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 */
019
020package org.apache.wiki.filters;
021
022import org.apache.wiki.api.core.Context;
023import org.apache.wiki.api.core.Engine;
024import org.apache.wiki.api.exceptions.FilterException;
025import org.apache.wiki.api.filters.BasePageFilter;
026import org.apache.wiki.event.WikiEventListener;
027import org.apache.wiki.event.WikiEventManager;
028import org.apache.wiki.event.WikiPageEvent;
029
030import java.util.Properties;
031import org.apache.wiki.security.EventUtil;
032
033/**
034  * Fires WikiPageEvents for page events.
035  * <p>
036  * Adding a PageEventFilter to the FilterManager will automatically attach an event delegate with the WikiEventManager to provide for
037  * firing and listener management. All that remains is then adding the listener to the filter via the WikiEventManager. This is quite
038  * simple:
039  * </p>
040  * <pre>
041  *    PageEventFilter filter = new PageEventFilter();
042  *    engine.getFilterManager().addPageFilter(filter,5000);
043  *    // attach listener to filter
044  *    WikiEventManager.addWikiEventListener(filter,listener);
045  * </pre>
046  * <p>
047  * This class provides convenience methods for adding and removing WikiEventListeners.
048  * </p>
049  *
050  * @see org.apache.wiki.event.WikiEventManager
051  */
052public class PageEventFilter extends BasePageFilter {
053
054    /**
055     * Called whenever a new PageFilter is instantiated and reset.
056     */
057    @Override
058    public void initialize( final Engine engine, final Properties properties ) throws FilterException {
059        super.initialize( engine, properties );
060    }
061
062    /**
063     * This method is called whenever a page has been loaded from the provider, but not yet been sent through the TranslatorReader.
064     * Note that you cannot do HTML translation here, because TranslatorReader is likely to escape it.
065     *
066     * @param wikiContext The current wikicontext.
067     * @param content WikiMarkup.
068     */
069    @Override
070    public String preTranslate( final Context wikiContext, final String content ) {
071        fireEvent( WikiPageEvent.PRE_TRANSLATE, wikiContext );
072        return content;
073    }
074
075
076    /**
077     * This method is called after a page has been fed through the TranslatorReader, so anything you are seeing here is translated content.
078     * If you want to do any of your own WikiMarkup2HTML translation, do it here.
079     */
080    @Override
081    public String postTranslate( final Context wikiContext, final String htmlContent ) {
082        fireEvent( WikiPageEvent.POST_TRANSLATE, wikiContext );
083        return htmlContent;
084    }
085
086
087    /**
088      * This method is called before the page has been saved to the PageProvider.
089      */
090    @Override
091    public String preSave( final Context wikiContext, final String content ) {
092        fireEvent( WikiPageEvent.PRE_SAVE, wikiContext );
093        return content;
094    }
095
096
097    /**
098      * This method is called after the page has been successfully saved. If the saving fails for any reason, then this method will not
099      * be called.
100      * <p>
101      * Since the result is discarded from this method, this is only useful for things like counters, etc.
102      */
103    @Override
104    public void postSave( final Context wikiContext, final String content ) {
105        fireEvent( WikiPageEvent.POST_SAVE, wikiContext );
106    }
107
108
109    // events processing .......................................................
110
111    /**
112     *  Registers a WikiEventListener with this instance. This is a convenience method.
113     *
114     * @param listener the event listener
115     */
116    public final synchronized void addWikiEventListener( final WikiEventListener listener ) {
117        WikiEventManager.addWikiEventListener( this, listener );
118    }
119
120    /**
121     *  Un-registers a WikiEventListener with this instance. This is a convenience method.
122     *
123     * @param listener the event listener
124     */
125    public final synchronized void removeWikiEventListener( final WikiEventListener listener ) {
126        WikiEventManager.removeWikiEventListener( this, listener );
127    }
128
129    /**
130     *  Fires a WikiPageEvent of the provided type and page name to all registered listeners. Only <tt>PAGE_LOCK</tt> and
131     *  <tt>PAGE_UNLOCK</tt> event types will fire an event; other event types are ignored.
132     *
133     * @see org.apache.wiki.event.WikiPageEvent
134     * @param type      the WikiPageEvent type to be fired.
135     * @param context   the WikiContext of the event.
136     */
137    protected final void fireEvent( final int type, final Context context ) {
138        if( WikiEventManager.isListening(this ) && WikiPageEvent.isValidType( type ) ) {
139            final WikiPageEvent event = new WikiPageEvent( context.getEngine(), type, context.getPage().getName() );
140            EventUtil.applyFrom(event, context);
141            WikiEventManager.fireEvent(this, event );
142        }
143    }
144
145}