feat: Implement Game Over state and UI cleanup

README.md

@@ -43,10 +43,10 @@ nix develop --command bash -c "cargo build"
     *   ~~Add a `PlayerLives` resource (e.g., starting with 3).~~
     *   ~~Modify `check_player_enemy_collisions`: Instead of just printing, decrement the lives count.~~
     *   ~~Implement player destruction (despawn the player sprite) and respawn logic (maybe after a short delay, with temporary invincibility).~~
-*   **Game Over State:**
-    *   Use Bevy's `States` (e.g., `Playing`, `GameOver`).
-    *   Transition to `GameOver` when `PlayerLives` reaches zero.
-    *   In the `GameOver` state: stop enemy spawning, stop player controls, display a "Game Over" message (using `bevy_ui`), potentially offer a restart option.
+*   ~~**Game Over State:**~~ **(DONE)**
+    *   ~~Use Bevy's `States` (e.g., `Playing`, `GameOver`).~~
+    *   ~~Transition to `GameOver` when `PlayerLives` reaches zero.~~
+    *   ~~In the `GameOver` state: stop enemy spawning, stop player controls, display a "Game Over" message (using `bevy_ui`), potentially offer a restart option.~~
 *   **Scoring:**
     *   Add a `Score` resource.
     *   Increment the score in `check_bullet_collisions` when an enemy is hit.

src/main.rs

@@ -1,6 +1,12 @@
-use bevy::prelude::*;
+use bevy::prelude::*; // Removed unused AppExit
 use std::time::Duration;
-
+// --- Game States ---
+#[derive(Clone, Eq, PartialEq, Debug, Hash, Default, States)]
+enum AppState {
+    #[default]
+    Playing,
+    GameOver,
+}
 // --- Constants ---
 const WINDOW_WIDTH: f32 = 600.0;
 const WINDOW_HEIGHT: f32 = 800.0;
@@ -53,9 +59,65 @@ struct PlayerRespawnTimer {
     timer: Timer,
 }
 
+// --- Game Over UI ---
+
+#[derive(Component)]
+struct GameOverUI;
+
+fn setup_game_over_ui(mut commands: Commands) {
+   println!("Entering GameOver state. Setting up UI.");
+   commands.spawn((
+       TextBundle::from_section(
+           "GAME OVER",
+           TextStyle {
+               font_size: 100.0,
+               color: Color::WHITE,
+               ..default()
+           },
+       )
+       .with_style(Style {
+           position_type: PositionType::Absolute,
+           align_self: AlignSelf::Center,
+           justify_self: JustifySelf::Center,
+           top: Val::Percent(40.0), // Center vertically roughly
+           ..default()
+       }),
+       GameOverUI, // Tag the UI element
+   ));
+   // TODO: Add "Press R to Restart" text later
+}
+
+fn cleanup_game_over_ui(mut commands: Commands, query: Query<Entity, With<GameOverUI>>) {
+    println!("Exiting GameOver state. Cleaning up UI.");
+   for entity in query.iter() {
+       commands.entity(entity).despawn_recursive();
+   }
+}
+
+// --- Cleanup ---
+
+fn cleanup_game_entities(
+   mut commands: Commands,
+   bullet_query: Query<Entity, With<Bullet>>,
+   enemy_query: Query<Entity, With<Enemy>>,
+   // Optionally despawn player too, or handle separately if needed for restart
+   // player_query: Query<Entity, With<Player>>,
+) {
+   println!("Exiting Playing state. Cleaning up game entities.");
+   for entity in bullet_query.iter() {
+       commands.entity(entity).despawn();
+   }
+   for entity in enemy_query.iter() {
+       commands.entity(entity).despawn();
+   }
+   // for entity in player_query.iter() {
+   //     commands.entity(entity).despawn();
+   // }
+}
 
 fn main() {
-    App::new()
+    App::new() // Start App builder
+        .init_state::<AppState>() // Initialize the AppState *after* App::new()
         .insert_resource(ClearColor(Color::rgb(0.0, 0.0, 0.0)))
         .add_plugins(DefaultPlugins.set(WindowPlugin {
             primary_window: Some(Window {
@@ -76,19 +138,29 @@ fn main() {
         })
         // Add Systems
         .add_systems(Startup, setup)
+        // Systems running only when Playing
         .add_systems(Update, (
             move_player,
-            player_shoot.run_if(player_exists), // Only shoot if player exists
+            player_shoot.run_if(player_exists),
             move_bullets,
             move_enemies,
             spawn_enemies,
             check_bullet_collisions,
-            check_player_enemy_collisions.run_if(player_vulnerable), // Only check if player exists and is not invincible
-            respawn_player.run_if(should_respawn_player), // Conditionally run respawn
-            manage_invincibility, // Handle invincibility timer and blinking
-            update_window_title, // Show lives in window title
-            // (Game Over check would go here later)
+            check_player_enemy_collisions.run_if(player_vulnerable),
+            respawn_player.run_if(should_respawn_player),
+            manage_invincibility,
+            // Game Over check is now implicit in check_player_enemy_collisions
+        ).run_if(in_state(AppState::Playing)))
+        // Systems running regardless of state (or managing state transitions)
+        .add_systems(Update, (
+            update_window_title, // Keep title updated
+            // Add system to check for restart input in GameOver state later
+            bevy::window::close_on_esc, // Allow closing anytime
         ))
+        // Systems for entering/exiting states
+        .add_systems(OnEnter(AppState::GameOver), setup_game_over_ui)
+        .add_systems(OnExit(AppState::GameOver), cleanup_game_over_ui)
+        .add_systems(OnExit(AppState::Playing), cleanup_game_entities) // Cleanup when leaving Playing
         .run();
 }
 
@@ -275,6 +347,7 @@ fn check_player_enemy_collisions(
     mut commands: Commands,
     mut lives: ResMut<PlayerLives>,
     mut respawn_timer: ResMut<PlayerRespawnTimer>,
+    mut next_state: ResMut<NextState<AppState>>, // Resource to change state
     // Query player without Invincible component - relies on run_if condition too
     player_query: Query<(Entity, &Transform), (With<Player>, Without<Invincible>)>, 
     enemy_query: Query<(Entity, &Transform), With<Enemy>>,
@@ -300,7 +373,7 @@ fn check_player_enemy_collisions(
                     println!("Respawn timer started.");
                 } else {
                     println!("GAME OVER!");
-                    // Game Over logic would go here - e.g., transition to a GameOver state
+                    next_state.set(AppState::GameOver); // Transition to GameOver state
                 }
                 // Important: Break after handling one collision per frame for the player
                 break;