/**********************************************
    * Copyright (C) 2011 Lukas Laag
    * This file is part of svgreal.
    * 
    * svgreal is free software: you can redistribute it and/or modify
    * it under the terms of the GNU General Public License as published by
    * the Free Software Foundation, either version 3 of the License, or
    * (at your option) any later version.
    * 
   * svgreal is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   * 
   * You should have received a copy of the GNU General Public License
   * along with svgreal.  If not, see http://www.gnu.org/licenses/
   **********************************************/
  package org.vectomatic.svg.edit.client.command.dnd;
  
  import java.util.List;
  
  import org.vectomatic.dom.svg.utils.SVGConstants;
  import org.vectomatic.svg.edit.client.engine.SVGModel;
  import org.vectomatic.svg.edit.client.model.svg.SVGElementModel;
  import org.vectomatic.svg.edit.client.model.svg.SVGViewBoxElementModel;
  
  import com.extjs.gxt.ui.client.event.DNDEvent;
  
  /**
   * Base class for drag and drop handlers
   * @author laaglu
   */
  public abstract class DndHandlerBase implements IDndHandler {
  	@Override
  	public boolean isValidSource(DNDEvent event, List<SVGElementModel> sourceElements) {
  		// Forbid dragging the tree root or the viewbox of a model
  		SVGModel model = sourceElements.get(0).getOwner();
  		SVGElementModel root = model.getRoot();
  		SVGViewBoxElementModel viewBox = model.getViewBox();
  		for (SVGElementModel sourceElement : sourceElements) {
  			if (sourceElement == root || sourceElement == viewBox) {
  				return false;
  			}
  		}
  		return true;
  	}
  	
  	public static String getSourceElementNames(List<SVGElementModel> sourceElements) {
  		int size = sourceElements.size();
  		if (size == 1) {
  			return sourceElements.get(0).<String>get(SVGConstants.SVG_TITLE_TAG);
  		}
  		StringBuilder builder = new StringBuilder();
  		for (int i = 0; i < size; i++) {
  			if (i > 0) {
  				builder.append(";");
  			}
  			builder.append(sourceElements.get(i).<String>get(SVGConstants.SVG_TITLE_TAG));
  		}
  		return builder.toString();
  	}
  
  	
  	@Override
  	public boolean isValidTarget(List<SVGElementModel> sourceElements, SVGElementModel target) {
  		if (target == null) {
  			return false;
  		}
  		// The viewBox is not a valid drop target
  		if (target instanceof SVGViewBoxElementModel) {
  			return false;
  		}
  		// An element cannot be dropped onto itself or one of its descendants
  		for (SVGElementModel sourceElement : sourceElements) {
  			if (sourceElement.isAncestorOf(target)) {
  				return false;
  			}
  		}
  		return true;
  	}
  
  	@Override
  	public int getKeyCode() {
  		return -1;
  	}
  }