3]) -> DtUchJch {

        let l_star = y_to_dt_ucs_l_star(xyy[2]);

        // let l_white = y_to_dt_ucs_l_star(1.);

        let (u_star_prime, v_star_prime) = dt_ucs_xy_to_uv(xyy[0], xyy[1]);

        dt_ucs_luv_to_ucs_jch(l_star, L_WHITE, u_star_prime, v_star_prime)

    }

    #[inline]

    pub fn to_xyy(&self) -> [f32; 3] {

        // let l_white: f32 = y_to_dt_ucs_l_star(1.0);

        let l_star = (self.j * L_WHITE).max(0.0).min(2.09885);

        let m = if l_star != 0. {

            f_powf(

                self.c * L_WHITE / (15.932993652962535 * f_powf(l_star, 0.6523997524738018)),

                0.8322850678616855,

            )

        } else {

            0.

        };

        let sin_cos_h = f_sincosf(self.h);

        let u_star_prime = m * sin_cos_h.1;

        let v_star_prime = m * sin_cos_h.0;

        // The following is equivalent to a 2D matrix product

        let u_star = mlaf(

            -5.037522385190711 * u_star_prime,

            -2.504856328185843,

            v_star_prime,

        );

        let v_star = mlaf(

            4.760029407436461 * u_star_prime,

            2.874012963239247,

            v_star_prime,

        );

        const F: [f32; 2] = [1.39656225667, 1.4513954287];

        const HF: [f32; 2] = [1.49217352929, 1.52488637914];

        let u_c = -HF[0] * u_star / (u_star.abs() - F[0]);

        let v_c = -HF[1] * v_star / (v_star.abs() - F[1]);

        const U_C: [f32; 3] = [0.167171472114775, -0.150959086409163, 0.940254742367256];

        const V_C: [f32; 3] = [0.141299802443708, -0.155185060382272, 1.000000000000000];

        const BIAS: [f32; 3] = [

            -0.00801531300850582,

            -0.00843312433578007,

            -0.0256325967652889,

        ];

        let mut x = mlaf(mlaf(BIAS[0], V_C[0], v_c), U_C[0], u_c);

        let mut y = mlaf(mlaf(BIAS[1], V_C[1], v_c), U_C[1], u_c);

        let d = mlaf(mlaf(BIAS[2], V_C[2], v_c), U_C[2], u_c);

        let div = if d >= 0.0 {

            d.max(f32::MIN)

        } else {

            d.min(-f32::MIN)

        };

        x /= div;

        y /= div;

        let yb = dt_ucs_l_star_to_y(l_star);

        [x, y, yb]

    }

}

impl DtUchHsb {

    #[inline]

    pub fn new(h: f32, s: f32, b: f32) -> DtUchHsb {

        DtUchHsb { h, s, b }

    }

    #[inline]

    pub fn from_jch(jch: DtUchJch) -> DtUchHsb {

        let b = jch.j * (f_powf(jch.c, 1.33654221029386) + 1.);

        let s = if b > 0. { jch.c / b } else { 0. };

        let h = jch.h;

        DtUchHsb::new(h, s, b)

    }

    #[inline]

    pub fn to_jch(&self) -> DtUchJch {

        let h = self.h;

        let c = self.s * self.b;

        let j = self.b / (f_powf(c, 1.33654221029386) + 1.);

        DtUchJch::new(j, c, h)

    }

}

impl DtUchHcb {

    #[inline]

    pub fn new(h: f32, c: f32, b: f32) -> DtUchHcb {

        DtUchHcb { h, c, b }

    }

    #[inline]

    pub fn from_jch(jch: DtUchJch) -> DtUchHcb {

        let b = jch.j * (f_powf(jch.c, 1.33654221029386) + 1.);

        let c = jch.c;

        let h = jch.h;

        DtUchHcb::new(h, c, b)

    }

    #[inline]

    pub fn to_jch(&self) -> DtUchJch {

        let h = self.h;

        let c = self.c;

        let j = self.b / (f_powf(self.c, 1.33654221029386) + 1.);

        DtUchJch::new(j, c, h)

    }

}

#[cfg(test)]

mod tests {

    use super::*;

    #[test]

    fn test_darktable_ucs_jch() {

        let xyy = [0.4, 0.2, 0.5];

        let ucs = DtUchJch::from_xyy(xyy);

        let xyy_rev = ucs.to_xyy();

        assert!(

            (xyy[0] - xyy_rev[0]).abs() < 1e-5,

            "Expected {}, got {}",

            xyy[0],

            xyy_rev[0]

        );

        assert!(

            (xyy[1] - xyy_rev[1]).abs() < 1e-5,

            "Expected {}, got {}",

            xyy[1],

            xyy_rev[1]

        );

        assert!(

            (xyy[2] - xyy_rev[2]).abs() < 1e-5,

            "Expected {}, got {}",

            xyy[2],

            xyy_rev[2]

        );

    }

    #[test]

    fn test_darktable_hsb() {

        let jch = DtUchJch::new(0.3, 0.6, 0.4);

        let hsb = DtUchHsb::from_jch(jch);

        let r_jch = hsb.to_jch();

        assert!(

            (r_jch.j - jch.j).abs() < 1e-5,

            "Expected {}, got {}",

            jch.j,

            r_jch.j

        );

        assert!(

            (r_jch.c - jch.c).abs() < 1e-5,

            "Expected {}, got {}",

            jch.c,

            r_jch.c

        );

        assert!(

            (r_jch.h - jch.h).abs() < 1e-5,

            "Expected {}, got {}",

            jch.h,

            r_jch.h

        );

    }

    #[test]

    fn test_darktable_hcb() {

        let jch = DtUchJch::new(0.3, 0.6, 0.4);

        let hcb = DtUchHcb::from_jch(jch);

        let r_jch = hcb.to_jch();

        assert!(

            (r_jch.j - jch.j).abs() < 1e-5,

            "Expected {}, got {}",

            jch.j,

            r_jch.j

        );

        assert!(

            (r_jch.c - jch.c).abs() < 1e-5,

            "Expected {}, got {}",

            jch.c,

            r_jch.c

        );

        assert!(

            (r_jch.h - jch.h).abs() < 1e-5,

            "Expected {}, got {}",

            jch.h,

            r_jch.h

        );

    }

    #[test]

    fn test_darktable_ucs_jch_from_xyz() {

        let xyz = Xyz::new(0.4, 0.2, 0.5);

        let ucs = DtUchJch::from_xyz(xyz);

        let xyy_rev = ucs.to_xyz();

        assert!(

            (xyz.x - xyz.x).abs() < 1e-5,

            "Expected {}, got {}",

            xyz.x,

            xyy_rev.x

        );

        assert!(

            (xyz.y - xyz.y).abs() < 1e-5,

            "Expected {}, got {}",

            xyz.y,

            xyy_rev.y

        );

        assert!(

            (xyz.z - xyz.z).abs() < 1e-5,

            "Expected {}, got {}",

            xyz.z,

            xyy_rev.z

        );

    }

}