001/*
002    Licensed to the Apache Software Foundation (ASF) under one
003    or more contributor license agreements.  See the NOTICE file
004    distributed with this work for additional information
005    regarding copyright ownership.  The ASF licenses this file
006    to you under the Apache License, Version 2.0 (the
007    "License"); you may not use this file except in compliance
008    with the License.  You may obtain a copy of the License at
009
010       http://www.apache.org/licenses/LICENSE-2.0
011
012    Unless required by applicable law or agreed to in writing,
013    software distributed under the License is distributed on an
014    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015    KIND, either express or implied.  See the License for the
016    specific language governing permissions and limitations
017    under the License.   
018 */
019package org.apache.wiki.pages;
020
021import org.apache.logging.log4j.LogManager;
022import org.apache.logging.log4j.Logger;
023import org.apache.wiki.api.core.Page;
024
025import java.io.Serializable;
026import java.util.Comparator;
027import java.util.Date;
028
029/**
030 *  Compares the lastModified date of its arguments.  Both o1 and o2 MUST be WikiPage objects, or else you will receive a ClassCastException.
031 *  <p>
032 *  If the lastModified date is the same, then the next key is the page name. If the page name is also equal, then returns 0 for equality.
033 */
034public class PageTimeComparator implements Comparator< Page >, Serializable {
035    
036    private static final long serialVersionUID = 0L;
037    private static final Logger log = LogManager.getLogger( PageTimeComparator.class );
038
039    /**
040     *  {@inheritDoc}
041     */
042    public int compare( final Page p1, final Page p2 ) {
043        if( p1 == null || p2 == null ) {
044            log.error( "W1 or W2 is NULL in PageTimeComparator!");
045            return 0; // FIXME: Is this correct?
046        }
047
048        final Date w1LastMod = p1.getLastModified();
049        final Date w2LastMod = p2.getLastModified();
050
051        if( w1LastMod == null ) {
052            log.error( "NULL MODIFY DATE WITH " + p1.getName() );
053            return 0;
054        } else if( w2LastMod == null ) {
055            log.error( "NULL MODIFY DATE WITH " + p2.getName() );
056            return 0;
057        }
058
059        // This gets most recent on top
060        final int timecomparison = w2LastMod.compareTo( w1LastMod );
061        if( timecomparison == 0 ) {
062            return p1.compareTo( p2 );
063        }
064
065        return timecomparison;
066    }
067
068}