package org.moparscape.msc.gs.util;

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

import org.moparscape.msc.gs.model.Entity;


/**
 * This class is a collection which is backed by 3 seperate Sets.
 * 
 * These sets control the state of this collection.
 * 
 * To update this collections current state, you need to explicity call the
 * update method.
 * 
 * The purpose of this collection is to seperate new values added to this
 * collection untill the update method has been called. Removal of entities will
 * NOT take effect until the update method is called. This is so we can see what
 * is being removed (and in cases this is required by the server) to handle them
 * specially.
 * 
 */

public class StatefulEntityCollection<T extends Entity> {

    private Set<T> entitiesToRemove = new HashSet<T>();
    private Set<T> knownEntities = new HashSet<T>();
    private Set<T> newEntities = new HashSet<T>();

    // We need to keep these in the order they logged in, currently it doesn't
    // seem to?

    public void add(Collection<T> entities) {
	newEntities.addAll(entities);
    }

    public void add(T entity) {
	newEntities.add(entity);
    }

    public boolean changed() {
	return !entitiesToRemove.isEmpty() || !newEntities.isEmpty();
    }

    public boolean contains(T entity) {
	return newEntities.contains(entity) || knownEntities.contains(entity);
    }

    public Collection<T> getAllEntities() {
	Set<T> temp = new HashSet<T>();
	temp.addAll(newEntities);
	temp.addAll(knownEntities);
	return temp;
    }

    public Collection<T> getKnownEntities() {
	return knownEntities;
    }

    public Collection<T> getNewEntities() {
	return newEntities;
    }

    public Collection<T> getRemovingEntities() {
	return entitiesToRemove;
    }

    public boolean isRemoving(T entity) {
    	return entitiesToRemove.contains(entity);
    }

    public void remove(T entity) {
    	entitiesToRemove.add(entity);
    }

    public void update() {
		knownEntities.removeAll(entitiesToRemove);
		knownEntities.addAll(newEntities);
		newEntities.clear();
		entitiesToRemove.clear();
    }

}