ExprItem.java

package ch.njol.skript.expressions;

import org.bukkit.entity.Item;
import org.bukkit.event.Event;
import org.bukkit.inventory.ItemStack;
import org.jetbrains.annotations.Nullable;

import ch.njol.skript.aliases.ItemType;
import ch.njol.skript.classes.Changer.ChangeMode;
import ch.njol.skript.doc.Description;
import ch.njol.skript.doc.Examples;
import ch.njol.skript.doc.Name;
import ch.njol.skript.doc.Since;
import ch.njol.skript.expressions.base.EventValueExpression;
import ch.njol.skript.util.slot.Slot;

@Name("Item")
@Description("The item involved in an event, e.g. in a drop, dispense, pickup or craft event.")
@Examples({
	"on dispense:",
		"\titem is a clock",
		"\tset the time to 6:00"
})
@Since("<i>unknown</i> (before 2.1)")
public class ExprItem extends EventValueExpression<ItemStack> {

	static {
		register(ExprItem.class, ItemStack.class, "item");
	}

	public ExprItem() {
		super(ItemStack.class);
	}

	@Nullable
	private EventValueExpression<Item> item;

	@Nullable
	private EventValueExpression<Slot> slot;

	@Override
	@Nullable
	public Class<?>[] acceptChange(ChangeMode mode) {
		if (mode == ChangeMode.RESET)
			return null;
		item = new EventValueExpression<>(Item.class);
		if (item.init())
			return new Class[] {ItemType.class};
		item = null;
		slot = new EventValueExpression<>(Slot.class);
		if (slot.init())
			return new Class[] {ItemType.class};
		slot = null;
		return null;
	}

	@Override
	public void change(Event event, @Nullable Object[] delta, ChangeMode mode) {
		assert mode != ChangeMode.RESET;
		ItemType itemType = delta == null ? null : (ItemType) delta[0];
		Item item = this.item != null ? this.item.getSingle(event) : null;
		Slot slot = this.slot != null ? this.slot.getSingle(event) : null;
		if (item == null && slot == null)
			return;
		ItemStack itemstack = item != null ? item.getItemStack() : slot != null ? slot.getItem() : null;
		switch (mode) {
			case SET:
				assert itemType != null;
				itemstack = itemType.getRandom();
				break;
			case ADD:
			case REMOVE:
			case REMOVE_ALL:
				assert itemType != null;
				if (itemType.isOfType(itemstack)) {
					if (mode == ChangeMode.ADD)
						itemstack = itemType.addTo(itemstack);
					else if (mode == ChangeMode.REMOVE)
						itemstack = itemType.removeFrom(itemstack);
					else
						itemstack = itemType.removeAll(itemstack);
				}
				break;
			case DELETE:
				itemstack = null;
				if (item != null)
					item.remove();
				break;
			case RESET:
				assert false;
		}
		if (item != null && itemstack != null) {
			item.setItemStack(itemstack);
		} else if (slot != null) {
			slot.setItem(itemstack);
		} else {
			assert false;
		}
	}

}