PaperMC/nms-patches/Container.patch

--- a/net/minecraft/server/Container.java
+++ b/net/minecraft/server/Container.java
@@ -7,6 +7,18 @@
 import java.util.Set;
 import javax.annotation.Nullable;
 
+// CraftBukkit start
+import com.google.common.base.Preconditions;
+import java.util.HashMap;
+import java.util.Map;
+import org.bukkit.craftbukkit.inventory.CraftInventory;
+import org.bukkit.craftbukkit.inventory.CraftItemStack;
+import org.bukkit.event.Event.Result;
+import org.bukkit.event.inventory.InventoryDragEvent;
+import org.bukkit.event.inventory.InventoryType;
+import org.bukkit.inventory.InventoryView;
+// CraftBukkit end
+
 public abstract class Container {
 
     public NonNullList<ItemStack> items = NonNullList.a();
@@ -21,6 +33,27 @@
     private final List<ICrafting> listeners = Lists.newArrayList();
     private final Set<EntityHuman> k = Sets.newHashSet();
 
+    // CraftBukkit start
+    public boolean checkReachable = true;
+    public abstract InventoryView getBukkitView();
+    public void transferTo(Container other, org.bukkit.craftbukkit.entity.CraftHumanEntity player) {
+        InventoryView source = this.getBukkitView(), destination = other.getBukkitView();
+        ((CraftInventory) source.getTopInventory()).getInventory().onClose(player);
+        ((CraftInventory) source.getBottomInventory()).getInventory().onClose(player);
+        ((CraftInventory) destination.getTopInventory()).getInventory().onOpen(player);
+        ((CraftInventory) destination.getBottomInventory()).getInventory().onOpen(player);
+    }
+    private IChatBaseComponent title;
+    public final IChatBaseComponent getTitle() {
+        Preconditions.checkState(this.title != null, "Title not set");
+        return this.title;
+    }
+    public final void setTitle(IChatBaseComponent title) {
+        Preconditions.checkState(this.title == null, "Title already set");
+        this.title = title;
+    }
+    // CraftBukkit end
+
     protected Container(@Nullable Containers<?> containers, int i) {
         this.e = containers;
         this.windowId = i;
@@ -202,6 +235,7 @@
                     k = playerinventory.getCarried().getCount();
                     Iterator iterator = this.i.iterator();
 
+                    Map<Integer, ItemStack> draggedSlots = new HashMap<Integer, ItemStack>(); // CraftBukkit - Store slots from drag in map (raw slot id -> new stack)
                     while (iterator.hasNext()) {
                         Slot slot1 = (Slot) iterator.next();
                         ItemStack itemstack3 = playerinventory.getCarried();
@@ -217,12 +251,48 @@
                             }
 
                             k -= itemstack4.getCount() - j1;
-                            slot1.set(itemstack4);
+                            // slot1.set(itemstack4);
+                            draggedSlots.put(slot1.rawSlotIndex, itemstack4); // CraftBukkit - Put in map instead of setting
                         }
                     }
 
-                    itemstack2.setCount(k);
-                    playerinventory.setCarried(itemstack2);
+                    // CraftBukkit start - InventoryDragEvent
+                    InventoryView view = getBukkitView();
+                    org.bukkit.inventory.ItemStack newcursor = CraftItemStack.asCraftMirror(itemstack2);
+                    newcursor.setAmount(k);
+                    Map<Integer, org.bukkit.inventory.ItemStack> eventmap = new HashMap<Integer, org.bukkit.inventory.ItemStack>();
+                    for (Map.Entry<Integer, ItemStack> ditem : draggedSlots.entrySet()) {
+                        eventmap.put(ditem.getKey(), CraftItemStack.asBukkitCopy(ditem.getValue()));
+                    }
+
+                    // It's essential that we set the cursor to the new value here to prevent item duplication if a plugin closes the inventory.
+                    ItemStack oldCursor = playerinventory.getCarried();
+                    playerinventory.setCarried(CraftItemStack.asNMSCopy(newcursor));
+
+                    InventoryDragEvent event = new InventoryDragEvent(view, (newcursor.getType() != org.bukkit.Material.AIR ? newcursor : null), CraftItemStack.asBukkitCopy(oldCursor), this.dragType == 1, eventmap);
+                    entityhuman.world.getServer().getPluginManager().callEvent(event);
+
+                    // Whether or not a change was made to the inventory that requires an update.
+                    boolean needsUpdate = event.getResult() != Result.DEFAULT;
+
+                    if (event.getResult() != Result.DENY) {
+                        for (Map.Entry<Integer, ItemStack> dslot : draggedSlots.entrySet()) {
+                            view.setItem(dslot.getKey(), CraftItemStack.asBukkitCopy(dslot.getValue()));
+                        }
+                        // The only time the carried item will be set to null is if the inventory is closed by the server.
+                        // If the inventory is closed by the server, then the cursor items are dropped.  This is why we change the cursor early.
+                        if (playerinventory.getCarried() != null) {
+                            playerinventory.setCarried(CraftItemStack.asNMSCopy(event.getCursor()));
+                            needsUpdate = true;
+                        }
+                    } else {
+                        playerinventory.setCarried(oldCursor);
+                    }
+
+                    if (needsUpdate && entityhuman instanceof EntityPlayer) {
+                        ((EntityPlayer) entityhuman).updateInventory(this);
+                    }
+                    // CraftBukkit end
                 }
 
                 this.d();
@@ -239,8 +309,11 @@
                 if (i == -999) {
                     if (!playerinventory.getCarried().isEmpty()) {
                         if (j == 0) {
-                            entityhuman.drop(playerinventory.getCarried(), true);
+                            // CraftBukkit start
+                            ItemStack carried = playerinventory.getCarried();
                             playerinventory.setCarried(ItemStack.b);
+                            entityhuman.drop(carried, true);
+                            // CraftBukkit start
                         }
 
                         if (j == 1) {
@@ -328,6 +401,15 @@
                         }
 
                         slot2.d();
+                        // CraftBukkit start - Make sure the client has the right slot contents
+                        if (entityhuman instanceof EntityPlayer && slot2.getMaxStackSize() != 64) {
+                            ((EntityPlayer) entityhuman).playerConnection.sendPacket(new PacketPlayOutSetSlot(this.windowId, slot2.rawSlotIndex, slot2.getItem()));
+                            // Updating a crafting inventory makes the client reset the result slot, have to send it again
+                            if (this.getBukkitView().getType() == InventoryType.WORKBENCH || this.getBukkitView().getType() == InventoryType.CRAFTING) {
+                                ((EntityPlayer) entityhuman).playerConnection.sendPacket(new PacketPlayOutSetSlot(this.windowId, 0, this.getSlot(0).getItem()));
+                            }
+                        }
+                        // CraftBukkit end
                     }
                 }
             } else if (inventoryclicktype == InventoryClickType.SWAP) {
@@ -430,8 +512,11 @@
         PlayerInventory playerinventory = entityhuman.inventory;
 
         if (!playerinventory.getCarried().isEmpty()) {
-            entityhuman.drop(playerinventory.getCarried(), false);
+            // CraftBukkit start - SPIGOT-4556
+            ItemStack carried = playerinventory.getCarried();
             playerinventory.setCarried(ItemStack.b);
+            entityhuman.drop(carried, false);
+            // CraftBukkit end
         }
 
     }