    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.tags;
    020
    021import org.apache.logging.log4j.LogManager;
    022import org.apache.logging.log4j.Logger;
    023import org.apache.wiki.api.core.ContextEnum;
    024import org.apache.wiki.pages.PageManager;
    025import org.apache.wiki.util.TextUtil;
    026
    027import jakarta.servlet.http.HttpSession;
    028import jakarta.servlet.jsp.JspWriter;
    029import java.io.IOException;
    030import java.io.Serializable;
    031import java.util.LinkedList;
    032
    033/**
    034 * Implement a "breadcrumb" (most recently visited) trail.  This tag can be added to any view jsp page.
    035 * Separate breadcrumb trails are not tracked across multiple browser windows.<br>
    036 * The optional attributes are:
    037 * <p>
    038 * <b>maxpages</b>, the number of pages to store, 10 by default<br>
    039 * <b>separator</b>, the separator string to use between pages, " | " by default<br>
    040 * </p>
    041 *
    042 * <p>
    043 * This class is implemented by storing a breadcrumb trail, which is a
    044 * fixed size queue, into a session variable "breadCrumbTrail".
    045 * This queue is displayed as a series of links separated by a separator
    046 * character.
    047 * </p>
    048 */
    049public class BreadcrumbsTag extends WikiTagBase
    050{
    051    private static final long serialVersionUID = 0L;
    052
    053    private static final Logger LOG = LogManager.getLogger(BreadcrumbsTag.class);
    054    /** The name of the session attribute representing the breadcrumbtrail */
    055    public static final String BREADCRUMBTRAIL_KEY = "breadCrumbTrail";
    056    private int m_maxQueueSize = 11;
    057    private String m_separator = ", ";
    058
    059    /**
    060     *  {@inheritDoc}
    061     */
    062    @Override
    063    public void initTag()
    064    {
    065        super.initTag();
    066        m_maxQueueSize = 11;
    067        m_separator = ", ";
    068    }
    069
    070    /**
    071     *  Returns the maxpages.  This may differ from what was set by setMaxpages().
    072     *
    073     *  @return The current size of the pages.
    074     */
    075    public int getMaxpages()
    076    {
    077        return m_maxQueueSize;
    078    }
    079
    080    /**
    081     *  Sets how many pages to show.
    082     *
    083     *  @param maxpages The amount.
    084     */
    085    public void setMaxpages( final int maxpages)
    086    {
    087        m_maxQueueSize = maxpages + 1;
    088    }
    089
    090    /**
    091     *  Get the separator string.
    092     *
    093     *  @return The string set in setSeparator()
    094     */
    095    public String getSeparator()
    096    {
    097        return m_separator;
    098    }
    099
    100    /**
    101     *  Set the separator string.
    102     *
    103     *  @param separator A string which separates the page names.
    104     */
    105    public void setSeparator( final String separator)
    106    {
    107        m_separator = TextUtil.replaceEntities( separator );
    108    }
    109
    110    /**
    111     *  {@inheritDoc}
    112     */
    113    @Override
    114    public int doWikiStartTag() throws IOException {
    115        final HttpSession session = pageContext.getSession();
    116        FixedQueue trail = (FixedQueue) session.getAttribute(BREADCRUMBTRAIL_KEY);
    117        final String page = m_wikiContext.getPage().getName();
    118
    119        if( trail == null ) {
    120            trail = new FixedQueue(m_maxQueueSize);
    121        } else {
    122            //  check if page still exists (could be deleted/renamed by another user)
    123            for (int i = 0;i<trail.size();i++) {
    124                if( !m_wikiContext.getEngine().getManager( PageManager.class ).wikiPageExists( trail.get( i ) ) ) {
    125                    trail.remove(i);
    126                }
    127            }
    128        }
    129
    130        if( m_wikiContext.getRequestContext().equals( ContextEnum.PAGE_VIEW.getRequestContext() ) ) {
    131            if( m_wikiContext.getEngine().getManager( PageManager.class ).wikiPageExists( page ) ) {
    132                if( trail.isEmpty() ) {
    133                    trail.pushItem( page );
    134                } else {
    135                    // Don't add the page to the queue if the page was just refreshed
    136                    if( !trail.getLast().equals( page ) ) {
    137                        trail.pushItem( page );
    138                    }
    139                }
    140            } else {
    141                LOG.debug( "didn't add page because it doesn't exist: " + page );
    142            }
    143        }
    144
    145        session.setAttribute(BREADCRUMBTRAIL_KEY, trail);
    146
    147        //
    148        //  Print out the breadcrumb trail
    149        //
    150
    151        // FIXME: this code would be much simpler if we could just output the [pagename] and then use the
    152        // wiki engine to output the appropriate wikilink
    153
    154        final JspWriter out     = pageContext.getOut();
    155        final int queueSize     = trail.size();
    156        final String linkclass  = "wikipage";
    157        String curPage;
    158
    159        for( int i = 0; i < queueSize - 1; i++ ) {
    160            curPage = trail.get(i);
    161
    162            //FIXME: I can't figure out how to detect the appropriate jsp page to put here, so I hard coded Wiki.jsp
    163            //This breaks when you view an attachment metadata page
    164            out.print( "<a class=\"" + linkclass + "\" href=\"" + m_wikiContext.getViewURL(curPage) + "\">" +
    165                       TextUtil.replaceEntities( curPage ) +
    166                       "</a>" );
    167
    168            if( i < queueSize - 2 ) {
    169                out.print(m_separator);
    170            }
    171        }
    172
    173        return SKIP_BODY;
    174    }
    175
    176    /**
    177     * Extends the LinkedList class to provide a fixed-size queue implementation
    178     */
    179    public static class FixedQueue extends LinkedList< String > implements Serializable {
    180        private final int m_size;
    181        private static final long serialVersionUID = 0L;
    182
    183        FixedQueue( final int size ) {
    184            m_size = size;
    185        }
    186
    187        String pushItem( final String o ) {
    188            add( o );
    189            if( size() > m_size ) {
    190                return removeFirst();
    191            }
    192
    193            return null;
    194        }
    195
    196        /**
    197         * @param pageName the page to be deleted from the breadcrumb
    198         */
    199        public void removeItem( final String pageName ) {
    200            for( int i = 0; i < size(); i++ ) {
    201                final String page = get( i );
    202                if( page != null && page.equals( pageName ) ) {
    203                    remove( page );
    204                }
    205            }
    206        }
    207
    208    }
    209}
    210