/*

   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

 */
package org.apache.batik.svggen;

import java.util.List;
import java.util.ArrayList;

import org.w3c.dom.Attr;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/**
 * This utility class converts a standard SVG document that uses
 * attribute into one that uses the CSS style attribute instead.
 *
 * @author <a href="mailto:vincent.hardy@eng.sun.com">Vincent Hardy</a>
 * @version $Id$
 */
public class SVGCSSStyler implements SVGSyntax{

    private static final char CSS_PROPERTY_VALUE_SEPARATOR = ':';
    private static final char CSS_RULE_SEPARATOR = ';';
    private static final char SPACE = ' ';

    /**
     * Invoking this method removes all the styling attributes
     * (such as 'fill' or 'fill-opacity') from the input element
     * and its descendant and replaces them with their CSS2
     * property counterparts.
     *
     * @param node SVG Node to be converted to use style
     */
    public static void style(Node node){
        NamedNodeMap attributes = node.getAttributes();
        if (attributes != null){
            // Has to be an Element, as it has attributes
            // According to spec.
            Element element = (Element)node;
            StringBuffer styleAttrBuffer = new StringBuffer();
            int nAttr = attributes.getLength();
            List toBeRemoved = new ArrayList();
            for(int i=0; i<nAttr; i++){
                Attr attr = (Attr)attributes.item(i);
                String attrName = attr.getName();
                if(SVGStylingAttributes.set.contains( attrName )){
                    // System.out.println("Found new style attribute");
                    styleAttrBuffer.append( attrName );
                    styleAttrBuffer.append(CSS_PROPERTY_VALUE_SEPARATOR);
                    styleAttrBuffer.append(attr.getValue());
                    styleAttrBuffer.append(CSS_RULE_SEPARATOR);
                    styleAttrBuffer.append(SPACE);
                    toBeRemoved.add( attrName );
                }
            }

            if(styleAttrBuffer.length() > 0){
                // There were some styling attributes
                // System.out.println("Setting style attribute on node: " + styleAttrBuffer.toString().trim());
                element.setAttributeNS(null,
                                       SVG_STYLE_ATTRIBUTE,
                                       styleAttrBuffer.toString().trim());

                int n = toBeRemoved.size();
                for (Object aToBeRemoved : toBeRemoved) {
                    element.removeAttribute((String) aToBeRemoved);
                }
            }
            // else
            // System.out.println("NO STYLE PROPERTIES");
        }

        // Now, process child elements
        NodeList children = node.getChildNodes();
        int nChildren = children.getLength();
        for(int i=0; i<nChildren; i++){
            Node child = children.item(i);
            style(child);
        }

    }
}
