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/// An RGB color without gamma correction.
#[derive(Debug, Clone, Copy, PartialEq, PartialOrd)]
pub struct LinearRgb {
    /// Red (0 to 1).
    pub r: f32,
    /// Green (0 to 1).
    pub g: f32,
    /// Blue (0 to 1).
    pub b: f32,
}

impl crate::ColorSpace for LinearRgb {
    const BLACK: Self = Self {
        r: 0.0,
        g: 0.0,
        b: 0.0,
    };

    const WHITE: Self = Self {
        r: 1.0,
        g: 1.0,
        b: 1.0,
    };

    fn in_bounds(self) -> bool {
        crate::approx_in_range(self.r, 0.0..1.0)
            && crate::approx_in_range(self.g, 0.0..1.0)
            && crate::approx_in_range(self.b, 0.0..1.0)
    }
}

impl crate::CoreColorSpace for LinearRgb {
    fn from_xyz(xyz: crate::Xyz) -> Self {
        let r = xyz.x * 3.2404542 + xyz.y * -1.5371385 + xyz.z * -0.4985314;
        let g = xyz.x * -0.9692660 + xyz.y * 1.8760108 + xyz.z * 0.0415560;
        let b = xyz.x * 0.0556434 + xyz.y * -0.2040259 + xyz.z * 1.0572252;

        Self { r, g, b }
    }

    fn to_xyz(self) -> crate::Xyz {
        crate::Xyz {
            x: self.r * 0.4124564 + self.g * 0.3575761 + self.b * 0.1804375,
            y: self.r * 0.2126729 + self.g * 0.7151522 + self.b * 0.0721750,
            z: self.r * 0.0193339 + self.g * 0.1191920 + self.b * 0.9503041,
        }
    }
}

impl From<crate::Srgb> for LinearRgb {
    fn from(srgb: crate::Srgb) -> Self {
        let to_linear = |n: f32| {
            if n <= 0.04045 {
                n / 12.92
            } else {
                ((n + 0.055) / 1.055).powf(2.4)
            }
        };

        Self {
            r: to_linear(srgb.r),
            g: to_linear(srgb.g),
            b: to_linear(srgb.b),
        }
    }
}

impl crate::Hex for LinearRgb {
    fn components(self) -> (f32, f32, f32) {
        (self.r, self.g, self.b)
    }
}

#[cfg(test)]
#[test]
fn hex() {
    use crate::Hex;

    let rgb = LinearRgb {
        r: 1.0,
        g: 0.5,
        b: 0.0,
    };

    assert_eq!(rgb.hex(), 0xff8000);
}