/*
 * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.xml.internal.xsom.util;

import com.sun.xml.internal.xsom.XSAnnotation;
import com.sun.xml.internal.xsom.parser.AnnotationContext;
import com.sun.xml.internal.xsom.parser.AnnotationParser;
import com.sun.xml.internal.xsom.parser.AnnotationParserFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.xml.sax.ContentHandler;
import org.xml.sax.EntityResolver;
import org.xml.sax.ErrorHandler;

import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.dom.DOMResult;
import javax.xml.transform.sax.SAXTransformerFactory;
import javax.xml.transform.sax.TransformerHandler;

/**
 * {@link AnnotationParserFactory} that parses annotations into a W3C DOM.
 *
 * <p>
 * If you use this parser factory, you'll get {@link Element} that represents
 * &lt;xs:annotation> from {@link XSAnnotation#getAnnotation()}.
 *
 * <p>
 * When multiple &lt;xs:annotation>s are found for the given schema component,
 * you'll see all &lt;xs:appinfo>s and &lt;xs:documentation>s combined under
 * one &lt;xs:annotation> element.
 *
 * @author Kohsuke Kawaguchi
 */
public class DomAnnotationParserFactory implements AnnotationParserFactory {
    public AnnotationParser create() {
        return new AnnotationParserImpl();
    }

    private static final ContextClassloaderLocal<SAXTransformerFactory> stf = new ContextClassloaderLocal<SAXTransformerFactory>() {
        @Override
        protected SAXTransformerFactory initialValue() throws Exception {
            return (SAXTransformerFactory) SAXTransformerFactory.newInstance();
        }
    };

    private static class AnnotationParserImpl extends AnnotationParser {

        /**
         * Identity transformer used to parse SAX into DOM.
         */
        private final TransformerHandler transformer;
        private DOMResult result;

        AnnotationParserImpl() {
            try {
                transformer = stf.get().newTransformerHandler();
            } catch (TransformerConfigurationException e) {
                throw new Error(e); // impossible
            }
        }

        public ContentHandler getContentHandler(AnnotationContext context, String parentElementName, ErrorHandler errorHandler, EntityResolver entityResolver) {
            result = new DOMResult();
            transformer.setResult(result);
            return transformer;
        }

        public Object getResult(Object existing) {
            Document dom = (Document)result.getNode();
            Element e = dom.getDocumentElement();
            if(existing instanceof Element) {
                // merge all the children
                Element prev = (Element) existing;
                Node anchor = e.getFirstChild();
                while(prev.getFirstChild()!=null) {
                    Node move = prev.getFirstChild();
                    e.insertBefore(e.getOwnerDocument().adoptNode(move), anchor );
                }
            }
            return e;
        }
    }
}
