AtomFeed.java

/* 
    Licensed to the Apache Software Foundation (ASF) under one
    or more contributor license agreements.  See the NOTICE file
    distributed with this work for additional information
    regarding copyright ownership.  The ASF licenses this file
    to you under the Apache License, Version 2.0 (the
    "License"); you may not use this file except in compliance
    with the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing,
    software distributed under the License is distributed on an
    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    KIND, either express or implied.  See the License for the
    specific language governing permissions and limitations
    under the License.  
 */
package org.apache.wiki.rss;

import java.io.IOException;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Date;
import java.util.Iterator;

import javax.servlet.ServletContext;

import org.apache.commons.lang.time.DateFormatUtils;
import org.jdom2.Element;
import org.jdom2.Namespace;
import org.jdom2.output.Format;
import org.jdom2.output.XMLOutputter;
import org.apache.wiki.Release;
import org.apache.wiki.WikiContext;
import org.apache.wiki.WikiEngine;
import org.apache.wiki.WikiPage;
import org.apache.wiki.api.exceptions.ProviderException;
import org.apache.wiki.attachment.Attachment;

/**
 *  Provides an Atom 1.0 standard feed, with enclosures.
 *
 */
public class AtomFeed extends Feed
{
    private Namespace m_atomNameSpace = Namespace.getNamespace("http://www.w3.org/2005/Atom");

    /**
     *  Defines a SimpleDateFormat string for RFC3339-formatted dates.
     */
    public static final String RFC3339FORMAT = "yyyy-MM-dd'T'HH:mm:ssZZ";

    /**
     *  Create a new AtomFeed for a given WikiContext.
     *  
     *  @param c A WikiContext.
     */
    public AtomFeed( WikiContext c )
    {
        super(c);
    }

    /**
     *   This is a bit complicated right now, as there is no proper metadata
     *   store in JSPWiki.
     *
     *   @return An unique feed ID.
     */
    private String getFeedID()
    {
        return m_wikiContext.getEngine().getBaseURL(); // FIXME: This is not a feed id
    }

    private String getEntryID( Entry e )
    {
        return e.getURL(); // FIXME: Not really a feed id!
    }

    private Collection getItems()
    {
        ArrayList<Element> list = new ArrayList<Element>();

        WikiEngine engine = m_wikiContext.getEngine();
        ServletContext servletContext = null;

        if( m_wikiContext.getHttpRequest() != null )
            servletContext = m_wikiContext.getHttpRequest().getSession().getServletContext();

        for( Iterator i = m_entries.iterator(); i.hasNext(); )
        {
            Entry e = (Entry)i.next();

            WikiPage p = e.getPage();

            Element entryEl = getElement("entry");

            //
            //  Mandatory elements
            //

            entryEl.addContent( getElement("id").setText( getEntryID(e)) );
            entryEl.addContent( getElement("title").setAttribute("type","html").setText( e.getTitle() ));
            entryEl.addContent( getElement("updated").setText( DateFormatUtils.formatUTC(p.getLastModified(),
                                                                                         RFC3339FORMAT )));
            //
            //  Optional elements
            //

            entryEl.addContent( getElement("author").addContent( getElement("name").setText( e.getAuthor() )));
            entryEl.addContent( getElement("link").setAttribute("rel","alternate").setAttribute("href",e.getURL()));
            entryEl.addContent( getElement("content").setAttribute("type","html").setText( e.getContent() ));

            //
            //  Check for enclosures
            //

            if( engine.getAttachmentManager().hasAttachments(p) && servletContext != null )
            {
                try
                {
                    Collection c = engine.getAttachmentManager().listAttachments(p);

                    for( Iterator a = c.iterator(); a.hasNext(); )
                    {
                        Attachment att = (Attachment) a.next();

                        Element attEl = getElement("link");
                        attEl.setAttribute( "rel","enclosure" );
                        attEl.setAttribute( "href", engine.getURL(WikiContext.ATTACH, att.getName(), null, true ) );
                        attEl.setAttribute( "length", Long.toString(att.getSize()) );
                        attEl.setAttribute( "type", getMimeType( servletContext, att.getFileName() ) );

                        entryEl.addContent( attEl );
                    }
                }
                catch( ProviderException ex )
                {
                    // FIXME: log.info("Can't get attachment data",ex);
                }
            }


            list.add( entryEl );
        }

        return list;
    }

    /**
     *  {@inheritDoc}
     */
    @Override
    public String getString()
    {
        Element root = getElement("feed");
        WikiEngine engine = m_wikiContext.getEngine();

        Date lastModified = new Date(0L);

        for( Iterator i = m_entries.iterator(); i.hasNext(); )
        {
            Entry e = (Entry)i.next();

            if( e.getPage().getLastModified().after(lastModified) )
                lastModified = e.getPage().getLastModified();
        }

        //
        //  Mandatory parts
        //
        root.addContent( getElement("title").setText( getChannelTitle() ) );
        root.addContent( getElement("id").setText(getFeedID()) );
        root.addContent( getElement("updated").setText(DateFormatUtils.formatUTC( lastModified,
                                                                                  RFC3339FORMAT ) ));

        //
        //  Optional
        //
        // root.addContent( getElement("author").addContent(getElement("name").setText(format())))
        root.addContent( getElement("link").setAttribute("href",engine.getBaseURL()));
        root.addContent( getElement("generator").setText("JSPWiki "+Release.VERSTR));

        String rssFeedURL  = engine.getURL(WikiContext.NONE, "rss.jsp",
                                           "page="+engine.encodeName(m_wikiContext.getPage().getName())+
                                           "&mode="+m_mode+
                                           "&type=atom",
                                           true );
        Element self = getElement("link").setAttribute("rel","self");
        self.setAttribute("href",rssFeedURL);
        root.addContent(self);

        //
        //  Items
        //

        root.addContent( getItems() );

        //
        //  aaand output
        //
        XMLOutputter output = new XMLOutputter();

        output.setFormat( Format.getPrettyFormat() );

        try
        {
            StringWriter res = new StringWriter();
            output.output( root, res );

            return res.toString();
        }
        catch( IOException e )
        {
            return null;
        }
    }

    private Element getElement( String name )
    {
        return new Element( name, m_atomNameSpace );
    }
}