/*
 * 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.
 */
/*
 * $Id$
 */

package org.apache.xalan.xsltc.trax;

import java.io.IOException;

import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.apache.xml.serializer.SerializationHandler;
import org.xml.sax.ContentHandler;
import org.xml.sax.DTDHandler;
import org.xml.sax.EntityResolver;
import org.xml.sax.ErrorHandler;
import org.xml.sax.InputSource;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.SAXNotRecognizedException;
import org.xml.sax.SAXNotSupportedException;
import org.xml.sax.XMLReader;
import org.apache.xml.serializer.NamespaceMappings;

/**
 * @author Santiago Pericas-Geertsen
 */
public class DOM2TO implements XMLReader, Locator {

    private final static String EMPTYSTRING = "";
    private static final String XMLNS_PREFIX = "xmlns";

    /**
     * A reference to the DOM to be traversed.
     */
    private Node _dom;

    /**
     * A reference to the output handler receiving the events.
     */
    private SerializationHandler _handler;

    public DOM2TO(Node root, SerializationHandler handler) {
	_dom = root;
	_handler = handler;
    }

    public ContentHandler getContentHandler() { 
	return null;
    }

    public void setContentHandler(ContentHandler handler) {
	// Empty
    }

    public void parse(InputSource unused) throws IOException, SAXException {
        parse(_dom);
    }

    public void parse() throws IOException, SAXException {
	if (_dom != null) {
	    boolean isIncomplete = 
		(_dom.getNodeType() != org.w3c.dom.Node.DOCUMENT_NODE);

	    if (isIncomplete) {
		_handler.startDocument();
		parse(_dom);
		_handler.endDocument();
	    }
	    else {
		parse(_dom);
	    }
	}
    }

    /**
     * Traverse the DOM and generate TO events for a handler. Notice that 
     * we need to handle implicit namespace declarations too.
     */
    private void parse(Node node) 
	throws IOException, SAXException 
    {
 	if (node == null) return;

        switch (node.getNodeType()) {
	case Node.ATTRIBUTE_NODE:         // handled by ELEMENT_NODE
	case Node.DOCUMENT_TYPE_NODE :
	case Node.ENTITY_NODE :
	case Node.ENTITY_REFERENCE_NODE:
	case Node.NOTATION_NODE :
	    // These node types are ignored!!!
	    break;
	case Node.CDATA_SECTION_NODE:
	    _handler.startCDATA();
	    _handler.characters(node.getNodeValue());
	    _handler.endCDATA();
	    break;

	case Node.COMMENT_NODE:           // should be handled!!!
	    _handler.comment(node.getNodeValue());
	    break;

	case Node.DOCUMENT_NODE:
	    _handler.startDocument();
	    Node next = node.getFirstChild();
	    while (next != null) {
		parse(next);
		next = next.getNextSibling();
	    }
	    _handler.endDocument();
	    break;

	case Node.DOCUMENT_FRAGMENT_NODE:
	    next = node.getFirstChild();
	    while (next != null) {
		parse(next);
		next = next.getNextSibling();
	    }
	    break;

	case Node.ELEMENT_NODE:
	    // Generate SAX event to start element
	    final String qname = node.getNodeName();
	    _handler.startElement(null, null, qname);

            int colon;
	    String prefix;
	    final NamedNodeMap map = node.getAttributes();
	    final int length = map.getLength();

	    // Process all namespace attributes first
	    for (int i = 0; i < length; i++) {
		final Node attr = map.item(i);
		final String qnameAttr = attr.getNodeName();

                // Is this a namespace declaration?
		if (qnameAttr.startsWith(XMLNS_PREFIX)) {
		    final String uriAttr = attr.getNodeValue();
		    colon = qnameAttr.lastIndexOf(':');
		    prefix = (colon > 0) ? qnameAttr.substring(colon + 1) 
			                 : EMPTYSTRING;
		    _handler.namespaceAfterStartElement(prefix, uriAttr);
		}
	    }
            
	    // Process all non-namespace attributes next
            NamespaceMappings nm = new NamespaceMappings();
	    for (int i = 0; i < length; i++) {
		final Node attr = map.item(i);
		final String qnameAttr = attr.getNodeName();

                // Is this a regular attribute?
		if (!qnameAttr.startsWith(XMLNS_PREFIX)) {
		    final String uriAttr = attr.getNamespaceURI();
		    // Uri may be implicitly declared
		    if (uriAttr != null && !uriAttr.equals(EMPTYSTRING) ) {	
			colon = qnameAttr.lastIndexOf(':');
                           
                        // Fix for bug 26319
                        // For attributes not given an prefix explictly
                        // but having a namespace uri we need
                        // to explicitly generate the prefix
                        String newPrefix = nm.lookupPrefix(uriAttr);
                        if (newPrefix == null) 
                            newPrefix = nm.generateNextPrefix();
			prefix = (colon > 0) ? qnameAttr.substring(0, colon) 
			    : newPrefix;
			_handler.namespaceAfterStartElement(prefix, uriAttr);
		        _handler.addAttribute((prefix + ":" + qnameAttr),
                            attr.getNodeValue());
		    } else {
                         _handler.addAttribute(qnameAttr, attr.getNodeValue());
                    }
                }
	    }

