use rand::{self, Rng};

use crate::vec3::Vec3;

// HSV values in [0..1]
// returns [r, g, b] values from 0 to 255
//From https://martin.ankerl.com/2009/12/09/how-to-create-random-colors-programmatically/
pub fn hsv_to_rgb(h: f32, s: f32, v: f32) -> Vec3 {
    let h_i = (h * 6.) as i32;
    let f = h * 6. - h_i as f32;
    let p = v * (1. - s);
    let q = v * (1. - f * s);
    let t = v * (1. - (1. - f) * s);
    match h_i {
        0 => Vec3::new(v, t, p),
        1 => Vec3::new(q, v, p),
        2 => Vec3::new(p, v, t),
        3 => Vec3::new(p, q, v),
        4 => Vec3::new(t, p, v),
        5 => Vec3::new(v, p, q),
        _ => panic!("Unknown H value {}", h_i),
    }
}

pub fn generate_rainbow(num: usize) -> Vec<Vec3> {
    (0..num)
        .map(|n| {
            let h = n as f32 / num as f32;
            hsv_to_rgb(h, 0.99, 0.99)
        })
        .collect()
}
pub fn generate_palette(num: usize) -> Vec<Vec3> {
    let mut rng = rand::thread_rng();
    let mut random = || rng.gen();
    // use golden ratio
    let golden_ratio_conjugate = 0.618_034;
    let mut h = random();
    (0..num)
        .map(|_| {
            h += golden_ratio_conjugate;
            h %= 1.0;
            hsv_to_rgb(h, 0.99, 0.99)
        })
        .collect()
}