//!This module provides simple matrix operations on 3x3 matrix to aid in chromatic adaptation and
//!conversion calculations.

use float::Float;

use core::marker::PhantomData;

use {Component, Xyz};
use white_point::WhitePoint;
use rgb::{Primaries, Rgb, RgbSpace};
use encoding::Linear;
use convert::IntoColor;

///A 9 element array representing a 3x3 matrix
pub type Mat3<T> = [T; 9];

///Multiply the 3x3 matrix with the XYZ color
pub fn multiply_xyz<Swp: WhitePoint, Dwp: WhitePoint, T: Component + Float>(
    c: &Mat3<T>,
    f: &Xyz<Swp, T>,
) -> Xyz<Dwp, T> {
    Xyz {
        x: (c[0] * f.x) + (c[1] * f.y) + (c[2] * f.z),
        y: (c[3] * f.x) + (c[4] * f.y) + (c[5] * f.z),
        z: (c[6] * f.x) + (c[7] * f.y) + (c[8] * f.z),
        white_point: PhantomData,
    }
}
///Multiply the 3x3 matrix with the XYZ color into RGB color
pub fn multiply_xyz_to_rgb<S: RgbSpace, T: Component + Float>(
    c: &Mat3<T>,
    f: &Xyz<S::WhitePoint, T>,
) -> Rgb<Linear<S>, T> {
    Rgb {
        red: (c[0] * f.x) + (c[1] * f.y) + (c[2] * f.z),
        green: (c[3] * f.x) + (c[4] * f.y) + (c[5] * f.z),
        blue: (c[6] * f.x) + (c[7] * f.y) + (c[8] * f.z),
        standard: PhantomData,
    }
}
///Multiply the 3x3 matrix with the  RGB into XYZ color
pub fn multiply_rgb_to_xyz<S: RgbSpace, T: Component + Float>(
    c: &Mat3<T>,
    f: &Rgb<Linear<S>, T>,
) -> Xyz<S::WhitePoint, T> {
    Xyz {
        x: (c[0] * f.red) + (c[1] * f.green) + (c[2] * f.blue),
        y: (c[3] * f.red) + (c[4] * f.green) + (c[5] * f.blue),
        z: (c[6] * f.red) + (c[7] * f.green) + (c[8] * f.blue),
        white_point: PhantomData,
    }
}

///Multiply a 3x3 matrix with another 3x3 matrix
pub fn multiply_3x3<T: Float>(c: &Mat3<T>, f: &Mat3<T>) -> Mat3<T> {
    let mut out = [T::zero(); 9];
    out[0] = c[0] * f[0] + c[1] * f[3] + c[2] * f[6];
    out[1] = c[0] * f[1] + c[1] * f[4] + c[2] * f[7];
    out[2] = c[0] * f[2] + c[1] * f[5] + c[2] * f[8];

    out[3] = c[3] * f[0] + c[4] * f[3] + c[5] * f[6];
    out[4] = c[3] * f[1] + c[4] * f[4] + c[5] * f[7];
    out[5] = c[3] * f[2] + c[4] * f[5] + c[5] * f[8];

    out[6] = c[6] * f[0] + c[7] * f[3] + c[8] * f[6];
    out[7] = c[6] * f[1] + c[7] * f[4] + c[8] * f[7];
    out[8] = c[6] * f[2] + c[7] * f[5] + c[8] * f[8];

    out
}

///Invert a 3x3 matrix and panic if matrix is not invertable.
pub fn matrix_inverse<T: Float>(a: &Mat3<T>) -> Mat3<T> {
    let d0 = a[4] * a[8] - a[5] * a[7];
    let d1 = a[3] * a[8] - a[5] * a[6];
    let d2 = a[3] * a[7] - a[4] * a[6];
    let det = a[0] * d0 - a[1] * d1 + a[2] * d2;
    if !det.is_normal() {
        panic!("The given matrix is not invertible")
    }
    let d3 = a[1] * a[8] - a[2] * a[7];
    let d4 = a[0] * a[8] - a[2] * a[6];
    let d5 = a[0] * a[7] - a[1] * a[6];
    let d6 = a[1] * a[5] - a[2] * a[4];
    let d7 = a[0] * a[5] - a[2] * a[3];
    let d8 = a[0] * a[4] - a[1] * a[3];

    [
        d0 / det,
        -d3 / det,
        d6 / det,
        -d1 / det,
        d4 / det,
        -d7 / det,
        d2 / det,
        -d5 / det,
        d8 / det,
    ]
}

