use bevy::prelude::*;
use avian3d::prelude::*;

use crate::util::ecs::PathTracer;

pub struct ProjectilesPlugin;

impl Plugin for ProjectilesPlugin
{
    fn build(&self, app: &mut App)
    {
        app.add_systems(Startup, setup_projectiles);

        app.add_event::<BulletFiredEvent>();
        app.add_systems(Update, on_bullet_fired_event.run_if(on_event::<BulletFiredEvent>));
    }
}

#[derive(Resource)]
pub struct BulletResources
{
    pub mesh: Mesh3d,
    pub material: MeshMaterial3d<StandardMaterial>,
    pub collider: Collider,
}

fn setup_projectiles(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    commands.insert_resource(BulletResources {
        mesh: Mesh3d(meshes.add(Sphere::new(1.0))),
        material: MeshMaterial3d(materials.add(StandardMaterial {
            base_color: Color::srgb(0.7, 0.1, 0.1),
            ..default()
        })),
        collider: Collider::sphere(1.0),
    });
}

#[derive(Event, Copy, Clone, PartialEq, Debug)]
pub struct BulletFiredEvent
{
    pub position: Vec3,
    pub direction: Dir3,
    pub speed: f32,
    pub radius: f32,
    pub density: f32,
}

#[derive(Component)]
pub struct Bullet;

fn on_bullet_fired_event(
    mut commands: Commands,
    mut events: EventReader<BulletFiredEvent>,
    bullet_resources: Res<BulletResources>,
) {
    let to_projectile = |event: &BulletFiredEvent|
    {
        let transform = Transform::IDENTITY
            .with_translation(event.position)
            .with_scale(Vec3::splat(event.radius))
            .looking_to(event.direction, Vec3::Y);

        (
            Bullet,
            bullet_resources.mesh.clone(),
            bullet_resources.material.clone(),
            bullet_resources.collider.clone(),
            transform,
            RigidBody::Dynamic,
            ColliderDensity(event.density),
            SpeculativeMargin(event.radius),
            SweptCcd::LINEAR,
            LinearVelocity(event.speed * event.direction),
            PathTracer::default(),
        )
    };

    commands.spawn_batch(events.read()
        .map(to_projectile)
        .collect::<Vec<_>>()
        );
}