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/************************************************************************
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
 *
 * Copyright 2008, 2010 Oracle and/or its affiliates. All rights reserved.
 * Copyright 2010 IBM. All rights reserved.
 *
 * Use is subject to license terms.
 *
 * Licensed 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. You can also
 * obtain a copy of the License at http://odftoolkit.org/docs/license.txt
 *
 * 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.odftoolkit.odfdom.pkg;

import java.io.IOException;
import java.util.Stack;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.Text;
import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

class OdfFileSaxHandler extends DefaultHandler {

	private static final String EMPTY_STRING = "";
	// the empty XML file to which nodes will be added
	private OdfFileDom mFileDom;
	// the context node
	private Node mNode;        // a stack of sub handlers. handlers will be pushed on the stack whenever
	// they are required and must pop themselves from the stack when done
	private Stack mHandlerStack = new Stack();
	private StringBuilder mCharsForTextNode = new StringBuilder();

	OdfFileSaxHandler(Node rootNode) {
		if (rootNode instanceof OdfFileDom) {
			mFileDom = (OdfFileDom) rootNode;
		} else {
			mFileDom = (OdfFileDom) rootNode.getOwnerDocument();
		}
		mNode = rootNode;
	}

	@Override
	public void startDocument() throws SAXException {
	}

	@Override
	public void endDocument() throws SAXException {
	}

	@Override
	public void endElement(String uri, String localName, String qName) throws SAXException {
		flushTextNode();
		// pop to the parent node
		mNode = mNode.getParentNode();
	}

	@Override
	public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
		flushTextNode();
		// if there is a specilized handler on the stack, dispatch the event
		Element element = null;
		if (uri.equals(EMPTY_STRING) || qName.equals(EMPTY_STRING)) {
			element = mFileDom.createElement(localName);
		} else {
			element = mFileDom.createElementNS(uri, qName);
		}
		String attrQname = null;
		String attrURL = null;
		OdfAttribute attr = null;
		for (int i = 0; i < attributes.getLength(); i++) {
			attrURL = attributes.getURI(i);
			attrQname = attributes.getQName(i);
			// if no namespace exists
			if (attrURL.equals(EMPTY_STRING) || attrQname.equals(EMPTY_STRING)) {
				// create attribute without prefix
				attr = mFileDom.createAttribute(attributes.getLocalName(i));
			} else {
				if (attrQname.startsWith("xmlns:")) {
					// in case of xmlns prefix we have to create a new OdfNamespace
					OdfNamespace namespace = mFileDom.setNamespace(attributes.getLocalName(i), attributes.getValue(i));
					// if the file Dom is already associated to parsed XML add the new namespace to the root element
					Element root = mFileDom.getRootElement();
					if (root == null) {
						root = element;
					}
					root.setAttributeNS("http://www.w3.org/2000/xmlns/", "xmlns:" + namespace.getPrefix(), namespace.getUri());
				}
				// create all attributes, even namespace attributes
				attr = mFileDom.createAttributeNS(attrURL, attrQname);
			}

			// namespace attributes will not be created and return null
			if (attr != null) {
				element.setAttributeNodeNS(attr);
				// don't exit because of invalid attribute values
				try {
					// set Value in the attribute to allow validation in the attribute
					attr.setValue(attributes.getValue(i));
				} // if we detect an attribute with invalid value: remove attribute node
				catch (IllegalArgumentException e) {
					element.removeAttributeNode(attr);
				}
			}
		}
		// add the new element as a child of the current context node
		mNode.appendChild(element);
		// push the new element as the context node...
		mNode = element;
	}

	/**
	 * http://xerces.apache.org/xerces2-j/faq-sax.html#faq-2 :
	 * SAX may deliver contiguous text as multiple calls to characters,
	 * for reasons having to do with parser efficiency and input buffering.
	 * It is the programmer's responsibility to deal with that appropriately,
	 * e.g. by accumulating text until the next non-characters event.
	 */
	private void flushTextNode() {
		if (mCharsForTextNode.length() > 0) {
			Text text = mFileDom.createTextNode(mCharsForTextNode.toString());
			mNode.appendChild(text);
			mCharsForTextNode.setLength(0);
		}
	}

	@Override
	public void characters(char[] ch, int start, int length) throws SAXException {
		if (!mHandlerStack.empty()) {
			mHandlerStack.peek().characters(ch, start, length);
		} else {
			mCharsForTextNode.append(ch, start, length);
		}
	}

	@Override
	public InputSource resolveEntity(String publicId, String systemId) throws IOException, SAXException {
		return super.resolveEntity(publicId, systemId);
	}
}