game state and restart, but at what cost?? (my mental health)

src/core/game_state.rs

@@ -0,0 +1,87 @@
+use bevy::{ecs::system::SystemParam, prelude::*};
+
+use crate::core::{kirby::Kirby, wave::BubbleWaves};
+
+#[derive(Event)]
+struct EndGameEvent {
+    pub reason: EndGameReason,
+}
+
+#[derive(Clone, Copy, Debug)]
+enum EndGameReason {
+    Die,
+    Victory,
+}
+
+fn no_kirbies_emetter(mut commands: Commands, query: Query<(), With<Kirby>>) {
+    if query.is_empty() {
+        commands.trigger(EndGameEvent { reason: EndGameReason::Die });
+    };
+}
+
+#[derive(States, Default, Debug, Clone, PartialEq, Eq, Hash)]
+pub enum GameState {
+    #[default]
+    Starting,
+    Running,
+    Paused,
+}
+
+#[derive(SystemSet, Debug, Hash, PartialEq, Eq, Clone)]
+pub struct GameStartupSet;
+
+#[derive(Component, Default)]
+pub struct DispawnOnGameOver;
+
+pub trait Resetable {
+    fn reset(&mut self);
+}
+
+fn reset_resource<T: Resource + Resetable>(mut res: ResMut<T>) {
+    res.reset();
+}
+
+#[derive(SystemParam)]
+struct GameRes<'w> {
+    bubble_waves: ResMut<'w, BubbleWaves>,
+}
+
+fn on_reset_world(
+    _: On<ResetWorldEvent>,
+    mut commands: Commands,
+    entities: Query<Entity, With<DispawnOnGameOver>>,
+    game_res: GameRes,
+) {
+    for e in &entities {
+        commands.entity(e).despawn();
+    }
+    reset_resource(game_res.bubble_waves);
+    println!("Set state");
+    commands.set_state(GameState::Starting);
+}
+
+#[derive(Event)]
+struct ResetWorldEvent;
+
+fn on_end_game(event: On<EndGameEvent>, mut commands: Commands) {
+    let reason = event.reason;
+    println!("end game reason {:?}", reason);
+    commands.trigger(ResetWorldEvent);
+}
+
+fn change_to_running_state(mut commands: Commands) {
+    println!("Running state !");
+    commands.set_state(GameState::Running);
+}
+
+pub struct GameEventsPlugin;
+
+impl Plugin for GameEventsPlugin {
+    fn build(&self, app: &mut App) {
+        app.init_state::<GameState>()
+            .add_systems(Update, no_kirbies_emetter.run_if(in_state(GameState::Running)))
+            .add_systems(OnEnter(GameState::Starting), change_to_running_state.after(GameStartupSet))
+            .add_observer(on_end_game)
+            .add_observer(on_reset_world);
+    }
+}