use memoffset::offset_of;
use ash::vk;
use rand::{thread_rng, distributions::{Distribution, Uniform}};
use cgmath::{InnerSpace, Vector2, Vector4};
use num::traits::FloatConst;
use crate::utility::constants::*;
use std::f32::consts::PI;

const PARTICLE_COUNT: i32 = 1000;

#[repr(C)]
#[derive(Clone, Debug, Copy)]
pub struct Particle {
    pos: Vector2<f32>,
    vel: Vector2<f32>,
    color: Vector4<f32>,
}

impl Particle {
    pub fn gen() -> Vec<Self> {
        let mut res = vec![];
 
        let between = Uniform::from(0.0..1.0);
        let mut rng = thread_rng();

        for i in 0..PARTICLE_COUNT {
            let r = (between.sample(&mut rng) as f32).sqrt();
            let theta = between.sample(&mut rng) * 2.0 * PI;
            let x = r * theta.cos() * WINDOW_HEIGHT as f32 * WINDOW_WIDTH as f32;
            let y = r * theta.sin();
            res.push(
                Particle {
                    pos: Vector2::new(x, y),
                    vel: Vector2::new(x, y).normalize() * 0.00025,
                    color: Vector4::new(between.sample(&mut rng), between.sample(&mut rng), between.sample(&mut rng), 1.0),
                }
            )
        }
        res
    }
}

#[repr(C)]
#[derive(Clone, Debug, Copy)]
pub struct Vertex {
    pos: [f32; 2],
    color: [f32; 3],
}

impl Vertex {
    pub fn get_binding_description() -> [vk::VertexInputBindingDescription; 1] {
        [vk::VertexInputBindingDescription {
            binding: 0,
            stride: std::mem::size_of::<Vertex>() as u32,
            input_rate: vk::VertexInputRate::VERTEX,
        }]
    }

    pub fn get_attribute_descriptions() -> [vk::VertexInputAttributeDescription; 2] {
        [
            vk::VertexInputAttributeDescription {
                binding: 0,
                location: 0,
                format: vk::Format::R32G32_SFLOAT,
                offset: offset_of!(Vertex, pos) as u32,
            },
            vk::VertexInputAttributeDescription {
                binding: 0,
                location: 1,
                format: vk::Format::R32G32B32_SFLOAT,
                offset: offset_of!(Vertex, color) as u32,
            },
        ]
    }
}

pub const TRI_VERT_DATA: [Vertex; 3] = [
    Vertex {
        pos: [0.0, -0.5],
        color: [1.0, 1.0, 1.0],
    },
    Vertex {
        pos: [0.5, 0.5],
        color: [0.0, 1.0, 0.0],
    },
    Vertex {
        pos: [-0.5, 0.5],
        color: [0.0, 0.0, 1.0],
    },
];