org.eclipse.osbp.vaadin.emf/src/org/eclipse/osbp/vaadin/emf/actions/EmfTreeDndHandler.java

/**
 *                                                                            
 *  Copyright (c) 2011, 2016 - Loetz GmbH&Co.KG (69115 Heidelberg, Germany) 
 *                                                                            
 *  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:                                                      
 * 	   Christophe Loetz (Loetz GmbH&Co.KG) - initial implementation
 * 
 */
 package org.eclipse.osbp.vaadin.emf.actions;

import java.util.Collections;
import java.util.List;

import org.eclipse.emf.common.command.Command;
import org.eclipse.emf.common.command.CompoundCommand;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.ecore.EStructuralFeature;
import org.eclipse.emf.edit.command.AddCommand;
import org.eclipse.emf.edit.command.MoveCommand;
import org.eclipse.emf.edit.command.RemoveCommand;
import org.eclipse.emf.edit.command.SetCommand;
import org.eclipse.osbp.vaadin.emf.api.IModelingContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.vaadin.event.DataBoundTransferable;
import com.vaadin.event.dd.DragAndDropEvent;
import com.vaadin.event.dd.DropHandler;
import com.vaadin.event.dd.acceptcriteria.AcceptAll;
import com.vaadin.event.dd.acceptcriteria.AcceptCriterion;
import com.vaadin.shared.ui.dd.VerticalDropLocation;
import com.vaadin.ui.Tree;
import com.vaadin.ui.Tree.TreeTargetDetails;

@SuppressWarnings("serial")
public class EmfTreeDndHandler implements DropHandler {

	private static final Logger LOGGER = LoggerFactory
			.getLogger(EmfTreeDndHandler.class);

	private final IModelingContext modelingContext;
	private final Tree tree;

	public EmfTreeDndHandler(IModelingContext modelingContext, Tree tree) {
		super();
		this.modelingContext = modelingContext;
		this.tree = tree;
	}

	@Override
	public AcceptCriterion getAcceptCriterion() {
		return AcceptAll.get();
	}

	@SuppressWarnings("unchecked")
	@Override
	public void drop(DragAndDropEvent event) {
		DataBoundTransferable t = (DataBoundTransferable) event
				.getTransferable();

		// Make sure the drag source is the same tree
		if (t.getSourceComponent() != tree)
			return;

		TreeTargetDetails target = (TreeTargetDetails) event.getTargetDetails();

		// Get ids of the dragged item and the target item
		EObject sourceItemId = (EObject) t.getData("itemId");
		EObject targetItemId = (EObject) target.getItemIdOver();
		if (sourceItemId == null || targetItemId == null) {
			return;
		}

		// On which side of the target the item was dropped
		VerticalDropLocation location = target.getDropLocation();

		EStructuralFeature feature = sourceItemId.eContainingFeature();
		boolean isMany = feature.isMany();
		EObject targetParent = null;
		EObject sourceParent = sourceItemId.eContainer();

		int targetIndex = -1;
		// Drop right on an item -> make it a child
		if (location == VerticalDropLocation.MIDDLE) {
			if (targetItemId.eContainer() == sourceItemId.eContainer()) {
				targetParent = targetItemId.eContainer();
				if (isMany) {
					List<EObject> collection = (List<EObject>) targetParent
							.eGet(feature);
					targetIndex = collection.indexOf(targetItemId) + 1;
				}
			} else {
				targetParent = targetItemId;
				targetIndex = -1;
			}
		} else if (location == VerticalDropLocation.TOP
				|| location == VerticalDropLocation.BOTTOM) {
			if(targetItemId.eClass().getEAllStructuralFeatures().contains(feature)) {
				// we drop it in the targetItemId
				targetParent = targetItemId;
				if (isMany && targetParent.eGet(feature) instanceof List) {
					if (location == VerticalDropLocation.TOP) {
//						targetIndex = index > 0 ? index - 1 : -1;
					} else if (location == VerticalDropLocation.BOTTOM) {
						targetIndex = -1;
					}
				}
			}else{
				targetParent = targetItemId.eContainer();
				
				if (isMany && targetParent.eGet(feature) instanceof List) {
					List<EObject> collection = (List<EObject>) targetParent
							.eGet(feature);
					int index = collection.indexOf(targetItemId);
					if (location == VerticalDropLocation.TOP) {
						targetIndex = index > 0 ? index - 1 : -1;
					} else if (location == VerticalDropLocation.BOTTOM) {
						targetIndex = index;
					}
				}
			}
		}

		if (!targetParent.eClass().getEAllStructuralFeatures()
				.contains(feature)) {
			LOGGER.error("Feature " + feature.getName()
					+ " is not contained in droptarget "
					+ targetParent.eClass().getName());
			return;
		}

		boolean isMove = targetParent == sourceParent;
		if (isMany) {
			if (isMove) {
				// move if same parent
				Command command = MoveCommand.create(
						modelingContext.getEditingDomain(), targetParent,
						feature, sourceItemId, targetIndex);
				if (command.canExecute()) {
					modelingContext.getCommandStack().execute(command);
				}
			} else {
				// remove and add if new parent
				Command remove = RemoveCommand.create(
						modelingContext.getEditingDomain(),
						Collections.singletonList(sourceItemId));
				Command add = AddCommand.create(
						modelingContext.getEditingDomain(), targetParent,
						feature, sourceItemId, targetIndex);
				CompoundCommand command = new CompoundCommand();
				command.append(remove);
				command.append(add);
				if (command.canExecute()) {
					modelingContext.getCommandStack().execute(command);
				}
			}
		} else {
			Command command = SetCommand.create(
					modelingContext.getEditingDomain(), targetParent, feature,
					sourceItemId);
			if (command.canExecute()) {
				modelingContext.getCommandStack().execute(command);
			}
		}
	}
}