/*
 * INESC-ID, Instituto de Engenharia de Sistemas e Computadores Investigação e Desevolvimento em Lisboa
 * Copyright 2013 INESC-ID and/or its affiliates and other
 * contributors as indicated by the @author tags. All rights reserved.
 * See the copyright.txt in the distribution for a full listing of
 * individual contributors.
 *
 * 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 3.0 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.infinispan.container.gmu;

import org.infinispan.container.versioning.EntryVersion;
import org.infinispan.container.versioning.InequalVersionComparisonResult;

import static org.infinispan.container.versioning.InequalVersionComparisonResult.*;

/**
 * // TODO: Document this
 *
 * @author Pedro Ruivo
 * @since 5.2
 */
public abstract class VersionBody<T> {
   private final T value;
   private VersionBody<T> previous;

   protected VersionBody(T value) {
      this.value = value;
   }

   protected static boolean isOlder(EntryVersion older, EntryVersion newer) {
      return older.compareTo(newer) == InequalVersionComparisonResult.BEFORE;
   }

   protected static boolean isOlderOrEquals(EntryVersion older, EntryVersion newer) {
      InequalVersionComparisonResult result = older.compareTo(newer);
      return result == BEFORE || result == BEFORE_OR_EQUAL || result == EQUAL;
   }

   protected static boolean isEqual(EntryVersion older, EntryVersion newer) {
      return older.compareTo(newer) == InequalVersionComparisonResult.EQUAL;
   }

   public T getValue() {
      return value;
   }

   public synchronized VersionBody<T> getPrevious() {
      return previous;
   }

   public synchronized void setPrevious(VersionBody<T> previous) {
      this.previous = previous;
   }

   public synchronized VersionBody<T> add(VersionBody<T> other) {
      if (previous == null) {
         previous = other;
         return null;
      } else if (previous.isOlder(other)) {
         other.setPrevious(previous);
         setPrevious(other);
         return null;
      } else if (previous.isEqual(other)) {
         previous.reincarnate(other);
         return null;
      }
      return previous;
   }

   public synchronized VersionBody expire(long now) {
      if (previous == null) {
         return null;
      }
      if (previous.isExpired(now)) {
         previous = previous.getPrevious();
         return this;
      }
      return previous;
   }

   @Override
   public String toString() {
      return "VersionBody{" +
            "value=" + value +
            '}';
   }

   public abstract EntryVersion getVersion();

   public abstract boolean isOlder(VersionBody<T> otherBody);

   public abstract boolean isEqual(VersionBody<T> otherBody);

   public abstract boolean isOlderOrEquals(EntryVersion entryVersion);

   public abstract boolean isRemove();

   public abstract void reincarnate(VersionBody<T> other);

   public abstract VersionBody<T> gc(EntryVersion minVersion);

   protected abstract boolean isExpired(long now);

}