/**********************************************
    * 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.gxt.widget;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import org.vectomatic.dom.svg.OMSVGElement;
  import org.vectomatic.dom.svg.OMSVGMatrix;
  import org.vectomatic.dom.svg.OMSVGPoint;
  import org.vectomatic.dom.svg.OMSVGRect;
  import org.vectomatic.dom.svg.OMSVGSVGElement;
  import org.vectomatic.dom.svg.impl.SVGSVGElement;
  import org.vectomatic.dom.svg.itf.ISVGLocatable;
  import org.vectomatic.dom.svg.utils.SVGConstants;
  import org.vectomatic.svg.edit.client.AppBundle;
  import org.vectomatic.svg.edit.client.AppCss;
  import org.vectomatic.svg.edit.client.command.dnd.IDndHandler;
  import org.vectomatic.svg.edit.client.model.svg.SVGElementModel;
  
  import com.extjs.gxt.ui.client.event.DNDEvent;
  import com.extjs.gxt.ui.client.event.DragEvent;
  import com.google.gwt.core.client.GWT;
  import com.google.gwt.dom.client.DivElement;
  import com.google.gwt.dom.client.Document;
  import com.google.gwt.user.client.Element;
  
  /**
   * Class to give users visual feedback on the drag operation
   * about to be performed
   * @author laaglu
   */
  public class DNDGhost {
  	private static final String ATT_OPERATION = "operation";
  	/**
  	 * To update the DND operation
  	 */
  	private static SVGSVGElement operationElement;
  	private static DivElement messageElement;
  	private DivElement ghostElement;
  	private List<SVGElementModel> sourceElements;
  	public DNDGhost(List<SVGElementModel> sourceElements, DNDEvent event) {
  		/*
  		 * The custom ghost has the following css structure
  		 * custom ghost container div (ghost)
  		 *  source div (ghost-source)
  		 *  operation div (ghost-operation)
  		 *  message div (ghost-message)
  		 */
  		this.sourceElements = sourceElements;
  		
  		// Create the SVG miniature of the first element in the source
  		AppCss css = AppBundle.INSTANCE.css();
  		OMSVGSVGElement svg = new OMSVGSVGElement();
  		OMSVGElement svgElement = sourceElements.get(0).getElementWrapper();
  		ISVGLocatable locatable = (ISVGLocatable) svgElement;
  	    OMSVGRect bbox = getScreenBBox(svg, locatable);
  		OMSVGRect viewBox = svg.getViewBox().getBaseVal();
  		bbox.assignTo(viewBox);
  		OMSVGElement clone = (OMSVGElement) svgElement.cloneNode(true);
  		OMSVGMatrix m = locatable.getCTM();
  		if (!m.isIdentity()) {
  			StringBuilder builder = new StringBuilder();
  			builder.append(SVGConstants.TRANSFORM_MATRIX + "(");
  			builder.append(m.getDescription());
  			builder.append(")");
  			clone.setAttribute(SVGConstants.SVG_TRANSFORM_ATTRIBUTE, builder.toString());
  		} else {
  			clone.removeAttribute(SVGConstants.SVG_TRANSFORM_ATTRIBUTE);
  		}
  		
  		svg.appendChild(clone);
  		svg.setClassNameBaseVal(css.ghostSource());
  
  		// Create the operation icon
  		if (operationElement == null) {
  			operationElement = (SVGSVGElement) AppBundle.INSTANCE.dndIcons().getSvg().getElement();
  			operationElement.getClassName_().setBaseVal(css.ghostOperation());
  		}
  
  		// Create the DND message
  		if (messageElement == null) {
  			messageElement = Document.get().createDivElement();
  			messageElement.setClassName(css.ghostMessage());
 		}
 		
 		// Create the ghost
 		ghostElement = Document.get().createDivElement();
 		ghostElement.setClassName(css.ghost());
 		ghostElement.appendChild(svg.getElement());
 		ghostElement.appendChild(operationElement);
 		ghostElement.appendChild(messageElement);
 		
 		DragEvent dragEvent = event.getDragEvent();
 		dragEvent.setWidth(120);
 		dragEvent.setHeight(94);
 	}
 	
 	public void update(IDndHandler dndHandler) {
 		operationElement.setAttribute(ATT_OPERATION, dndHandler.getOperationCssAttr());
 		messageElement.setInnerText(dndHandler.getMessage(sourceElements));
 	}
 
 	public Element getElement() {
 		return (com.google.gwt.user.client.Element) ghostElement.cast();
 	}
 
 	private static OMSVGRect getScreenBBox(OMSVGSVGElement svg, ISVGLocatable locatable) {
 		OMSVGRect bbox = locatable.getBBox();
 	    OMSVGMatrix m = locatable.getCTM();
 	    List<OMSVGPoint> list = new ArrayList<OMSVGPoint>();
 	    list.add(svg.createSVGPoint(bbox.getX(), bbox.getY()).matrixTransform(m));
 	    list.add(svg.createSVGPoint(bbox.getMaxX(), bbox.getY()).matrixTransform(m));
 	    list.add(svg.createSVGPoint(bbox.getX(), bbox.getMaxY()).matrixTransform(m));
 	    list.add(svg.createSVGPoint(bbox.getMaxX(), bbox.getMaxY()).matrixTransform(m));
 	    float xmin = list.get(0).getX(), ymin = list.get(0).getY(), xmax = list.get(0).getX(), ymax = list.get(0).getY();
 		for (int i = 1, size = list.size(); i < size; i++) {
 			OMSVGPoint p = list.get(i);
 			xmin = Math.min(p.getX(), xmin);
 			ymin = Math.min(p.getY(), ymin);
 			xmax = Math.max(p.getX(), xmax);
 			ymax = Math.max(p.getY(), ymax);
 		}
 	    OMSVGRect screenBBox = svg.createSVGRect(xmin, ymin, xmax - xmin, ymax - ymin);
 		GWT.log("m="+m.getDescription());
 		GWT.log("bbox="+bbox.getDescription());
 		GWT.log("screenBBox="+screenBBox.getDescription());
 		return screenBBox;
 	}
 
 }