	    // Now element namespace and children
	    final String uri = node.getNamespaceURI();
            final String localName = node.getLocalName();

	    // Uri may be implicitly declared
	    if (uri != null) {	
		colon = qname.lastIndexOf(':');
		prefix = (colon > 0) ? qname.substring(0, colon) : EMPTYSTRING;
		_handler.namespaceAfterStartElement(prefix, uri);
	    }else {
                  // Fix for bug 26319
                  // If an element foo is created using
                  // createElementNS(null,locName)
                  // then the  element should be serialized
                  // <foo xmlns=" "/> 
                  if (uri == null  && localName != null) {
 		     prefix = EMPTYSTRING;
		     _handler.namespaceAfterStartElement(prefix, EMPTYSTRING);
                 }
            }

	    // Traverse all child nodes of the element (if any)
	    next = node.getFirstChild();
	    while (next != null) {
		parse(next);
		next = next.getNextSibling();
	    }

	    // Generate SAX event to close element
	    _handler.endElement(qname);
	    break;

	case Node.PROCESSING_INSTRUCTION_NODE:
	    _handler.processingInstruction(node.getNodeName(),
					   node.getNodeValue());
	    break;

	case Node.TEXT_NODE:
	    _handler.characters(node.getNodeValue());
	    break;
	}
    }

    /**
     * This class is only used internally so this method should never 
     * be called.
     */
    public DTDHandler getDTDHandler() { 
	return null;
    }

    /**
     * This class is only used internally so this method should never 
     * be called.
     */
    public ErrorHandler getErrorHandler() {
	return null;
    }

    /**
     * This class is only used internally so this method should never 
     * be called.
     */
    public boolean getFeature(String name) throws SAXNotRecognizedException,
	SAXNotSupportedException
    {
	return false;
    }

    /**
     * This class is only used internally so this method should never 
     * be called.
     */
    public void setFeature(String name, boolean value) throws 
	SAXNotRecognizedException, SAXNotSupportedException 
    {
    }

    /**
     * This class is only used internally so this method should never 
     * be called.
     */
    public void parse(String sysId) throws IOException, SAXException {
	throw new IOException("This method is not yet implemented.");
    }

    /**
     * This class is only used internally so this method should never 
     * be called.
     */
    public void setDTDHandler(DTDHandler handler) throws NullPointerException {
    }

    /**
     * This class is only used internally so this method should never 
     * be called.
     */
    public void setEntityResolver(EntityResolver resolver) throws 
	NullPointerException 
    {
    }

    /**
     * This class is only used internally so this method should never 
     * be called.
     */
    public EntityResolver getEntityResolver() {
	return null;
    }

    /**
     * This class is only used internally so this method should never 
     * be called.
     */
    public void setErrorHandler(ErrorHandler handler) throws 
	NullPointerException
    {
    }

    /**
     * This class is only used internally so this method should never 
     * be called.
     */
    public void setProperty(String name, Object value) throws
	SAXNotRecognizedException, SAXNotSupportedException {
    }

    /**
     * This class is only used internally so this method should never 
     * be called.
     */
    public Object getProperty(String name) throws SAXNotRecognizedException,
	SAXNotSupportedException
    {
	return null;
    }

    /**
     * This class is only used internally so this method should never 
     * be called.
     */
    public int getColumnNumber() { 
	return 0; 
    }
    
    /**
     * This class is only used internally so this method should never 
     * be called.
     */
    public int getLineNumber() { 
	return 0; 
    }

    /**
     * This class is only used internally so this method should never 
     * be called.
     */
    public String getPublicId() { 
	return null; 
    }

    /**
     * This class is only used internally so this method should never 
     * be called.
     */
    public String getSystemId() { 
	return null; 
    }

    // Debugging 
    private String getNodeTypeFromCode(short code) {
	String retval = null;
	switch (code) {
	case Node.ATTRIBUTE_NODE : 
	    retval = "ATTRIBUTE_NODE"; break; 
	case Node.CDATA_SECTION_NODE :
	    retval = "CDATA_SECTION_NODE"; break; 
	case Node.COMMENT_NODE :
	    retval = "COMMENT_NODE"; break; 
	case Node.DOCUMENT_FRAGMENT_NODE :
	    retval = "DOCUMENT_FRAGMENT_NODE"; break; 
	case Node.DOCUMENT_NODE :
	    retval = "DOCUMENT_NODE"; break; 
	case Node.DOCUMENT_TYPE_NODE :
	    retval = "DOCUMENT_TYPE_NODE"; break; 
	case Node.ELEMENT_NODE :
	    retval = "ELEMENT_NODE"; break; 
	case Node.ENTITY_NODE :
	    retval = "ENTITY_NODE"; break; 
	case Node.ENTITY_REFERENCE_NODE :
	    retval = "ENTITY_REFERENCE_NODE"; break; 
	case Node.NOTATION_NODE :
	    retval = "NOTATION_NODE"; break; 
	case Node.PROCESSING_INSTRUCTION_NODE :
	    retval = "PROCESSING_INSTRUCTION_NODE"; break; 
	case Node.TEXT_NODE:
	    retval = "TEXT_NODE"; break; 
        }
	return retval;
    }
}