// Sources:
// https://iquilezles.org/articles/palettes/
// http://dev.thi.ng/gradients/

#[derive(Clone, Copy, PartialEq, Debug)]
pub struct ColorPalette {
    a: [f64; 3],
    b: [f64; 3],
    c: [f64; 3],
    d: [f64; 3],
}

impl ColorPalette {
    pub fn new(a: [f64; 3], b: [f64; 3], c: [f64; 3], d: [f64; 3]) -> Self {
        ColorPalette { a, b, c, d }
    }

    pub fn get(&self, t: f64) -> [f64; 3] {
        [
            (self.a[0] + self.b[0]*f64::cos(6.28318*(self.c[0]*t+self.d[0])))*255.0,
            (self.a[1] + self.b[1]*f64::cos(6.28318*(self.c[1]*t+self.d[1])))*255.0,
            (self.a[2] + self.b[2]*f64::cos(6.28318*(self.c[2]*t+self.d[2])))*255.0,
        ]
    }

    pub fn get_u8(&self, t: u8, n: u8) -> [f64; 3] {
        assert!(t>0, "t must be greater than zero!");
        assert!(n>0, "There cannot be zero points!");
        self.get((t-1) as f64 / (n-1) as f64)
    }
}

#[non_exhaustive]
pub struct Palettes;

#[allow(dead_code)]
impl Palettes {
    pub const RAINBOW: ColorPalette = ColorPalette {
        a: [0.500,0.500,0.500],
        b: [0.500,0.500,0.500],
        c: [0.800,0.800,0.800],
        d: [0.000,0.333,0.667],
    };
    pub const YELLOW_PINK: ColorPalette = ColorPalette {
        a: [0.500,0.500,0.320],
        b: [0.500,0.500,0.500],
        c: [0.100,0.500,0.360],
        d: [0.000,0.000,0.650],
    };
}