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Wicket is a Java web application framework that takes simplicity, separation of concerns and ease of development to a whole new level. Wicket pages can be mocked up, previewed and later revised using standard WYSIWYG HTML design tools. Dynamic content processing and form handling is all handled in Java code using a first-class component model backed by POJO data beans that can easily be persisted using your favorite technology.
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/*
 * 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.wicket;

import java.util.List;

import org.apache.wicket.behavior.Behavior;
import org.apache.wicket.event.Broadcast;
import org.apache.wicket.event.IEventSink;
import org.apache.wicket.event.IEventSource;
import org.apache.wicket.request.cycle.RequestCycle;
import org.apache.wicket.util.lang.Args;
import org.apache.wicket.util.visit.IVisit;
import org.apache.wicket.util.visit.IVisitor;
import org.apache.wicket.util.visit.Visits;

/**
 * Implements event {@link Broadcast}ing
 * 
 * @author Igor Vaynberg (ivaynberg)
 */
final class ComponentEventSender implements IEventSource
{
	private final Component source;
	private final IEventDispatcher dispatcher;

	/**
	 * Constructor
	 * 
	 * @param source
	 *            component that originated the event
	 * @param dispatcher
	 */
	public ComponentEventSender(Component source, IEventDispatcher dispatcher)
	{
		Args.notNull(source, "source");
		Args.notNull(dispatcher, "dispatcher");
		this.source = source;
		this.dispatcher = dispatcher;
	}

	/** {@inheritDoc} */
	@Override
	public  void send(IEventSink sink, Broadcast type, T payload)
	{
		ComponentEvent event = new ComponentEvent(sink, source, type, payload);
		Args.notNull(type, "type");
		switch (type)
		{
			case BUBBLE :
				bubble(event);
				break;
			case BREADTH :
				breadth(event);
				break;
			case DEPTH :
				depth(event);
				break;
			case EXACT :
				exact(event);
				break;
		}
	}

	/**
	 * Exact broadcast
	 *
	 * Broadcasts the event only to the sink. In case the sink is a Component
	 * then all its behaviors are notified as well.
	 *
	 * @param event
	 *          The event with the payload
	 */
	private void exact(ComponentEvent event)
	{
		IEventSink sink = event.getSink();

		if (sink instanceof Component)
		{
			dispatchToComponent(dispatcher, (Component) sink, event);
		}
		else
		{
			dispatcher.dispatchEvent(sink, event, null);
		}
	}

	/**
	 * Breadth broadcast
	 * 
	 * @param event
	 */
	private void breadth(final ComponentEvent event)
	{
		IEventSink sink = event.getSink();

		boolean targetsApplication = sink instanceof Application;
		boolean targetsSession = targetsApplication || sink instanceof Session;
		boolean targetsCycle = targetsSession || sink instanceof RequestCycle;
		boolean targetsComponent = sink instanceof Component;

		if (!targetsComponent && !targetsCycle)
		{
			dispatcher.dispatchEvent(sink, event, null);
			return;
		}

		if (targetsApplication)
		{
			dispatcher.dispatchEvent(source.getApplication(), event, null);
		}
		if (event.isStop())
		{
			return;
		}
		if (targetsSession)
		{
			dispatcher.dispatchEvent(source.getSession(), event, null);
		}
		if (event.isStop())
		{
			return;
		}
		if (targetsCycle)
		{
			dispatcher.dispatchEvent(source.getRequestCycle(), event, null);
		}
		if (event.isStop())
		{
			return;
		}

		Component cursor = targetsCycle ? source.getPage() : (Component)sink;

		dispatchToComponent(dispatcher, cursor, event);

		if (event.isStop())
		{
			return;
		}

		event.resetShallow(); // reset shallow flag

		if (cursor instanceof MarkupContainer)
		{
			((MarkupContainer)cursor).visitChildren(new ComponentEventVisitor(event, dispatcher));
		}
	}

