/*
 * Copyright (C) 2011 eXo Platform SAS.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.exoplatform.portal.mop.description;

import java.io.Serializable;
import java.util.Objects;
import java.util.concurrent.atomic.AtomicLong;

import org.exoplatform.portal.mop.Described;

/**
 * @author <a href="mailto:julien.viet@exoplatform.com">Julien Viet</a>
 */
public class CacheValue implements Serializable {
  
    public static final CacheValue NULL_VALUE = new CacheValue();

    /** . */
    private static final AtomicLong SEQUENCE = new AtomicLong();

    /** . */
    final CacheKey origin;

    /** . */
    final long serial;

    /** . */
    final Described.State state;

    private CacheValue() {
      state = null;
      serial = 0;
      origin = null;
    }

    public CacheValue(CacheKey origin, long serial, Described.State state) {
        this.origin = origin;
        this.serial = serial;
        this.state = state;
    }

    public CacheValue(Described.State state) {
        this.origin = null;
        this.serial = SEQUENCE.incrementAndGet();
        this.state = state;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof CacheValue)) return false;

        CacheValue that = (CacheValue) o;

        if (serial != that.serial) return false;
        return origin != null ? origin.equals(that.origin) : that.origin == null;

    }

    @Override
    public int hashCode() {
        int result = origin != null ? origin.hashCode() : 0;
        result = 31 * result + (int) (serial ^ (serial >>> 32));
        return result;
    }
}
