fix: clear a plate's sauce once its last food is taken off

src/main/java/net/tfminecraft/cooking/manager/PlateManager.java

@@ -10,6 +10,7 @@
 import org.bukkit.Sound;
 import org.bukkit.entity.Player;
 import org.bukkit.event.EventHandler;
+import org.bukkit.event.EventPriority;
 import org.bukkit.event.Listener;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.inventory.meta.ItemMeta;
@@ -31,6 +32,7 @@
 import net.tfminecraft.interactiblefurniture.events.FurnitureBreakEvent;
 import net.tfminecraft.interactiblefurniture.events.FurnitureInteractEvent;
 import net.tfminecraft.interactiblefurniture.events.FurnitureSlotItemAddEvent;
+import net.tfminecraft.interactiblefurniture.events.FurnitureSlotItemTakeEvent;
 import net.tfminecraft.interactiblefurniture.furniture.Furniture;
 import net.tfminecraft.interactiblefurniture.furniture.PlacedSlot;
 import net.tfminecraft.interactiblefurniture.furniture.data.DisplayData;
@@ -56,6 +58,11 @@ public void run() {
     }
 
     public void update(Furniture f) {
+        // Also clears plates saved with leftover sauce before the take handler existed.
+        if(hasLeftoverSauce(f, null)) {
+            f.removeActiveSlot("sauce");
+            InteractibleFurniture.getInstance().getFurnitureManager().persistFurniture(f);
+        }
         for(PlacedSlot slot : f.getActiveSlots().values()) {
             if(slot.getId().contains("display")) continue;
             ItemStack item = slot.getCurrentItem();
@@ -99,10 +106,51 @@ public boolean hasSauce(Furniture f) {
         return false;
     }
 
+    /**
+     * True when the plate shows a sauce visual but no food would remain once {@code leavingSlot}
+     * is gone. A leftover sauce visual makes hasSauce reject the next dish on the plate.
+     */
+    boolean hasLeftoverSauce(Furniture f, String leavingSlot) {
+        if(!f.hasActiveSlot("sauce")) return false;
+        return !hasFood(f, leavingSlot);
+    }
+
+    // An active food slot counts even without a loaded item: restore can leave the item unset
+    // while the display still shows the food.
+    private boolean hasFood(Furniture f, String ignoredSlot) {
+        for(String id : f.getActiveSlots().keySet()) {
+            if(id.equals("sauce") || id.contains("display") || id.equals(ignoredSlot)) continue;
+            return true;
+        }
+        return false;
+    }
+
+    // Food addSauce can actually apply the sauce to.
+    private boolean hasSauceableFood(Furniture f) {
+        for(PlacedSlot slot : f.getActiveSlots().values()) {
+            if(slot.getId().equals("sauce") || slot.getId().contains("display")) continue;
+            ItemStack item = slot.getCurrentItem();
+            if(item != null && FoodItem.fromItem(item) != null) return true;
+        }
+        return false;
+    }
+
+    @EventHandler(priority = EventPriority.HIGHEST, ignoreCancelled = true)
+    public void takeItem(FurnitureSlotItemTakeEvent e) {
+        Furniture f = e.getFurniture();
+        if(!FurnitureCache.isPlate(f)) return;
+        // The taken slot is still active here; InteractibleFurniture removes it and saves the plate next.
+        if(hasLeftoverSauce(f, e.getSlot().getId())) {
+            f.removeActiveSlot("sauce");
+        }
+    }
+
     // Keep the existing legacy text representation, formatting, and exact-string comparisons.
     @SuppressWarnings("deprecation")
     public void addSauce(Player p, Furniture f, FoodItem sauce, ItemStack base) {
         if (hasSauce(f)) return;
+        // Sauce with no food to take it would never reach food added later, so keep the ladle full.
+        if (!hasSauceableFood(f)) return;
 
         // Replace player ladle with empty ladle
         p.getInventory().setItemInMainHand(

src/test/java/net/tfminecraft/cooking/manager/PlateManagerTest.java

@@ -116,4 +116,79 @@ public boolean hasItemMeta() {
 
         assertFalse(new PlateManager().hasSauce(plate));
     }
+
+    @Test
+    void sauceIsLeftoverOnceTheLastFoodLeaves() {
+        Furniture plate = plateWithSauceVisual();
+        plate.getActiveSlots().put("item_1", new PlacedSlot(plate, "item_1"));
+
+        assertFalse(new PlateManager().hasLeftoverSauce(plate, null));
+        assertTrue(new PlateManager().hasLeftoverSauce(plate, "item_1"));
+    }
+
+    @Test
+    void sauceStaysWhileOtherFoodRemains() {
+        Furniture plate = plateWithSauceVisual();
+        plate.getActiveSlots().put("item_1", new PlacedSlot(plate, "item_1"));
+        plate.getActiveSlots().put("item_2", new PlacedSlot(plate, "item_2"));
+
+        assertFalse(new PlateManager().hasLeftoverSauce(plate, "item_1"));
+    }
+
+    @Test
+    void sauceAloneOnAPlateIsLeftover() {
+        assertTrue(new PlateManager().hasLeftoverSauce(plateWithSauceVisual(), null));
+    }
+
+    @Test
+    void plateWithoutSauceHasNoLeftover() {
+        Furniture plate = new Furniture("plate", null, UUID.randomUUID());
+        plate.getActiveSlots().put("item_1", new PlacedSlot(plate, "item_1"));
+
+        assertFalse(new PlateManager().hasLeftoverSauce(plate, null));
+        assertFalse(new PlateManager().hasLeftoverSauce(plate, "item_1"));
+    }
+
+    @Test
+    void sauceOnAnEmptyPlateReturnsBeforeTouchingThePlayerOrLadle() {
+        Furniture plate = new Furniture("plate", null, UUID.randomUUID());
+
+        // Null interaction arguments ensure the empty-plate attempt exits before using them.
+        assertDoesNotThrow(() -> new PlateManager().addSauce(null, plate, null, null));
+        assertTrue(plate.getActiveSlots().isEmpty());
+    }
+
+    @Test
+    void sauceOnAPlateWithoutLoadedFoodReturnsBeforeTouchingThePlayerOrLadle() {
+        Furniture plate = new Furniture("plate", null, UUID.randomUUID());
+        plate.getActiveSlots().put("item_1", new PlacedSlot(plate, "item_1"));
+        PlacedSlot unrecognized = new PlacedSlot(plate, "item_2");
+        unrecognized.setModel(new ItemStack() {
+            @Override
+            public boolean hasItemMeta() {
+                return false;
+            }
+        });
+        plate.getActiveSlots().put("item_2", unrecognized);
+
+        assertDoesNotThrow(() -> new PlateManager().addSauce(null, plate, null, null));
+        assertFalse(plate.hasActiveSlot("sauce"));
+    }
+
+    @Test
+    void displaySlotsDoNotCountAsFood() {
+        Furniture plate = plateWithSauceVisual();
+        plate.getActiveSlots().put("display_1", new PlacedSlot(plate, "display_1"));
+
+        assertTrue(new PlateManager().hasLeftoverSauce(plate, null));
+    }
+
+    @Test
+    void sauceOnADisplayOnlyPlateReturnsBeforeTouchingThePlayerOrLadle() {
+        Furniture plate = new Furniture("plate", null, UUID.randomUUID());
+        plate.getActiveSlots().put("display_1", new PlacedSlot(plate, "display_1"));
+
+        assertDoesNotThrow(() -> new PlateManager().addSauce(null, plate, null, null));
+        assertFalse(plate.hasActiveSlot("sauce"));
+    }
 }