/*******************************************************************************
 * Copyright (c) 2000, 2017 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
 *
 *******************************************************************************/
package org.eclipse.dltk.internal.ui.typehierarchy;

import org.eclipse.dltk.core.IModelElement;
import org.eclipse.dltk.internal.ui.scriptview.SelectionTransferDropAdapter;
import org.eclipse.dltk.internal.ui.util.SelectionUtil;
import org.eclipse.jface.viewers.AbstractTreeViewer;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DropTargetEvent;

public class TypeHierarchyTransferDropAdapter extends SelectionTransferDropAdapter {

	private static final int OPERATION = DND.DROP_LINK;
	private TypeHierarchyViewPart fTypeHierarchyViewPart;

	public TypeHierarchyTransferDropAdapter(TypeHierarchyViewPart viewPart, AbstractTreeViewer viewer) {
		super(viewer);
//		setFullWidthMatchesItem(false);
		fTypeHierarchyViewPart= viewPart;
	}

	public void validateDrop(Object target, DropTargetEvent event, int operation) {
		event.detail= DND.DROP_NONE;
		initializeSelection();
		if (target != null){
//			super.validateDrop(target, event, operation);
			return;
		}
		if (getInputElement(getSelection()) != null)
			event.detail= TypeHierarchyTransferDropAdapter.OPERATION;
	}

	@Override
	public boolean isEnabled(DropTargetEvent event) {
		return true;
	}

	public void drop(Object target, DropTargetEvent event) {
		if (target != null || event.detail != TypeHierarchyTransferDropAdapter.OPERATION){
			super.performDrop(event);
			return;
		}
		IModelElement input= getInputElement(getSelection());
		fTypeHierarchyViewPart.setInputElement(input);
	}

	private static IModelElement getInputElement(ISelection selection) {
		Object single= SelectionUtil.getSingleElement(selection);
		if (single == null)
			return null;
		IModelElement[] candidates= OpenTypeHierarchyUtil.getCandidates(single);
		if (candidates != null && candidates.length > 0)
			return candidates[0];
		return null;
	}
}