Stephan/hez 2 npc should loose head if 0 health (#34)

src/backpack/backpack_ui.rs

@@ -181,7 +181,7 @@ fn spawn_head_ui(
                                 top: Val::Px(0.),
                                 left: Val::Px(0.),
                                 right: Val::Px(0.),
-                                height: Val::Percent(25.),
+                                height: Val::Percent(0.),
                                 ..default()
                             },
                         ))

src/backpack/mod.rs

@@ -2,8 +2,7 @@ mod backpack_ui;
 mod ui_head_state;
 
 use crate::{
-    GameState,
-    heads::{HEAD_COUNT, HeadState},
+    cash::CashCollectEvent, global_observer, head_drop::HeadCollected, heads::HeadState,
     heads_database::HeadsDatabase,
 };
 use bevy::prelude::*;
@@ -26,21 +25,38 @@ impl Backpack {
 
         false
     }
+
+    pub fn contains(&self, head_id: usize) -> bool {
+        self.heads.iter().any(|head| head.head == head_id)
+    }
+
+    pub fn insert(&mut self, head_id: usize, heads_db: &HeadsDatabase) {
+        self.heads.push(HeadState::new(head_id, heads_db));
+    }
 }
 
 #[derive(Event)]
 pub struct BackbackSwapEvent(pub usize);
 
 pub fn plugin(app: &mut App) {
+    app.init_resource::<Backpack>();
+
     app.add_plugins(backpack_ui::plugin);
 
-    app.add_systems(OnEnter(GameState::Playing), setup);
+    global_observer!(app, on_head_collect);
 }
 
-fn setup(mut commands: Commands, heads: Res<HeadsDatabase>) {
-    commands.insert_resource(Backpack {
-        heads: (0usize..HEAD_COUNT)
-            .map(|i| HeadState::new(i, heads.as_ref()))
-            .collect(),
-    });
+fn on_head_collect(
+    trigger: Trigger<HeadCollected>,
+    mut cmds: Commands,
+    mut backpack: ResMut<Backpack>,
+    heads_db: Res<HeadsDatabase>,
+) {
+    let HeadCollected(head) = *trigger.event();
+
+    if backpack.contains(head) {
+        cmds.trigger(CashCollectEvent);
+    } else {
+        backpack.insert(head, heads_db.as_ref());
+    }
 }