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

use crate::MainCamera;

#[derive(AsBindGroup, TypeUuid, Debug, Clone)]
#[uuid = "b56a4075-b836-4866-a6f6-3e34ef3ae44f"]
pub struct GridMaterial {
    #[uniform(0)]
    width: f32,
    #[uniform(1)]
    size: Vec2,
    #[uniform(2)]
    visible: u32,
}

impl Material2d for GridMaterial {
    fn fragment_shader() -> bevy::render::render_resource::ShaderRef {
        "shaders/grid.wgsl".into()
    }
}

pub fn spawn_grid(
    mut coms: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut mats: ResMut<Assets<GridMaterial>>,
) {

    coms.spawn().insert_bundle(MaterialMesh2dBundle {
        mesh: meshes.add(Mesh::from(shape::Cube { size: 1000.0 })).into(),
        transform: Transform::from_xyz(0.0, 0.0, 0.0),
        material: mats.add(GridMaterial { width: 2.0, size: Vec2::splat(15.0), visible: 1 }),
        ..default()
    });
}

pub fn update_grid_shader(
    snap_grid: Res<crate::SnapGrid>,
    handles: Query<&Handle<GridMaterial>>,
    mut mats: ResMut<Assets<GridMaterial>>,
) {
    for h in handles.iter() {
        if let Some(mut m) = mats.get_mut(h) {
            m.size = Vec2::new(snap_grid.width, snap_grid.height);
            m.visible = snap_grid.visible as u32;
        }
    }
}

pub fn update_grid_position(
    cam: Query<&GlobalTransform, With<MainCamera>>,
    mut grid: Query<&mut Transform, With<Handle<GridMaterial>>>, 
) {
    let mut cam_pos = cam.get_single().map(|c| c.translation()).unwrap_or(Vec3::ZERO);
    cam_pos.z = 0.0;
    for mut t in grid.iter_mut() {
        t.translation = cam_pos;
    }
}