/*******************************************************************************
 * Copyright (c) 1998, 2008 IBM Corporation and Others
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Goh KONDOH - initial API and implementation
 *******************************************************************************/

package org.eclipse.actf.model.dom.sgml.errorhandler;

import java.io.IOException;

import org.eclipse.actf.model.dom.sgml.ElementDefinition;
import org.eclipse.actf.model.dom.sgml.ParseException;
import org.eclipse.actf.model.dom.sgml.SGMLParser;
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;
import org.xml.sax.SAXException;


/**
 *  An implementation of {@link IErrorHandler}
 */
public class DefaultErrorHandler implements IErrorHandler {
    /**
     * Set appropriate context element to context if an error occurs.
     * <ol>
     * <li> If <code>node</code> is a singleton instance, find another 
     * element with the same name.  And if the other has no attribute, 
     * merge them.
     * <li> If current context has already an illegal children,
     * it fails (Since ver.1.1.a7).
     * <li> If <code>errorNode</code> is unknown element, fail.
     * <!--
     * <li> if <code>errorNode</code> is an element with the same name as context 
     * and has no attribute, it interpret <code>errorNode</code> as endtag.
     * <li> If <code>node</code> is and Element and empty child element, it also fails.
     * <li> Otherwise searches a proper parent from current context
     * to outer-most and right-most node.
     * -->
     * </ol>
     * @param node illegal child 
     * @return true if found, otherwise false
     * @see SGMLParser#getContext()
     * @see SGMLParser#setContext(org.w3c.dom.Element)
     */
    public boolean handleError(int code, SGMLParser parser, Node errorNode)
	throws ParseException, IOException, SAXException {
	if (errorNode instanceof Element) { 
	    Element element = (Element)errorNode;
	    String elementName = element.getTagName();
	    ElementDefinition ed;
	    if ((ed = parser.getDTD().getElementDefinition(elementName)) == null) {
		return false;
	    } else if (ed.isSingleton()) {
		NodeList others = parser.getDocument().getElementsByTagName(elementName);
		if (others.getLength() == 1) {
		    Element another = (Element)others.item(0);
		    if (parser.autoGenerated(another)) {
			NamedNodeMap attributes = element.getAttributes();
			for (int i = 0; i < attributes.getLength(); i++) {
			    Attr attr = (Attr)attributes.item(i);
			    element.removeAttributeNode(attr);
			    another.setAttributeNode(attr);
			}
			parser.setCurrentNode(another);
			parser.setContext(another);
			parser.error(ILLEGAL_CHILD, errorNode + " and " + another +
				     " are duplicated.");
			return true;
		    }
		}
	    }
	}
	return false;
    }
}