Add InventoryPreMoveItemEvent

sparklypaper-api/src/main/java/net/sparklypower/sparklypaper/event/inventory/InventoryPreMoveItemEvent.java

@@ -0,0 +1,85 @@
+package net.sparklypower.sparklypaper.event.inventory;
+
+import org.bukkit.event.Cancellable;
+import org.bukkit.event.Event;
+import org.bukkit.event.HandlerList;
+import org.bukkit.inventory.Inventory;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Called when some entity or block (e.g. hopper) tries to move items directly
+ * from one inventory to another.
+ * <p>
+ * This event is called before InventoryMoveItemEvent, and is called before the
+ * item within the container is modified to match the pull/push stack count.
+ */
+public class InventoryPreMoveItemEvent extends Event implements Cancellable {
+
+    private static final HandlerList HANDLER_LIST = new HandlerList();
+
+    private final Inventory sourceInventory;
+    private final Inventory destinationInventory;
+    private final boolean didSourceInitiate;
+
+    private boolean cancelled;
+
+    @ApiStatus.Internal
+    public InventoryPreMoveItemEvent(@NotNull final Inventory sourceInventory, @NotNull final Inventory destinationInventory, final boolean didSourceInitiate) {
+        this.sourceInventory = sourceInventory;
+        this.destinationInventory = destinationInventory;
+        this.didSourceInitiate = didSourceInitiate;
+    }
+
+    /**
+     * Gets the Inventory that the ItemStack is being taken from
+     *
+     * @return Inventory that the ItemStack is being taken from
+     */
+    @NotNull
+    public Inventory getSource() {
+        return this.sourceInventory;
+    }
+
+    /**
+     * Gets the Inventory that the ItemStack is being put into
+     *
+     * @return Inventory that the ItemStack is being put into
+     */
+    @NotNull
+    public Inventory getDestination() {
+        return this.destinationInventory;
+    }
+
+    /**
+     * Gets the Inventory that initiated the transfer. This will always be
+     * either the destination or source Inventory.
+     *
+     * @return Inventory that initiated the transfer
+     */
+    @NotNull
+    public Inventory getInitiator() {
+        return this.didSourceInitiate ? this.sourceInventory : this.destinationInventory;
+    }
+
+    @Override
+    public boolean isCancelled() {
+        return this.cancelled;
+    }
+
+    @Override
+    public void setCancelled(boolean cancel) {
+        this.cancelled = cancel;
+    }
+
+    @NotNull
+    @Override
+    public HandlerList getHandlers() {
+        return HANDLER_LIST;
+    }
+
+    @NotNull
+    public static HandlerList getHandlerList() {
+        return HANDLER_LIST;
+    }
+}

sparklypaper-server/minecraft-patches/sources/net/minecraft/world/level/block/entity/HopperBlockEntity.java.patch

@@ -1,5 +1,69 @@
 --- a/net/minecraft/world/level/block/entity/HopperBlockEntity.java
 +++ b/net/minecraft/world/level/block/entity/HopperBlockEntity.java
+@@ -228,7 +_,15 @@
+         for (int i = 0; i < hopper.getContainerSize(); ++i) {
+             final ItemStack item = hopper.getItem(i);
+             if (!item.isEmpty()) {
++                // SparklyPaper start - InventoryPreMoveItemEvent
++                if (!foundItem) {
++                    // Only call it once per push, instead of per item
++                    if (!callPushPreMoveEvent(destination, hopper))
++                        return false;
++                }
++                // SparklyPaper end
+                 foundItem = true;
++
+                 ItemStack origItemStack = item;
+                 ItemStack movedItem = origItemStack;
+ 
+@@ -268,6 +_,10 @@
+     }
+ 
+     private static boolean hopperPull(final Level level, final Hopper hopper, final Container container, ItemStack origItemStack, final int i) {
++        // SparklyPaper start - InventoryPreMoveItemEvent
++        if (!callPullPreMoveEvent(hopper, container))
++            return true;
++        // SparklyPaper end
+         ItemStack movedItem = origItemStack;
+         final int originalItemCount = origItemStack.getCount();
+         final int movedItemCount = Math.min(level.spigotConfig.hopperAmount, originalItemCount);
+@@ -357,6 +_,36 @@
+         }
+     }
+ 
++    // SparklyPaper start - InventoryPreMoveItemEvent
++    private static boolean callPushPreMoveEvent(Container destination, HopperBlockEntity hopper) {
++        final org.bukkit.inventory.Inventory destinationInventory = getInventory(destination);
++        final net.sparklypower.sparklypaper.event.inventory.InventoryPreMoveItemEvent event = new net.sparklypower.sparklypaper.event.inventory.InventoryPreMoveItemEvent(
++            hopper.getOwner(false).getInventory(),
++            destinationInventory,
++            true
++        );
++        final boolean result = event.callEvent();
++        if (!result) {
++            applyCooldown(hopper);
++        }
++
++        return result;
++    }
++
++    private static boolean callPullPreMoveEvent(final Hopper hopper, final Container container) {
++        final org.bukkit.inventory.Inventory sourceInventory = getInventory(container);
++        final org.bukkit.inventory.Inventory destination = getInventory(hopper);
++
++        // Mirror is safe as no plugins ever use this item
++        final net.sparklypower.sparklypaper.event.inventory.InventoryPreMoveItemEvent event = new net.sparklypower.sparklypaper.event.inventory.InventoryPreMoveItemEvent(sourceInventory, destination, false);
++        final boolean result = event.callEvent();
++        if (!result)
++            applyCooldown(hopper);
++
++        return result;
++    }
++    // SparklyPaper end
++
+     private static org.bukkit.inventory.Inventory getInventory(final Container container) {
+         final org.bukkit.inventory.Inventory sourceInventory;
+         if (container instanceof net.minecraft.world.CompoundContainer compoundContainer) {
 @@ -424,6 +_,7 @@
          } else {
              Direction opposite = blockEntity.facing.getOpposite();