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/*******************************************************************************

 * Copyright (c) 2005, 2010 IBM Corporation and others.

 * All rights reserved. This program and the accompanying materials

 * are made available under the terms of the Eclipse Public License v1.0

 * which accompanies this distribution, and is available at

 * http://www.eclipse.org/legal/epl-v10.html

 *

 * Contributors:

 *     IBM Corporation - initial API and implementation

 *******************************************************************************/

package org.eclipse.ui.internal.navigator.wizards;

import java.util.Iterator;

import org.eclipse.core.expressions.ElementHandler;

import org.eclipse.core.expressions.EvaluationContext;

import org.eclipse.core.expressions.EvaluationResult;

import org.eclipse.core.expressions.Expression;

import org.eclipse.core.expressions.ExpressionConverter;

import org.eclipse.core.expressions.IEvaluationContext;

import org.eclipse.core.runtime.CoreException;

import org.eclipse.core.runtime.IConfigurationElement;

import org.eclipse.core.runtime.IStatus;

import org.eclipse.jface.viewers.IStructuredSelection;

import org.eclipse.ui.IPluginContribution;

import org.eclipse.ui.WorkbenchException;

import org.eclipse.ui.internal.navigator.NavigatorPlugin;

import org.eclipse.ui.internal.navigator.extensions.INavigatorContentExtPtConstants;

/**

 * <p>

 * <strong>EXPERIMENTAL</strong>. This class or interface has been added as

 * part of a work in progress. There is a guarantee neither that this API will

 * work nor that it will remain the same. Please do not use this API without

 * consulting with the Platform/UI team.

 * </p>

 * 

 * @since 3.2

 */

public class CommonWizardDescriptor implements INavigatorContentExtPtConstants, IPluginContribution {

	/** The default menu group id for commonWizards without a menuGroupId attribute. */

	public static final String DEFAULT_MENU_GROUP_ID = "all-uncategorized"; //$NON-NLS-1$

	private String id;

	private String wizardId;

	private String menuGroupId; 

	private String type;

	private Expression enablement;

	private IConfigurationElement configElement;

	/**

	 * @param aConfigElement The configuration element from the extension point. 

	 * @throws WorkbenchException

	 *             if the configuration element could not be parsed. Reasons

	 *             include:

	 *             <ul>

	 *             <li>A required attribute is missing.</li>

	 *             <li>More elements are define than is allowed.</li>

	 *             </ul>

	 */

	public CommonWizardDescriptor(IConfigurationElement aConfigElement)

			throws WorkbenchException {

		super();

		configElement = aConfigElement;

		init();

	} 

	/**

	 * @param aConfigElement The configuration element from the extension point.

	 * @param anId the identifier for visibility purposes.

	 *  

	 * @throws WorkbenchException

	 *             if the configuration element could not be parsed. Reasons

	 *             include:

	 *             <ul>

	 *             <li>A required attribute is missing.</li>

	 *             <li>More elements are define than is allowed.</li>

	 *             </ul>

	 */

	public CommonWizardDescriptor(IConfigurationElement aConfigElement, String anId)

			throws WorkbenchException {

		super();

		configElement = aConfigElement;

		id = anId;

		init();

	}

	/**

	 * Determine if this content extension is enabled for the given selection.

	 * The content extension is enabled for the selection if and only if it is

	 * enabled for each element in the selection.

	 * 

	 * @param aStructuredSelection

	 *            The selection from the viewer

	 * @return True if and only if the extension is enabled for each element in

	 *         the selection.

	 */

	public boolean isEnabledFor(IStructuredSelection aStructuredSelection) {

		if (enablement == null) {

			return false;

		}

		IEvaluationContext context = null;

		IEvaluationContext parentContext = NavigatorPlugin.getApplicationContext();

		Iterator elements = aStructuredSelection.iterator();

		while (elements.hasNext()) {

			context = new EvaluationContext(parentContext, elements.next());

			context.setAllowPluginActivation(true);

			if (NavigatorPlugin.safeEvaluate(enablement, context) == EvaluationResult.FALSE) {

				return false;

			}

		}

		return true;

	}

	/**

	 * Determine if this content extension is enabled for the given element.

