/*****************************************************************************
 * Copyright (c) 2010-2011 CEA LIST.
 *
 *    
 * 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:
 * 
 * 		Yann Tanguy (CEA LIST) yann.tanguy@cea.fr - Initial API and implementation
 *
 *****************************************************************************/
package org.eclipse.papyrus.uml.service.types.helper;

import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.ecore.EReference;
import org.eclipse.gmf.runtime.common.core.command.ICommand;
import org.eclipse.gmf.runtime.common.core.command.IdentityCommand;
import org.eclipse.gmf.runtime.common.core.command.UnexecutableCommand;
import org.eclipse.gmf.runtime.emf.type.core.commands.CreateRelationshipCommand;
import org.eclipse.gmf.runtime.emf.type.core.requests.CreateRelationshipRequest;
import org.eclipse.gmf.runtime.emf.type.core.requests.ReorientRelationshipRequest;
import org.eclipse.papyrus.uml.service.types.command.GeneralizationReorientCommand;
import org.eclipse.uml2.uml.Classifier;
import org.eclipse.uml2.uml.Generalization;
import org.eclipse.uml2.uml.UMLPackage;

/**
 * This helper provides edit commands for UML {@link Generalization}.
 */
public class GeneralizationEditHelper extends DirectedRelationshipEditHelper {

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected EReference getSourceReference() {
		return UMLPackage.eINSTANCE.getGeneralization_Specific();
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected EReference getTargetReference() {
		return UMLPackage.eINSTANCE.getGeneralization_General();
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected boolean canCreate(EObject source, EObject target) {

		if ((source != null) && !(source instanceof Classifier)) {
			return false;
		}
		
		if ((target != null) && !(target instanceof Classifier)) {
			return false;
		}
		
		if ((source != null) && (target != null) && (source == target)) {
			return false;
		}
		
		return true;
	}
	
	/**
	 * {@inheritDoc}
	 */
	@Override
	protected ICommand getCreateRelationshipCommand(CreateRelationshipRequest req) {

		EObject source = req.getSource();
		EObject target = req.getTarget();

		boolean noSourceOrTarget = (source == null || target == null);
		boolean noSourceAndTarget = (source == null && target == null);

		if (!noSourceAndTarget && !canCreate(source, target)) {
			// Abort creation.
			return UnexecutableCommand.INSTANCE;
		}
		
		if(noSourceOrTarget && !noSourceAndTarget) {
			// The request isn't complete yet. Return the identity command so
			// that the create relationship gesture is enabled.
			return IdentityCommand.INSTANCE;
		}

		// Propose a container if none is set in request.
		EObject proposedContainer = source;
		req.setContainer(proposedContainer);
		
		return new CreateRelationshipCommand(req);
	}
	
	/**
	 * {@inheritDoc}
	 */
	@Override
	protected ICommand getReorientRelationshipCommand(ReorientRelationshipRequest req) {
		return new GeneralizationReorientCommand(req);
	}
}