/*******************************************************************************
 * Copyright (c) 2011, 2012 Ericsson AB 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
 * 
 * Description:
 * 
 * This class implements a property testers that looks to see if the element can be 
 * transitioned to its previous state
 * 
 * Contributors:
 *   Sebastien Dubois - Created for Mylyn Review R4E project
 *   
 ******************************************************************************/

package org.eclipse.mylyn.reviews.r4e.ui.internal.commands.testers;

import java.util.List;

import org.eclipse.core.expressions.PropertyTester;
import org.eclipse.mylyn.reviews.r4e.core.model.R4EReviewPhase;
import org.eclipse.mylyn.reviews.r4e.core.model.R4EReviewState;
import org.eclipse.mylyn.reviews.r4e.ui.internal.model.IR4EUIModelElement;
import org.eclipse.mylyn.reviews.r4e.ui.internal.model.R4EUIAnomalyExtended;
import org.eclipse.mylyn.reviews.r4e.ui.internal.model.R4EUIModelController;
import org.eclipse.mylyn.reviews.r4e.ui.internal.model.R4EUIReviewBasic;
import org.eclipse.mylyn.reviews.r4e.ui.internal.model.R4EUIReviewExtended;
import org.eclipse.mylyn.reviews.r4e.ui.internal.utils.UIUtils;

/**
 * @author Sebastien Dubois
 * @version $Revision: 1.0 $
 */
public class PreviousStatePropertyTester extends PropertyTester {

	/**
	 * Executes the property test determined by the parameter <code>property</code>.
	 * 
	 * @param aReceiver
	 *            the receiver of the property test
	 * @param aProperty
	 *            the property to test
	 * @param aArgs
	 *            additional arguments to evaluate the property. If no arguments are specified in the <code>test</code>
	 *            expression an array of length 0 is passed
	 * @param aExpectedValue
	 *            the expected value of the property. The value is either of type <code>java.lang.String</code> or a
	 *            boxed base type. If no value was specified in the <code>test</code> expressions then <code>null</code>
	 *            is passed
	 * @return returns <code>true</code> if the property is equal to the expected value; otherwise <code>false</code> is
	 *         returned
	 * @see org.eclipse.core.expressions.IPropertyTester#test(Object receiver, String property, Object[] args, Object
	 *      expectedValue)
	 */
	//NOTE:  This method is overriden, but we do not use the parameters
	public boolean test(Object aReceiver, String aProperty, Object[] aArgs, Object aExpectedValue) {

		if (null != R4EUIModelController.getActiveReview() && !R4EUIModelController.getActiveReview().isReadOnly()) {
			final List<IR4EUIModelElement> selectedElements = UIUtils.getCommandUIElements();
			if (null != selectedElements && selectedElements.size() > 0) {
				return testElement(selectedElements.get(0));
			}
		}
		return false;
	}

	/**
	 * Method testElement
	 * 
	 * @param aElement
	 *            - IR4EUIModelElement
	 * @return boolean
	 */
	private boolean testElement(IR4EUIModelElement aElement) {
		if (aElement.isEnabled()) {
			if (aElement instanceof R4EUIReviewExtended) {
				if (((R4EUIReviewExtended) aElement).isOpen()
						&& null != ((R4EUIReviewExtended) aElement).getPreviousPhase()) {
					return true;
				}
			} else if (aElement instanceof R4EUIReviewBasic) {
				if (((R4EUIReviewBasic) aElement).isOpen()
						&& ((R4EReviewState) ((R4EUIReviewBasic) aElement).getReview().getState()).getState().equals(
								R4EReviewPhase.COMPLETED)) {
					return true;
				}
			} else if (aElement instanceof R4EUIAnomalyExtended) {
				if (!((R4EReviewState) R4EUIModelController.getActiveReview().getReview().getState()).getState()
						.equals(R4EReviewPhase.COMPLETED)
						&& null != ((R4EUIAnomalyExtended) aElement).getPreviousState()) {
					return true;
				}
			}
		}
		return false;
	}
}