/**********************************************
    * 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.load;
  
  import org.vectomatic.dnd.DataTransferExt;
  import org.vectomatic.dom.svg.utils.SVGConstants;
  import org.vectomatic.file.File;
  import org.vectomatic.file.FileList;
  import org.vectomatic.svg.edit.client.gxt.widget.ViewportExt;
  
  import com.google.gwt.core.client.GWT;
  import com.google.gwt.event.dom.client.DragEnterEvent;
  import com.google.gwt.event.dom.client.DragEnterHandler;
  import com.google.gwt.event.dom.client.DragLeaveEvent;
  import com.google.gwt.event.dom.client.DragLeaveHandler;
  import com.google.gwt.event.dom.client.DragOverEvent;
  import com.google.gwt.event.dom.client.DragOverHandler;
  import com.google.gwt.event.dom.client.DropEvent;
  import com.google.gwt.event.dom.client.DropHandler;
  
  /**
   * Class to handler drag and drop of external files on the viewport.
   * @author laaglu
   */
  public class DndHandler implements DragEnterHandler, DragLeaveHandler, DragOverHandler, DropHandler {
  	private ViewportExt viewport;
  	public DndHandler(ViewportExt viewport) {
  		this.viewport = viewport;
  		viewport.addDragEnterHandler(this);
  		viewport.addDragLeaveHandler(this);
  		viewport.addDragOverHandler(this);
  		viewport.addDropHandler(this);
  	}
  	
  	@Override
  	public void onDragEnter(DragEnterEvent event) {
  		viewport.setStyleAttribute("background-color", SVGConstants.CSS_GAINSBORO_VALUE);
  		event.stopPropagation();
  		event.preventDefault();
  	}
  	@Override
  	public void onDragLeave(DragLeaveEvent event) {
  		viewport.setStyleAttribute("background-color", SVGConstants.CSS_BEIGE_VALUE);
  		event.stopPropagation();
  		event.preventDefault();
  	}
  	@Override
  	public void onDragOver(DragOverEvent event) {
  		// Mandatory handler, otherwise the default
  		// behavior will kick in and onDrop will never
  		// be called
  		event.stopPropagation();
  		event.preventDefault();
  	}
  	@Override
  	public void onDrop(DropEvent event) {
  		GWT.log("onDrop");
  		viewport.setStyleAttribute("background-color", SVGConstants.CSS_BEIGE_VALUE);
  		FileList files = event.getDataTransfer().<DataTransferExt>cast().getFiles();
  		for (File file : files) {
  			if ("image/svg+xml".equals(file.getType())) {
  				new FileLoadRequest(file).load();
  			}
  		}
  		event.stopPropagation();
  		event.preventDefault();
  	}
  }