player can take damage

src/heads/mod.rs

@@ -4,7 +4,8 @@ use crate::{
     GameState,
     abilities::HeadAbility,
     backpack::{BackbackSwapEvent, Backpack},
-    player::head_id_to_str,
+    hitpoints::Hitpoints,
+    player::{Player, head_id_to_str},
     sounds::PlaySound,
 };
 use bevy::prelude::*;
@@ -92,6 +93,15 @@ impl ActiveHeads {
 
         false
     }
+
+    pub fn set_hitpoint(&mut self, hp: &Hitpoints) {
+        let Some(head) = &mut self.heads[self.current_slot] else {
+            error!("cannot use ammo of empty head");
+            return;
+        };
+
+        (head.health, head.health_max) = hp.get()
+    }
 }
 
 #[derive(Event, Reflect)]
@@ -118,7 +128,10 @@ pub fn plugin(app: &mut App) {
     });
 
     app.add_systems(OnEnter(GameState::Playing), setup);
-    app.add_systems(Update, reload.run_if(in_state(GameState::Playing)));
+    app.add_systems(
+        Update,
+        (reload, sync_hp).run_if(in_state(GameState::Playing)),
+    );
 
     app.add_observer(on_select_active_head);
     app.add_observer(on_swap_backpack);
@@ -133,6 +146,14 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
     commands.insert_resource(HeadsImages { heads });
 }
 
+fn sync_hp(mut active: ResMut<ActiveHeads>, query: Query<&Hitpoints, With<Player>>) {
+    let Ok(hp) = query.get_single() else {
+        return;
+    };
+
+    active.set_hitpoint(hp);
+}
+
 fn reload(mut commands: Commands, mut active: ResMut<ActiveHeads>, time: Res<Time>) {
     if !active.reloading() {
         return;
@@ -154,6 +175,7 @@ fn on_select_active_head(
     trigger: Trigger<SelectActiveHead>,
     mut commands: Commands,
     mut res: ResMut<ActiveHeads>,
+    mut query: Query<&mut Hitpoints, With<Player>>,
 ) {
     match trigger.event() {
         SelectActiveHead::Right => {
@@ -164,6 +186,12 @@ fn on_select_active_head(
         }
     }
 
+    // sync health back into Hitpoints
+    let Ok(mut hp) = query.get_single_mut() else {
+        return;
+    };
+    hp.set_health(res.current().unwrap().health);
+
     commands.trigger(PlaySound::Selection);
     commands.trigger(HeadChanged(res.heads[res.current_slot].unwrap().head));
 }
@@ -173,6 +201,7 @@ fn on_swap_backpack(
     mut commands: Commands,
     mut res: ResMut<ActiveHeads>,
     mut backpack: ResMut<Backpack>,
+    mut query: Query<&mut Hitpoints, With<Player>>,
 ) {
     let backpack_slot = trigger.event().0;
 
@@ -189,5 +218,11 @@ fn on_swap_backpack(
         backpack.heads.remove(backpack_slot);
     }
 
+    // sync health back into Hitpoints
+    let Ok(mut hp) = query.get_single_mut() else {
+        return;
+    };
+    hp.set_health(res.current().unwrap().health);
+
     commands.trigger(HeadChanged(res.heads[res.current_slot].unwrap().head));
 }