/*
 * 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.cocoon.samples;

import java.io.IOException;
import java.io.Serializable;

import org.apache.cocoon.ProcessingException;
import org.apache.cocoon.caching.validity.EventValidity;
import org.apache.cocoon.caching.validity.NamedEvent;
import org.apache.cocoon.environment.ObjectModelHelper;
import org.apache.cocoon.environment.Request;
import org.apache.cocoon.template.JXTemplateGenerator;
import org.apache.excalibur.source.SourceValidity;
import org.xml.sax.SAXException;

/**
 * This is a sample generator to demonstrate the event aware caching.
 * We simply extend the JXTG.
 * @version $Id$
 */
public class EventAwareGenerator extends JXTemplateGenerator {

    /**
     * Generate the unique key for the cache.
     *
     * This key must be unique inside the space of this XSP page, it is used
     * to find the page contents in the cache (if getValidity says that the
     * contents are still valid).
     *
     * This method will be invoked before the getValidity() method.
     *
     * @return The generated key or null if the component
     *         is currently not cacheable.
     */
    public Serializable getKey() {
        final Request request = ObjectModelHelper.getRequest(this.objectModel);
        // for our test, pages having the same value of "pageKey" will share
        // the same cache location
        String key = request.getParameter("pageKey") ;
        return ((key==null||"".equals(key)) ? "one" : key);
    }

    /**
     * Generate the validity object, tells the cache how long to
     * keep contents having this key around.  In this case, it will 
     * be until an Event is retrieved matching the NamedEvent created below.
     *
     * Before this method can be invoked the getKey() method
     * will be invoked.
     *
     * @return The generated validity object or null if the
     *         component is currently not cacheable.
     */
    public SourceValidity getValidity() {
        final Request request = ObjectModelHelper.getRequest(this.objectModel);
        String key = request.getParameter("pageKey") ;
        return new EventValidity(
                   new NamedEvent(
                       (key==null||"".equals(key)) ? "one" : key));
    }


    /* (non-Javadoc)
     * @see org.apache.cocoon.generation.Generator#generate()
     */
    public void generate() 
    throws IOException, SAXException, ProcessingException {
        super.generate();
        // slowdown page generation.
        long DELAY_SECS = this.parameters.getParameterAsLong("DELAY_SECS", 2);
        try {
          Thread.sleep(DELAY_SECS * 1000L);
        } catch (InterruptedException ie) {
          // Not much that can be done...
        }
    }
}