	 * 

	 * @param anElement

	 *            The element that should be used for the evaluation.

	 * @return True if and only if the extension is enabled for the element.

	 */

	public boolean isEnabledFor(Object anElement) {

		if (enablement == null) {

			return false;

		}

		IEvaluationContext context = NavigatorPlugin.getEvalContext(anElement);

		return (NavigatorPlugin.safeEvaluate(enablement, context) == EvaluationResult.TRUE);

	}

	void init() throws WorkbenchException { 

		wizardId = configElement.getAttribute(ATT_WIZARD_ID);

		type = configElement.getAttribute(ATT_TYPE);

		menuGroupId = configElement.getAttribute(ATT_MENU_GROUP_ID);

		if(menuGroupId == null) {

			menuGroupId = DEFAULT_MENU_GROUP_ID;

		}

		/* 

		 * The id defaults to the id of the enclosing navigatorContent extension, if any

		 * If not enclosed, this can be null initially, so it will default to the 

		 * value of the associatedExtensionId

		 *  

		 * Code elsewhere anticipates that this attribute may be null, so there is 

		 * no need to set it to a default non-null value. Indeed, this will cause

		 * incorrect behavior. 

		 * */

		if(id == null) {

			id = configElement.getAttribute(ATT_ASSOCIATED_EXTENSION_ID);

		}

		if (wizardId == null || wizardId.length() == 0) {

			throw new WorkbenchException("Missing attribute: " + //$NON-NLS-1$

					ATT_WIZARD_ID + " in common wizard extension: " + //$NON-NLS-1$

					configElement.getDeclaringExtension().getNamespaceIdentifier());

		}

		if (type == null || type.length() == 0) {

			throw new WorkbenchException("Missing attribute: " + //$NON-NLS-1$

					ATT_TYPE + " in common wizard extension: " + //$NON-NLS-1$

					configElement.getDeclaringExtension().getNamespaceIdentifier());

		}

		IConfigurationElement[] children = configElement

				.getChildren(TAG_ENABLEMENT);

		if (children.length == 1) {

			try {

				enablement = ElementHandler.getDefault().create(

						ExpressionConverter.getDefault(), children[0]);

			} catch (CoreException e) {

				NavigatorPlugin.log(IStatus.ERROR, 0, e.getMessage(), e);

			}

		} else if (children.length > 1) {

			throw new WorkbenchException("More than one element: " + //$NON-NLS-1$

					TAG_ENABLEMENT + " in common wizard extension: " + //$NON-NLS-1$

					configElement.getDeclaringExtension().getUniqueIdentifier());

		} 

	}

	/**

	 * 

	 * @return Returns the common wizard wizardId

	 */

	public String getWizardId() {

		return wizardId;

	}

	/**

	 * @return Returns the type.

	 */

	public String getType() {

		return type;

	}

	/**

	 * @return the declaring namespace.

	 */

	public String getNamespace() {

		return configElement.getDeclaringExtension().getNamespaceIdentifier(); 

	}

	/**

	 * 

	 * @return The identifier of the wizard descriptor for visiblity purposes (or null) if none.

	 */

	public String getId() {

		return id;

	}

	/**

	 * 

	 * @return A developer-defined logical group that this wizard menu option and 

	 * 	others like it should be rendered in a localized manner.

	 */

	public String getMenuGroupId() {

		return menuGroupId;

	}

	public String toString() {

		return "CommonWizardDescriptor["+getId()+", wizardId="+getWizardId()+"]"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$

	}

	/* (non-Javadoc)

	 * @see org.eclipse.ui.IPluginContribution#getLocalId()

	 */

	public String getLocalId() {

		return getWizardId();

	}

	/* (non-Javadoc)

	 * @see org.eclipse.ui.IPluginContribution#getPluginId()

	 */

	public String getPluginId() {

        return (configElement != null) ? configElement.getNamespaceIdentifier() : null;

	}

}