org.bukkit.event.inventory.InventoryDragEvent Maven / Gradle / Ivy

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package org.bukkit.event.inventory;

import com.google.common.collect.ImmutableSet;
import org.apache.commons.lang.Validate;
import org.bukkit.Location;
import org.bukkit.entity.HumanEntity;
import org.bukkit.entity.Player;
import org.bukkit.event.HandlerList;
import org.bukkit.inventory.Inventory;
import org.bukkit.inventory.InventoryView;
import org.bukkit.inventory.ItemStack;
import org.bukkit.plugin.Plugin;
import org.bukkit.scheduler.BukkitScheduler;

import java.util.Collections;
import java.util.Map;
import java.util.Set;

/**
 * This event is called when the player drags an item in their cursor across
 * the inventory. The ItemStack is distributed across the slots the
 * HumanEntity dragged over. The method of distribution is described by the
 * DragType returned by {@link #getType()}.
 * 
 * Canceling this event will result in none of the changes described in
 * {@link #getNewItems()} being applied to the Inventory.
 * 

 * Because InventoryDragEvent occurs within a modification of the Inventory,
 * not all Inventory related methods are safe to use.
 * 

 * The following should never be invoked by an EventHandler for
 * InventoryDragEvent using the HumanEntity or InventoryView associated with
 * this event.
 * 

 * {@link HumanEntity#closeInventory()}
 * 
{@link HumanEntity#openInventory(Inventory)}
 * 
{@link HumanEntity#openWorkbench(Location, boolean)}
 * 
{@link HumanEntity#openEnchanting(Location, boolean)}
 * 
{@link InventoryView#close()}
 * 
 * To invoke one of these methods, schedule a task using
 * {@link BukkitScheduler#runTask(Plugin, Runnable)}, which will run the task
 * on the next tick.  Also be aware that this is not an exhaustive list, and
 * other methods could potentially create issues as well.
 * 
 * Assuming the EntityHuman associated with this event is an instance of a
 * Player, manipulating the MaxStackSize or contents of an Inventory will
 * require an Invocation of {@link Player#updateInventory()}.
 * 

 * Any modifications to slots that are modified by the results of this
 * InventoryDragEvent will be overwritten. To change these slots, this event
 * should be cancelled and the changes applied. Alternatively, scheduling a
 * task using {@link BukkitScheduler#runTask(Plugin, Runnable)}, which would
 * execute the task on the next tick, would work as well.
 */
public class InventoryDragEvent extends InventoryInteractEvent {
  private static final HandlerList handlers = new HandlerList();
  private final DragType type;
  private final Map addedItems;
  private final Set containerSlots;
  private final ItemStack oldCursor;
  private ItemStack newCursor;

  public InventoryDragEvent(InventoryView what, ItemStack newCursor, ItemStack oldCursor, boolean right, Map slots) {
    super(what);

    Validate.notNull(oldCursor);
    Validate.notNull(slots);

    type = right ? DragType.SINGLE : DragType.EVEN;
    this.newCursor = newCursor;
    this.oldCursor = oldCursor;
    this.addedItems = slots;
    ImmutableSet.Builder b = ImmutableSet.builder();
    for (Integer slot : slots.keySet()) {
      b.add(what.convertSlot(slot));
    }
    this.containerSlots = b.build();
  }

  public static HandlerList getHandlerList() {
    return handlers;
  }

  /**
   * Gets all items to be added to the inventory in this drag.
   *
   * @return map from raw slot id to new ItemStack
   */
  public Map getNewItems() {
    return Collections.unmodifiableMap(addedItems);
  }

  /**
   * Gets the raw slot ids to be changed in this drag.
   *
   * @return list of raw slot ids, suitable for getView().getItem(int)
   */
  public Set getRawSlots() {
    return addedItems.keySet();
  }

  /**
   * Gets the slots to be changed in this drag.
   *
   * @return list of converted slot ids, suitable for {@link
   * org.bukkit.inventory.Inventory#getItem(int)}.
   */
  public Set getInventorySlots() {
    return containerSlots;
  }

  /**
   * Gets the result cursor after the drag is done. The returned value is
   * mutable.
   *
   * @return the result cursor
   */
  public ItemStack getCursor() {
    return newCursor;
  }

  /**
   * Sets the result cursor after the drag is done.
   * 

   * Changing this item stack changes the cursor item. Note that changing
   * the affected "dragged" slots does not change this ItemStack, nor does
   * changing this ItemStack affect the "dragged" slots.
   *
   * @param newCursor the new cursor ItemStack
   */
  public void setCursor(ItemStack newCursor) {
    this.newCursor = newCursor;
  }

  /**
   * Gets an ItemStack representing the cursor prior to any modifications
   * as a result of this drag.
   *
   * @return the original cursor
   */
  public ItemStack getOldCursor() {
    return oldCursor.clone();
  }

  /**
   * Gets the DragType that describes the behavior of ItemStacks placed
   * after this InventoryDragEvent.
   * 
   * The ItemStacks and the raw slots that they're being applied to can be
   * found using {@link #getNewItems()}.
   *
   * @return the DragType of this InventoryDragEvent
   */
  public DragType getType() {
    return type;
  }

  @Override
  public HandlerList getHandlers() {
    return handlers;
  }
}