From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Owen1212055 <23108066+Owen1212055@users.noreply.github.com>
Date: Wed, 7 Dec 2022 17:25:19 -0500
Subject: [PATCH] Properly resend entities

This resolves some issues which caused entities to not be resent correctly.
Entities that are interacted with need to be resent to the client, so we resend all the entity
data to the player whilst making sure not to clear dirty entries from the tracker. This makes
sure that values will be correctly updated to other players.

This also adds utilities to aid in further preventing entity desyncs.

See: https://github.com/PaperMC/Paper/pull/1896

== AT ==
public net.minecraft.server.level.ChunkMap$TrackedEntity serverEntity

diff --git a/src/main/java/net/minecraft/network/syncher/SynchedEntityData.java b/src/main/java/net/minecraft/network/syncher/SynchedEntityData.java
index d088479d160dbd2fc90b48a30553be141db8eef2..15add3f4dfd718ec09bb1db4f22223466936879c 100644
--- a/src/main/java/net/minecraft/network/syncher/SynchedEntityData.java
+++ b/src/main/java/net/minecraft/network/syncher/SynchedEntityData.java
@@ -253,14 +253,60 @@ public class SynchedEntityData {
     // CraftBukkit start
     public void refresh(ServerPlayer to) {
         if (!this.isEmpty()) {
-            List<SynchedEntityData.DataValue<?>> list = this.getNonDefaultValues();
+            List<SynchedEntityData.DataValue<?>> list = this.packAll(); // Paper - Update EVERYTHING not just not default
 
             if (list != null) {
+                if (to.getBukkitEntity().canSee(this.entity.getBukkitEntity())) { // Paper
                 to.connection.send(new ClientboundSetEntityDataPacket(this.entity.getId(), list));
+                } // Paper
             }
         }
     }
     // CraftBukkit end
+    // Paper start
+    // We need to pack all as we cannot rely on "non default values" or "dirty" ones.
+    // Because these values can possibly be desynced on the client.
+    @Nullable
+    private List<SynchedEntityData.DataValue<?>> packAll() {
+        if (this.isEmpty()) {
+            return null;
+        }
+
+        List<SynchedEntityData.DataValue<?>> list = new ArrayList<>();
+        for (DataItem<?> dataItem : this.itemsById.values()) {
+            list.add(dataItem.value());
+        }
+
+        return list;
+    }
+
+    // This method should only be used if the data of an entity could have became desynced
+    // due to interactions on the client.
+    public void resendPossiblyDesyncedEntity(ServerPlayer player) {
+        if (this.entity.tracker == null) {
+            return;
+        }
+
+        net.minecraft.server.level.ServerEntity serverEntity = this.entity.tracker.serverEntity;
+        if (player.getBukkitEntity().canSee(entity.getBukkitEntity())) {
+            serverEntity.sendPairingData(player, player.connection::send);
+        }
+    }
+
+    // This method allows you to specifically resend certain data accessor keys to the client
+    public void resendPossiblyDesyncedDataValues(List<EntityDataAccessor<?>> keys, ServerPlayer to) {
+        if (!to.getBukkitEntity().canSee(this.entity.getBukkitEntity())) {
+            return;
+        }
+        List<SynchedEntityData.DataValue<?>> values = new ArrayList<>(keys.size());
+        for (EntityDataAccessor<?> key : keys) {
+            SynchedEntityData.DataItem<?> synchedValue = this.getItem(key);
+            values.add(synchedValue.value());
+        }
+
+        to.connection.send(new ClientboundSetEntityDataPacket(this.entity.getId(), values));
+    }
+    // Paper end
 
     public static class DataItem<T> {
 
diff --git a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
index db5368bf4970c63f21ef1e5fc7428787c90de4dd..9372f2363b13dca1b5ae77a509daaec7fbbf5e4f 100644
--- a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
+++ b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
@@ -2648,7 +2648,7 @@ public class ServerGamePacketListenerImpl extends ServerCommonPacketListenerImpl
 
                             // Entity in bucket - SPIGOT-4048 and SPIGOT-6859a
                             if ((entity instanceof Bucketable && entity instanceof LivingEntity && origItem != null && origItem.asItem() == Items.WATER_BUCKET) && (event.isCancelled() || ServerGamePacketListenerImpl.this.player.getInventory().getSelected() == null || ServerGamePacketListenerImpl.this.player.getInventory().getSelected().getItem() != origItem)) {
-                                send(new ClientboundAddEntityPacket(entity));
+                                entity.getEntityData().resendPossiblyDesyncedEntity(player); // Paper - The entire mob gets deleted, so resend it.
                                 player.containerMenu.sendAllDataToRemote();
                             }
 
diff --git a/src/main/java/net/minecraft/server/players/PlayerList.java b/src/main/java/net/minecraft/server/players/PlayerList.java
index 255f7ab2560e493770bd99a8404f3c122cfca2ad..a56995333931685eecf6ea90ff1a89d38b4a2336 100644
--- a/src/main/java/net/minecraft/server/players/PlayerList.java
+++ b/src/main/java/net/minecraft/server/players/PlayerList.java
@@ -357,7 +357,7 @@ public abstract class PlayerList {
         ((ServerLevel)player.level()).getChunkSource().chunkMap.addEntity(player); // Paper - track entity now
         // CraftBukkit end
 
-        player.getEntityData().refresh(player); // CraftBukkit - BungeeCord#2321, send complete data to self on spawn
+        //player.getEntityData().refresh(player); // CraftBukkit - BungeeCord#2321, send complete data to self on spawn Paper - THIS IS NOT NEEDED ANYMORE
 
         this.sendLevelInfo(player, worldserver1);
 
diff --git a/src/main/java/net/minecraft/world/entity/animal/Bucketable.java b/src/main/java/net/minecraft/world/entity/animal/Bucketable.java
index 37596c7b65f280be00e8e59ae18bd1aceae21080..eca18540aeb0b0d4098477d73b14c78a7bf9f455 100644
--- a/src/main/java/net/minecraft/world/entity/animal/Bucketable.java
+++ b/src/main/java/net/minecraft/world/entity/animal/Bucketable.java
@@ -109,8 +109,7 @@ public interface Bucketable {
             itemstack1 = CraftItemStack.asNMSCopy(playerBucketFishEvent.getEntityBucket());
             if (playerBucketFishEvent.isCancelled()) {
                 ((ServerPlayer) player).containerMenu.sendAllDataToRemote(); // We need to update inventory to resync client's bucket
-                ((ServerPlayer) player).connection.send(new ClientboundAddEntityPacket(entity)); // We need to play out these packets as the client assumes the fish is gone
-                entity.getEntityData().refresh((ServerPlayer) player); // Need to send data such as the display name to client
+                entity.getEntityData().resendPossiblyDesyncedEntity((ServerPlayer) player); // Paper
                 return Optional.of(InteractionResult.FAIL);
             }
             entity.playSound(((Bucketable) entity).getPickupSound(), 1.0F, 1.0F);