#![forbid(unsafe_code)]
use crate::linear_algebra::{ Vec2, Vec3, Mat4, Transformation };

use std::mem::size_of;
use vulkanalia::vk::{ self, HasBuilder };


pub static VERTICES: [Vertex<f32>; 4] = [
  Vertex::new(Vec2::new(-0.5, -0.5), Vec3::new(1.0, 0.0, 0.0),
              Vec2::new(1.0, 0.0)),
  Vertex::new(Vec2::new( 0.5, -0.5), Vec3::new(0.0, 1.0, 0.0),
              Vec2::new(0.0, 0.0)),
  Vertex::new(Vec2::new( 0.5,  0.5), Vec3::new(0.0, 0.0, 1.0),
              Vec2::new(0.0, 1.0)),
  Vertex::new(Vec2::new(-0.5,  0.5), Vec3::new(1.0, 1.0, 1.0),
              Vec2::new(1.0, 1.0)),
];

pub const INDICES: &[u16] = &[0, 1, 2, 2, 3, 0];


#[repr(C)]
#[derive(Clone, Debug)]
pub struct Vertex<T: Copy> {
  pub position: Vec2<T>,
  pub color: Vec3<T>,
  pub texture_coordinates: Vec2<T>,
}

#[repr(C)]
#[derive(Clone, Debug)]
pub struct UniformBlock<T: Copy> {
  pub scale: Vec3<T>,
  pub model: Transformation<T>,
  pub view: Transformation<T>,
  pub projection: Mat4<T>,
}

impl<T: Copy> Vertex<T> {
  const fn new(position: Vec2<T>, color: Vec3<T>,
               texture_coordinates: Vec2<T>)
      -> Self
  {
    Self { position, color, texture_coordinates }
  }

  pub fn binding_description() -> vk::VertexInputBindingDescription {
    vk::VertexInputBindingDescription::builder()
        .binding(0)
        .stride(size_of::<Vertex<f32>>() as u32)
        .input_rate(vk::VertexInputRate::VERTEX)
        .build()
  }

  pub fn attribute_descriptions()
      -> [vk::VertexInputAttributeDescription; 3]
  {
    let position = vk::VertexInputAttributeDescription::builder()
            .binding(0)
            .location(0)
            .format(vk::Format::R32G32_SFLOAT)
            .offset(0)
            .build();

    let color = vk::VertexInputAttributeDescription::builder()
            .binding(0)
            .location(1)
            .format(vk::Format::R32G32B32_SFLOAT)
            .offset(size_of::<Vec2<f32>>() as u32)
            .build();

    let texture_coordinates = vk::VertexInputAttributeDescription::builder()
            .binding(0)
            .location(2)
            .format(vk::Format::R32G32_SFLOAT)
            .offset((size_of::<Vec2<f32>>() + size_of::<Vec3<f32>>()) as u32)
            .build();

    [position, color, texture_coordinates]
  }
}