	/**
	 * Depth broadcast
	 * 
	 * @param event
	 *            event
	 */
	private void depth(final ComponentEvent event)
	{
		IEventSink sink = event.getSink();

		boolean targetsApplication = sink instanceof Application;
		boolean targetsSession = targetsApplication || sink instanceof Session;
		boolean targetsCycle = targetsSession || sink instanceof RequestCycle;
		boolean targetsComponent = sink instanceof Component;

		if (!targetsComponent && !targetsCycle)
		{
			dispatcher.dispatchEvent(sink, event, null);
			return;
		}

		Component cursor = (targetsCycle) ? source.getPage() : (Component)sink;

		if (cursor instanceof MarkupContainer)
		{
			Visits.visitPostOrder(cursor, new ComponentEventVisitor(event, dispatcher));
		}
		else
		{
			dispatchToComponent(dispatcher, cursor, event);
		}
		if (event.isStop())
		{
			return;
		}
		if (targetsCycle)
		{
			dispatcher.dispatchEvent(source.getRequestCycle(), event, null);
		}
		if (event.isStop())
		{
			return;
		}
		if (targetsSession)
		{
			dispatcher.dispatchEvent(source.getSession(), event, null);
		}
		if (event.isStop())
		{
			return;
		}
		if (targetsApplication)
		{
			dispatcher.dispatchEvent(source.getApplication(), event, null);
		}
	}

	/**
	 * Bubbles the event
	 * 
	 * @param event
	 *            event
	 */
	private void bubble(ComponentEvent event)
	{
		IEventSink sink = event.getSink();

		boolean targetsComponent = sink instanceof Component;
		boolean targetsCycle = targetsComponent || sink instanceof RequestCycle;
		boolean targetsSession = targetsCycle || sink instanceof Session;
		boolean targetsApplication = targetsSession || sink instanceof Application;

		if (!targetsApplication && !targetsComponent)
		{
			dispatcher.dispatchEvent(sink, event, null);
			return;
		}

		if (targetsComponent)
		{
			Component cursor = (Component)sink;
			dispatchToComponent(dispatcher, cursor, event);
			if (event.isStop())
			{
				return;
			}
			cursor.visitParents(MarkupContainer.class, new ComponentEventVisitor(event, dispatcher));
		}

		if (event.isStop())
		{
			return;
		}
		if (targetsCycle)
		{
			dispatcher.dispatchEvent(source.getRequestCycle(), event, null);
		}
		if (event.isStop())
		{
			return;
		}
		if (targetsSession)
		{
			dispatcher.dispatchEvent(source.getSession(), event, null);
		}
		if (event.isStop())
		{
			return;
		}
		if (targetsApplication)
		{
			dispatcher.dispatchEvent(source.getApplication(), event, null);
		}
	}

	private static void dispatchToComponent(IEventDispatcher dispatcher, Component object,
		ComponentEvent e)
	{
		dispatcher.dispatchEvent(object, e, null);

		if (e.isStop())
		{
			return;
		}

		List behaviors = object.getBehaviors();
		for (Behavior behavior : behaviors)
		{
			dispatcher.dispatchEvent(behavior, e, object);
			if (e.isStop())
			{
				break;
			}
		}
	}


	/**
	 * Visitor used to broadcast events to components
	 * 
	 * @author igor
	 */
	private static class ComponentEventVisitor implements IVisitor
	{
		private final ComponentEvent e;
		private final IEventDispatcher dispatcher;

		/**
		 * Constructor
		 * 
		 * @param event
		 *            event to send
		 * @param dispatcher
		 *            event dispatcher
		 */
		private ComponentEventVisitor(ComponentEvent event, IEventDispatcher dispatcher)
		{
			e = event;
			this.dispatcher = dispatcher;
		}

		/** {@inheritDoc} */
		@Override
		public void component(T object, IVisit visit)
		{
			dispatchToComponent(dispatcher, object, e);

			if (e.isStop())
			{
				visit.stop();
			}

			if (e.isShallow())
			{
				visit.dontGoDeeper();
			}

			e.resetShallow(); // reset shallow bit
		}
	}

}