/*
 *                 Sun Public License Notice
 * 
 * The contents of this file are subject to the Sun Public License
 * Version 1.0 (the "License"). You may not use this file except in
 * compliance with the License. A copy of the License is available at
 * http://www.sun.com/
 * 
 * The Original Code is NetBeans. The Initial Developer of the Original
 * Code is Sun Microsystems, Inc. Portions Copyright 1997-2003 Sun
 * Microsystems, Inc. All Rights Reserved.
 */

package org.netbeans.modules.web.monitor.catalina;

import org.apache.catalina.InstanceEvent;
import javax.servlet.*;
import java.util.*;
import java.lang.reflect.*;

/**
 * DispatchListener.java
 * 
 * This class is used to allow the HTTP Monitor to record data about
 * dispatched requests on pre-Servlet 2.4 Catalina Servlet Containers.
 * This class listens for Catalina InstanceEvents, which are fired
 * when the RequestDispatcher sends a request to a resource. It uses
 * reflection to invoke a method on the MonitorFilter class. 
 * 
 *
 * Created: Mon Feb 18 12:15:52 2002
 *
 * @author Ana von Klopp
 */
 

public class DispatchListener implements org.apache.catalina.InstanceListener {
    
    private final static boolean debug = false;
     
    public DispatchListener() {
	if(debug) log(" Creating the listener"); //NOI18N
    }

    /**
     * Acknowledge the occurrence of the specified event.
     *
     * @param event InstanceEvent that has occurred
     */
    public void instanceEvent(InstanceEvent event) {
	
	//if(debug) log("instanceEvent() : start"); //NOI18N
	
	if((event.getType().equals(InstanceEvent.BEFORE_DISPATCH_EVENT)) || 
	   (event.getType().equals(InstanceEvent.AFTER_DISPATCH_EVENT))) {
	    

	    if(debug) log(event.getType());
	    
	    ServletRequest request = event.getRequest();
	    if(request == null) {
		if(debug) log("Request missing, return"); //NOI18N
		return;
	    }

	    Filter filter =
		(Filter)event.getRequest().getAttribute("netbeans.monitor.filter"); //NOI18N
	    if(filter == null) { 
		if(debug) log("Cannot find the filter, return"); //NOI18N
		return;
	    }

	    // The servlet attribute is set by the valve for the 
	    // original request. We set it here also since there 
	    // will be a different processing servlet for the dispatched 
	    // event. 
	    Servlet servlet = event.getServlet();
	    if(servlet != null) {
		request.setAttribute("netbeans.monitor.servlet", //NOI18N
				     servlet);
	    }

	    // The objective is to invoke the 
	    // MonitorFilter.handleDispatchedBefore(ServletRequest req)
	    // method or the 
	    // MonitorFilter.handleDispatchedAfter(ServletRequest req)
	    // method. 

	    Class clazz = filter.getClass();
	    Class[] argtypes = new Class[1];
	    Object[] args = new Object[1]; 
	    String methodName;

	    try {
		argtypes[0] = 
		    Class.forName("javax.servlet.ServletRequest"); //NOI18N
	    }
	    catch(ClassNotFoundException cnfe) {
		if(debug) log("Couldn't create the javax.servlet classes, returning"); //NOI18N
		return;
	    }

	    args[0] = request;

	    if(event.getType().equals(InstanceEvent.BEFORE_DISPATCH_EVENT)) {
		if(debug) log(" Collect data before the dispatch..."); //NOI18N
		methodName = "handleDispatchedBefore"; //NOI18N
	    }
	    else {
		if(debug) log(" Collect data after the dispatch..."); //NOI18N
		methodName = "handleDispatchedAfter"; //NOI18N
	    }
	
	    // It's no big deal if this does not succeed. All that
	    // happens is that we don't record data for when the
	    // resource that was dispatched to processes. 
	    try {
		Method method = clazz.getMethod(methodName, argtypes);
		method.invoke(filter, args);
		if(debug) log("Success\n"); //NII18N
	    }
	    catch (NoSuchMethodException mex) {
		if(debug) log("That didn't work - no such method"); //NOI18N
		if(debug) mex.printStackTrace();
	    } catch (SecurityException sex) {
		if(debug) log("That didn't work - security exception"); //NOI18N
		if(debug) sex.printStackTrace();
	    }
	    catch(Throwable t) {
		if(debug) log("That didn't work"); //NOI18N
		if(debug) t.printStackTrace();
	    }
	}
	//if(debug) log("instanceEvent(): end"); //NOI18N
    }
    
    
    private void log(String s) {
	System.out.println("ServletListener::" + s); //NOI18N
    }
    
} // ServletListener