craftbukkit/nms-patches/net/minecraft/world/inventory/ContainerAnvil.patch

--- a/net/minecraft/world/inventory/ContainerAnvil.java
+++ b/net/minecraft/world/inventory/ContainerAnvil.java
@@ -19,6 +19,10 @@
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
+// CraftBukkit start
+import org.bukkit.craftbukkit.inventory.CraftInventoryView;
+// CraftBukkit end
+
 public class ContainerAnvil extends ContainerAnvilAbstract {
 
     private static final Logger LOGGER = LogManager.getLogger();
@@ -34,6 +38,10 @@
     private static final int COST_REPAIR_SACRIFICE = 2;
     private static final int COST_INCOMPATIBLE_PENALTY = 1;
     private static final int COST_RENAME = 1;
+    // CraftBukkit start
+    public int maximumRepairCost = 40;
+    private CraftInventoryView bukkitEntity;
+    // CraftBukkit end
 
     public ContainerAnvil(int i, PlayerInventory playerinventory) {
         this(i, playerinventory, ContainerAccess.NULL);
@@ -106,7 +114,7 @@
         byte b1 = 0;
 
         if (itemstack.isEmpty()) {
-            this.resultSlots.setItem(0, ItemStack.EMPTY);
+            org.bukkit.craftbukkit.event.CraftEventFactory.callPrepareAnvilEvent(getBukkitView(), ItemStack.EMPTY); // CraftBukkit
             this.cost.set(0);
         } else {
             ItemStack itemstack1 = itemstack.cloneItemStack();
@@ -124,7 +132,7 @@
                 if (itemstack1.f() && itemstack1.getItem().a(itemstack, itemstack2)) {
                     k = Math.min(itemstack1.getDamage(), itemstack1.i() / 4);
                     if (k <= 0) {
-                        this.resultSlots.setItem(0, ItemStack.EMPTY);
+                        org.bukkit.craftbukkit.event.CraftEventFactory.callPrepareAnvilEvent(getBukkitView(), ItemStack.EMPTY); // CraftBukkit
                         this.cost.set(0);
                         return;
                     }
@@ -139,7 +147,7 @@
                     this.repairItemCountCost = i1;
                 } else {
                     if (!flag && (!itemstack1.a(itemstack2.getItem()) || !itemstack1.f())) {
-                        this.resultSlots.setItem(0, ItemStack.EMPTY);
+                        org.bukkit.craftbukkit.event.CraftEventFactory.callPrepareAnvilEvent(getBukkitView(), ItemStack.EMPTY); // CraftBukkit
                         this.cost.set(0);
                         return;
                     }
@@ -229,7 +237,7 @@
                     }
 
                     if (flag2 && !flag1) {
-                        this.resultSlots.setItem(0, ItemStack.EMPTY);
+                        org.bukkit.craftbukkit.event.CraftEventFactory.callPrepareAnvilEvent(getBukkitView(), ItemStack.EMPTY); // CraftBukkit
                         this.cost.set(0);
                         return;
                     }
@@ -253,11 +261,11 @@
                 itemstack1 = ItemStack.EMPTY;
             }
 
-            if (b1 == i && b1 > 0 && this.cost.get() >= 40) {
-                this.cost.set(39);
+            if (b1 == i && b1 > 0 && this.cost.get() >= maximumRepairCost) { // CraftBukkit
+                this.cost.set(maximumRepairCost - 1); // CraftBukkit
             }
 
-            if (this.cost.get() >= 40 && !this.player.getAbilities().instabuild) {
+            if (this.cost.get() >= maximumRepairCost && !this.player.getAbilities().instabuild) { // CraftBukkit
                 itemstack1 = ItemStack.EMPTY;
             }
 
@@ -276,7 +284,8 @@
                 EnchantmentManager.a(map, itemstack1);
             }
 
-            this.resultSlots.setItem(0, itemstack1);
+            org.bukkit.craftbukkit.event.CraftEventFactory.callPrepareAnvilEvent(getBukkitView(), itemstack1); // CraftBukkit
+            updateInventory(); // CraftBukkit - SPIGOT-6686: Always send completed inventory to stay in sync with client
             this.d();
         }
     }
@@ -303,4 +312,18 @@
     public int m() {
         return this.cost.get();
     }
+
+    // CraftBukkit start
+    @Override
+    public CraftInventoryView getBukkitView() {
+        if (bukkitEntity != null) {
+            return bukkitEntity;
+        }
+
+        org.bukkit.craftbukkit.inventory.CraftInventory inventory = new org.bukkit.craftbukkit.inventory.CraftInventoryAnvil(
+                access.getLocation(), this.inputSlots, this.resultSlots, this);
+        bukkitEntity = new CraftInventoryView(this.player.getBukkitEntity(), inventory, this);
+        return bukkitEntity;
+    }
+    // CraftBukkit end
 }