/**
 * Copyright (c) 2011-2015, SpaceToad and the BuildCraft Team
 * http://www.mod-buildcraft.com
 * <p/>
 * BuildCraft is distributed under the terms of the Minecraft Mod Public
 * License 1.0, or MMPL. Please check the contents of the license located in
 * http://www.mod-buildcraft.com/MMPL-1.0.txt
 */
package buildcraft.transport;

import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import com.google.common.collect.ForwardingSet;

public class TravelerSet extends ForwardingSet<TravelingItem> {

	public boolean iterating;

	private final Set<TravelingItem> items = new HashSet<TravelingItem>();
	private final Set<TravelingItem> toLoad = new HashSet<TravelingItem>();
	private final Set<TravelingItem> toAdd = new HashSet<TravelingItem>();
	private final Set<TravelingItem> toRemove = new HashSet<TravelingItem>();
	private int delay = 0;
	private final PipeTransportItems transport;

	public TravelerSet(PipeTransportItems transport) {
		this.transport = transport;
	}

	@Override
	protected Set<TravelingItem> delegate() {
		return items;
	}

	@Override
	public boolean add(TravelingItem item) {
		if (iterating) {
			return toAdd.add(item);
		}
		item.setContainer(transport.container);
		items.add(item);
		return true;
	}

	@Override
	public boolean addAll(Collection<? extends TravelingItem> collection) {
		if (iterating) {
			return toAdd.addAll(collection);
		}
		return standardAddAll(collection);
	}

	@Override
	public boolean remove(Object object) {
		if (iterating) {
			return toRemove.add((TravelingItem) object);
		}
		return delegate().remove(object);
	}

	@Override
	public boolean removeAll(Collection<?> collection) {
		throw new UnsupportedOperationException();
	}

	@Override
	public boolean retainAll(Collection<?> collection) {
		throw new UnsupportedOperationException();
	}

	void scheduleLoad(TravelingItem item) {
		delay = 10;
		toLoad.add(item);
	}

	private void loadScheduledItems() {
		if (delay > 0) {
			delay--;
			return;
		}
		addAll(toLoad);
		toLoad.clear();
	}

	private void addScheduledItems() {
		addAll(toAdd);
		toAdd.clear();
	}

	public boolean scheduleRemoval(TravelingItem item) {
		return toRemove.add(item);
	}

	public boolean unscheduleRemoval(TravelingItem item) {
		return toRemove.remove(item);
	}

	void removeScheduledItems() {
		for (TravelingItem i : toRemove) {
			i.cleanup();
			items.remove(i);
		}
		toRemove.clear();
	}

	void flush() {
		loadScheduledItems();
		addScheduledItems();
		removeScheduledItems();
	}

	@Override
	public Iterator<TravelingItem> iterator() {
		return items.iterator();
	}

	@Override
	public void clear() {
		if (iterating) {
			toRemove.addAll(this);
		} else {
			items.clear();
		}
	}
}