From e88cea8402eb1ab94249c10e298c43875ac8b17f Mon Sep 17 00:00:00 2001
From: Wesley Wolfe <weswolf@aol.com>
Date: Tue, 23 Jul 2013 21:39:30 -0500
Subject: [PATCH] Check interactable items before event. Fixes BUKKIT-4576

Items that cause entities to change state, including tags, chest, and
leashes, do not update the client properly following the firing of
PlayerInteractEntityEvent. This change makes the item checks occur
before the event fires, to concur with the client's assumptions.
---
 .../minecraft/server/PlayerConnection.java    | 26 ++++++++++++-------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/src/main/java/net/minecraft/server/PlayerConnection.java b/src/main/java/net/minecraft/server/PlayerConnection.java
index ff685d5942..6aa7a21b2a 100644
--- a/src/main/java/net/minecraft/server/PlayerConnection.java
+++ b/src/main/java/net/minecraft/server/PlayerConnection.java
@@ -24,7 +24,6 @@ import org.bukkit.craftbukkit.util.Waitable;
 import org.bukkit.craftbukkit.entity.CraftPlayer;
 import org.bukkit.craftbukkit.event.CraftEventFactory;
 
-import org.bukkit.Bukkit;
 import org.bukkit.Location;
 import org.bukkit.entity.Player;
 import org.bukkit.event.Event;
@@ -35,7 +34,6 @@ import org.bukkit.event.inventory.CraftItemEvent;
 import org.bukkit.event.inventory.InventoryAction;
 import org.bukkit.event.inventory.InventoryClickEvent;
 import org.bukkit.event.inventory.InventoryCreativeEvent;
-import org.bukkit.event.inventory.InventoryCloseEvent;
 import org.bukkit.event.inventory.InventoryType.SlotType;
 import org.bukkit.event.player.AsyncPlayerChatEvent;
 import org.bukkit.event.player.PlayerAnimationEvent;
@@ -1083,18 +1081,26 @@ public class PlayerConnection extends Connection {
                 ItemStack itemInHand = this.player.inventory.getItemInHand(); // CraftBukkit
                 if (packet7useentity.action == 0) {
                     // CraftBukkit start
+                    boolean triggerTagUpdate = itemInHand != null && itemInHand.id == Item.NAME_TAG.id && entity instanceof EntityInsentient;
+                    boolean triggerChestUpdate = itemInHand != null && itemInHand.id == Block.CHEST.id && entity instanceof EntityHorse;
+                    boolean triggerLeashUpdate = itemInHand != null && itemInHand.id == Item.LEASH.id && entity instanceof EntityInsentient;
                     PlayerInteractEntityEvent event = new PlayerInteractEntityEvent((Player) this.getPlayer(), entity.getBukkitEntity());
                     this.server.getPluginManager().callEvent(event);
 
+                    if (triggerLeashUpdate && (event.isCancelled() || this.player.inventory.getItemInHand() == null || this.player.inventory.getItemInHand().id != Item.LEASH.id)) {
+                        // Refresh the current leash state
+                        this.sendPacket(new Packet39AttachEntity(1, entity, ((EntityInsentient) entity).bI()));
+                    }
+
+                    if (triggerTagUpdate && (event.isCancelled() || this.player.inventory.getItemInHand() == null || this.player.inventory.getItemInHand().id != Item.NAME_TAG.id)) {
+                        // Refresh the current entity metadata
+                        this.sendPacket(new Packet40EntityMetadata(entity.id, entity.datawatcher, true));
+                    }
+                    if (triggerChestUpdate && (event.isCancelled() || this.player.inventory.getItemInHand() == null || this.player.inventory.getItemInHand().id != Block.CHEST.id)) {
+                        this.sendPacket(new Packet40EntityMetadata(entity.id, entity.datawatcher, true));
+                    }
+
                     if (event.isCancelled()) {
-                        if (itemInHand != null && itemInHand.id == Item.LEASH.id && entity instanceof EntityInsentient) {
-                            // Refresh the current leash state
-                            this.sendPacket(new Packet39AttachEntity(1, entity, ((EntityInsentient) entity).bI()));
-                        }
-                        if (itemInHand != null && itemInHand.id == Item.NAME_TAG.id && entity instanceof EntityInsentient) {
-                            // Refresh the current entity metadata
-                            this.sendPacket(new Packet40EntityMetadata(entity.id, entity.datawatcher, true));
-                        }
                         return;
                     }
                     // CraftBukkit end