use bevy::{log::LogPlugin, prelude::*};
use bevy_ecs_markers::{
    params::{Marker, MarkerMut},
    EntityMarker, MarkerExt,
};

#[derive(EntityMarker)]
struct CurrentPlayer;

#[derive(Component)]
struct Player {
    name: &'static str,
}

fn main() {
    App::new()
        .add_plugins(LogPlugin::default())
        .init_marker::<CurrentPlayer>()
        .add_systems(Startup, (setup, name_current_player).chain())
        .run();
}

fn setup(mut commands: Commands, mut current: MarkerMut<CurrentPlayer>) {
    let _ = commands.spawn(Player { name: "Gabriel" }).id();

    let liam = commands.spawn(Player { name: "Liam" }).id();
    current.assign(liam);
}

fn name_current_player(query: Query<&Player>, current: Marker<CurrentPlayer>) {
    let Ok(player) = query.get(current.id()) else {
        warn!("Current Player not set yet!");
        return;
    };

    info!("The player is called {}", player.name);
}