Synchronize enchanting table pickup animation

Author: Arbousier1

common/src/main/java/com/loohp/interactionvisualizer/objectholders/EnchantmentTableAnimation.java

@@ -67,6 +67,9 @@ public class EnchantmentTableAnimation {
     public static final int PLAY_PICKUP = 2;
     public static final int CLOSE_TABLE = 3;
 
+    // ClientboundTakeItemEntityPacket uses a fixed three-tick client animation.
+    private static final int CLIENT_PICKUP_ANIMATION_TICKS = 3;
+
     private static final Map<Block, EnchantmentTableAnimation> tables = new ConcurrentHashMap<>();
 
     public static EnchantmentTableAnimation getTableAnimation(Block block, Player player) {
@@ -88,6 +91,8 @@ public static EnchantmentTableAnimation getTableAnimation(Block block, Player pl
     private final Queue<Supplier<CompletableFuture<Integer>>> taskQueue;
     private final AtomicBoolean enchanting;
     private Optional<Item> item;
+    // Inventory transfer can finish while the scheduled enchant visual is still playing.
+    private volatile PendingPickup pendingPickup;
 
     private EnchantmentTableAnimation(Block block, Player enchanter) {
         this.plugin = InteractionVisualizer.plugin;
@@ -223,13 +228,41 @@ private CompletableFuture<Integer> playEnchantAnimation(Map<Enchantment, Integer
             item.setGravity(false);
             DisplayManager.updateItem(item);
             item.setLocked(false);
-            future.complete(PLAY_ENCHANTMENT);
 
-            this.enchanting.set(false);
+            if (!playPendingPickup(future)) {
+                this.enchanting.set(false);
+                future.complete(PLAY_ENCHANTMENT);
+            }
         }, 98);
         return future;
     }
 
+    private boolean playPendingPickup(CompletableFuture<Integer> enchantFuture) {
+        PendingPickup pending = pendingPickup;
+        pendingPickup = null;
+        if (pending == null) {
+            return false;
+        }
+
+        try {
+            if (!pending.condition().test(this)) {
+                return false;
+            }
+            playPickUpAnimation(pending.itemStack()).whenComplete((ignored, throwable) -> {
+                this.enchanting.set(false);
+                if (throwable == null) {
+                    enchantFuture.complete(PLAY_ENCHANTMENT);
+                } else {
+                    enchantFuture.completeExceptionally(throwable);
+                }
+            });
+        } catch (Throwable throwable) {
+            this.enchanting.set(false);
+            enchantFuture.completeExceptionally(throwable);
+        }
+        return true;
+    }
+
     private CompletableFuture<Integer> playPickUpAnimation(ItemStack itemstack) {
         CompletableFuture<Integer> future = new CompletableFuture<>();
 
@@ -238,8 +271,8 @@ private CompletableFuture<Integer> playPickUpAnimation(ItemStack itemstack) {
             return future;
         }
         Item item = this.item.get();
-        item.setLocked(true);
         item.setItemStack(itemstack);
+        item.setLocked(true);
         if (itemstack == null || itemstack.getType().equals(Material.AIR)) {
             future.complete(PLAY_PICKUP);
             return future;
@@ -251,7 +284,7 @@ private CompletableFuture<Integer> playPickUpAnimation(ItemStack itemstack) {
         Scheduler.runTaskLater(plugin, () -> {
             this.item = Optional.empty();
             future.complete(PLAY_PICKUP);
-        }, 8);
+        }, CLIENT_PICKUP_ANIMATION_TICKS);
         return future;
     }
 
@@ -332,9 +365,14 @@ public void queueEnchant(Map<Enchantment, Integer> enchantsToAdd, int expCost, I
     }
 
     public void queuePickupAnimation(ItemStack itemstack, Predicate<EnchantmentTableAnimation> condition) {
+        ItemStack copy = itemstack == null ? null : itemstack.clone();
+        if (enchanting.get() && copy != null && !copy.isEmpty()) {
+            pendingPickup = new PendingPickup(copy, condition);
+            return;
+        }
         taskQueue.add(() -> {
             if (condition.test(this)) {
-                return playPickUpAnimation(itemstack == null ? null : itemstack.clone());
+                return playPickUpAnimation(copy);
             } else {
                 return null;
             }
@@ -351,4 +389,7 @@ public void queueClose(Predicate<EnchantmentTableAnimation> condition) {
         });
     }
 
+    private record PendingPickup(ItemStack itemStack, Predicate<EnchantmentTableAnimation> condition) {
+    }
+
 }