/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.help;

import org.eclipse.jface.util.Assert;
import org.eclipse.help.*;
import org.eclipse.ui.IViewPart;
import org.eclipse.swt.events.HelpEvent;
import org.eclipse.swt.widgets.Control;
import java.util.*;

/**
 * For determining the help context for controls in a view.
 * <p>
 * This class may be instantiated; it is not intended to be subclassed.
 * </p>
 * @deprecated nested contexts are no longer supported by the help support system
 */ 
public class ViewContextComputer implements IContextComputer {
	private IViewPart view;
	private ArrayList contextList;
	private Object context;
/**
 * Creates a new context computer for the given view and help context.
 *
 * @param viewPart the view
 * @param helpContext a single help context id (type <code>String</code>) or
 *  help context object (type <code>IContext</code>)
 */
public ViewContextComputer(IViewPart viewPart, Object helpContext) {
	Assert.isTrue(helpContext instanceof String || helpContext instanceof IContext);
	view = viewPart;
	context = helpContext;
}
/**
 * Add the contexts to the context list.
 *
 * @param object the contexts (<code>Object[]</code> or <code>IContextComputer</code>)
 * @param event the help event 
 */
private void addContexts(Object object, HelpEvent event) {
	Assert.isTrue(
		object instanceof Object[] || 
		object instanceof IContextComputer ||
		object instanceof String);
		
	if (object instanceof String) {
		contextList.add(object);
		return;
	}

	Object[] contexts;
	if (object instanceof IContextComputer) 
		// get local contexts
		contexts = ((IContextComputer)object).getLocalContexts(event);
	else
		contexts = (Object[])object;

	// copy the contexts into our list	
	for (int i = 0; i < contexts.length; i++) 
		contextList.add(contexts[i]); 
}
/**
 * Add the contexts for the given control to the context list.
 *
 * @param event the control from which to obtain the contexts
 * @param event the help event 
 */
private void addContextsForControl(Control control, HelpEvent event) {
	// See if there is are help contexts on the control
	Object object = WorkbenchHelp.getHelp(control);

	if (object == null || object == this)
		// We need to check for this in order to avoid recursion
		return;
		
	addContexts(object, event); 
}
/* (non-Javadoc)
 * Method declared on IContextComputer.
 */
public Object[] computeContexts(HelpEvent event) {
	contextList = new ArrayList();
	
	// Add the local context
	contextList.add(context);
	
	// Add the contexts for the window shell	
	addContextsForControl(view.getSite().getShell(), event); 

	// Return the contexts
	return contextList.toArray();
}
/* (non-Javadoc)
 * Method declared on IContextComputer.
 */
public Object[] getLocalContexts(HelpEvent event) {
	return new Object[] {context};
}
}