/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *
 *    (C) 2016 Open Source Geospatial Foundation (OSGeo)
 *    (C) 2014-2016 Boundless Spatial
 *    
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Lesser General Public
 *    License as published by the Free Software Foundation;
 *    version 2.1 of the License.
 *
 *    This library 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
 *    Lesser General Public License for more details.
 */
package org.geotools.ysld.transform.sld;

import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import java.io.IOException;
import java.io.Writer;

import static javax.xml.stream.XMLStreamConstants.*;

/**
 * Transforms an XML/SLD stream to a Yaml/Ysld stream.
 */
public class SldTransformer {

    XMLStreamReader xml;

    SldTransformContext context;

    public SldTransformer(XMLStreamReader xml, Writer yaml) {
        this.xml = xml;
        context = new SldTransformContext(yaml);
    }

    public SldTransformContext context() {
        return context;
    }

    public void transform() throws IOException, XMLStreamException {
        context.stream().document().push(new RootHandler());

        boolean root = true;
        Integer next = xml.hasNext() ? xml.next() : null;
        while (next != null) {
            context.reset();

            SldTransformHandler h = context.handlers.peek();
            switch (next) {
            case PROCESSING_INSTRUCTION:
            case COMMENT:
            case SPACE:
                break;
            case START_DOCUMENT:
                // h.document(xml, context);
                break;
            case START_ELEMENT:
                if (root) {
                    // root element, fill in some context
                    String ver = xml.getAttributeValue(null, "version");
                    if (ver != null) {
                        context.version(ver);
                    }
                }
                root = false;
                h.element(xml, context);
                break;
            case ATTRIBUTE:
                h.attribute(xml, context);
                break;
            case CHARACTERS:
                h.characters(xml, context);
                break;
            case END_ELEMENT:
                h.endElement(xml, context);
                break;
            case END_DOCUMENT:
                // h.endDocument(xml, context);
                break;
            }

            if (context.moveToNext) {
                next = xml.hasNext() ? xml.next() : null;
            }

        }

        context.endDocument().endStream();
    }

}