///Geneartes to Srgb to Xyz transformation matrix for the given white point
pub fn rgb_to_xyz_matrix<S: RgbSpace, T: Component + Float>() -> Mat3<T> {
    let r: Xyz<S::WhitePoint, T> = S::Primaries::red().into_xyz();
    let g: Xyz<S::WhitePoint, T> = S::Primaries::green().into_xyz();
    let b: Xyz<S::WhitePoint, T> = S::Primaries::blue().into_xyz();

    let mut transform_matrix = mat3_from_primaries(r, g, b);

    let s_matrix: Rgb<Linear<S>, T> = multiply_xyz_to_rgb(
        &matrix_inverse(&transform_matrix),
        &S::WhitePoint::get_xyz(),
    );
    transform_matrix[0] = transform_matrix[0] * s_matrix.red;
    transform_matrix[1] = transform_matrix[1] * s_matrix.green;
    transform_matrix[2] = transform_matrix[2] * s_matrix.blue;
    transform_matrix[3] = transform_matrix[3] * s_matrix.red;
    transform_matrix[4] = transform_matrix[4] * s_matrix.green;
    transform_matrix[5] = transform_matrix[5] * s_matrix.blue;
    transform_matrix[6] = transform_matrix[6] * s_matrix.red;
    transform_matrix[7] = transform_matrix[7] * s_matrix.green;
    transform_matrix[8] = transform_matrix[8] * s_matrix.blue;

    transform_matrix
}

#[cfg_attr(rustfmt, rustfmt_skip)]
fn mat3_from_primaries<T: Component + Float, Wp: WhitePoint>(r: Xyz<Wp, T>, g: Xyz<Wp, T>, b: Xyz<Wp, T>) -> Mat3<T> {
    [
        r.x, g.x, b.x,
        r.y, g.y, b.y,
        r.z, g.z, b.z,
    ]
}

#[cfg(test)]
mod test {
    use Xyz;
    use rgb::Rgb;
    use encoding::{Linear, Srgb};
    use chromatic_adaptation::AdaptInto;
    use white_point::D50;
    use super::{matrix_inverse, multiply_xyz, rgb_to_xyz_matrix, multiply_3x3};

    #[test]
    fn matrix_multiply_3x3() {
        let inp1 = [1.0, 2.0, 3.0, 3.0, 2.0, 1.0, 2.0, 1.0, 3.0];
        let inp2 = [4.0, 5.0, 6.0, 6.0, 5.0, 4.0, 4.0, 6.0, 5.0];
        let expected = [28.0, 33.0, 29.0, 28.0, 31.0, 31.0, 26.0, 33.0, 31.0];

        let computed = multiply_3x3(&inp1, &inp2);
        assert_eq!(expected, computed)
    }

    #[test]
    fn matrix_multiply_xyz() {
        let inp1 = [0.1, 0.2, 0.3, 0.3, 0.2, 0.1, 0.2, 0.1, 0.3];
        let inp2 = Xyz::new(0.4, 0.6, 0.8);

        let expected = Xyz::new(0.4, 0.32, 0.38);

        let computed = multiply_xyz(&inp1, &inp2);
        assert_relative_eq!(expected, computed)
    }

    #[test]
    fn matrix_inverse_check_1() {
        let input: [f64; 9] = [3.0, 0.0, 2.0, 2.0, 0.0, -2.0, 0.0, 1.0, 1.0];

        let expected: [f64; 9] = [0.2, 0.2, 0.0, -0.2, 0.3, 1.0, 0.2, -0.3, 0.0];
        let computed = matrix_inverse(&input);
        assert_eq!(expected, computed);
    }
    #[test]
    fn matrix_inverse_check_2() {
        let input: [f64; 9] = [1.0, 0.0, 1.0, 0.0, 2.0, 1.0, 1.0, 1.0, 1.0];

        let expected: [f64; 9] = [-1.0, -1.0, 2.0, -1.0, 0.0, 1.0, 2.0, 1.0, -2.0];
        let computed = matrix_inverse(&input);
        assert_eq!(expected, computed);
    }
    #[test]
    #[should_panic]
    fn matrix_inverse_panic() {
        let input: [f64; 9] = [1.0, 0.0, 0.0, 2.0, 0.0, 0.0, -4.0, 6.0, 1.0];
        matrix_inverse(&input);
    }

    #[cfg_attr(rustfmt, rustfmt_skip)]
    #[test]
    fn d65_rgb_conversion_matrix() {
        let expected = [
            0.4124564, 0.3575761, 0.1804375,
            0.2126729, 0.7151522, 0.0721750,
            0.0193339, 0.1191920, 0.9503041
        ];
        let computed = rgb_to_xyz_matrix::<Srgb, f64>();
        for (e, c) in expected.iter().zip(computed.iter()) {
            assert_relative_eq!(e, c, epsilon = 0.000001)
        }
    }

    #[test]
    fn d65_to_d50() {
        let input: Rgb<Linear<Srgb>> = Rgb::new(1.0, 1.0, 1.0);
        let expected: Rgb<Linear<(Srgb, D50)>> = Rgb::new(1.0, 1.0, 1.0);

        let computed: Rgb<Linear<(Srgb, D50)>> = input.adapt_into();
        assert_relative_eq!(expected, computed, epsilon = 0.000001);
    }
}