use crate::grid;
use bevy::{
    prelude::*,
    reflect::TypeUuid,
    render::render_resource::{AsBindGroup, ShaderRef},
    sprite::{Material2d, Material2dPlugin, MaterialMesh2dBundle},
};

pub struct CanvasPlugin;

impl Plugin for CanvasPlugin {
    fn build(&self, app: &mut App) {
        app.add_plugin(Material2dPlugin::<CanvasMaterial>::default())
            .add_startup_system(spawn_canvas);
    }
}

#[derive(AsBindGroup, TypeUuid, Clone)]
#[uuid = "24f83f6e-e52d-41a6-bf1d-0e46e57a4995"]
struct CanvasMaterial {}

impl Material2d for CanvasMaterial {
    fn fragment_shader() -> ShaderRef {
        "canvas_shader.wgsl".into()
    }
}

fn spawn_canvas(
    mut commands: Commands,
    mut mesh_assets: ResMut<Assets<Mesh>>,
    mut canvas_material_assets: ResMut<Assets<CanvasMaterial>>,
) {
    commands
        .spawn(MaterialMesh2dBundle {
            mesh: mesh_assets.add(Mesh::from(shape::Quad::default())).into(),
            material: canvas_material_assets.add(CanvasMaterial {}),
            transform: Transform::from_scale(Vec3::splat(
                grid::SEGMENT_SIZE * f32::from(grid::SIZE),
            )),
            ..Default::default()
        })
        .insert(Name::new("Canvas"));
}