package net.myvietnam.mvncore.configuration;

/* ====================================================================
 * The Apache Software License, Version 1.1
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 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
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 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
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 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import java.io.IOException;
import java.io.Writer;
import java.util.NoSuchElementException;

import org.apache.commons.digester.Digester;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.io.DOMWriter;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;
import org.xml.sax.SAXException;

/**
 * <p>A helper class that supports XML-like processing for configuration
 * objects.</p>
 * <p>This class provides a set of methods that all have something to do with
 * treating a <code>Configuration</code> object as a XML document. So a
 * configuration can be transformed into a <code>Document</code> (either
 * dom4j or w3c), saved as an XML file or passed to Digester.</p>
 * <p><strong>Implementation note:</strong> This class is not thread safe.</p>
 *
 * @author <a href="mailto:oliver.heger@t-online.de">Oliver Heger</a>
 * @version $Id: ConfigurationXMLDocument.java,v 1.1 2003/12/09 08:25:30 huumai Exp $
 */
public class ConfigurationXMLDocument
{
    /** Constant for the class element.*/
    protected static final String ELEM_CLASS = "config/class";

    /** Constant for the property element.*/
    protected static final String ELEM_PROPERTY = "config/class/property";

    /** Constant for the name attribute.*/
    protected static final String ATTR_NAME = "name";

    /** Constant for the value attribute.*/
    protected static final String ATTR_VALUE = "value";

    /** Stores the configuration object this object operates on.*/
    private Configuration configuration;

    /**
     * Creates a new instance of <code>ConfigurationXMLDocument</code>
     * and sets the configuration object to be processed.
     * @param config the configuration object
     */
    public ConfigurationXMLDocument(Configuration config)
    {
        setConfiguration(config);
    }

    /**
     * Returns the <code>Configuration</code> object for this document.
     * @return the <code>Configuration</code> object
     */
    public Configuration getConfiguration()
    {
        return configuration;
    }

    /**
     * Sets the <code>Configuration</code> object this document operates on.
     * @param configuration the <code>Configuration</code> object
     */
    public void setConfiguration(Configuration configuration)
    {
        this.configuration = configuration;
    }

    /**
     * Returns a <code>XMLReader</code> object for the specified configuration
     * object. This reader can then be used to perform XML-like processing on
     * the configuration.
     * @param config the configuration object
     * @return a XMLReader for this configuration
     */
    public static ConfigurationXMLReader createXMLReader(Configuration config)
    {
        if (config instanceof HierarchicalConfiguration)
        {
            return new HierarchicalConfigurationXMLReader(
                (HierarchicalConfiguration) config);
        } /* if */
        else
        {
            return new BaseConfigurationXMLReader(config);
        } /* else */
    }

    /**
     * Returns a <code>XMLReader</code> object for the actual configuration
     * object.
     * @return a XMLReader for the actual configuration
     */
    public ConfigurationXMLReader createXMLReader()
    {
        return createXMLReader((String) null);
    }

    /**
     * Returns a <code>ConfigurationXMLReader</code> object for the subset
     * configuration specified by the given prefix. If no properties are found
     * under this prefix, a <code>NoSuchElementException</code>
     * exception will be thrown.
     * @param prefix the prefix of the configuration keys that belong to the
     * subset; can be <b>null</b>, then the whole configuration is affected
     * @return a XMLReader for the specified subset configuration
     */
    public ConfigurationXMLReader createXMLReader(String prefix)
    {
        return createXMLReader(configForKey(prefix));
    }

    /**
     * Transforms the wrapped configuration into a dom4j document.
     * @param prefix a prefix for the keys to process; can be <b>null</b>,
     * then all keys in the configuration will be added to the document
     * @param rootName the name of the root element in the document; can be
     * <b>null</b>, then a default name will be used
     * @return the document
     * @throws DocumentException if an error occurs
     */
    public Document getDocument(String prefix, String rootName)
        throws DocumentException
    {
        ConfigurationXMLReader xmlReader = createXMLReader(prefix);
        if (rootName != null)
        {
            xmlReader.setRootName(rootName);
        } /* if */

        SAXReader reader = new SAXReader(xmlReader);
        return reader.read(getClass().getName());
    }

    /**
     * Transforms the wrapped configuration into a dom4j document. The root
     * element will be given a default name.
     * @param prefix a prefix for the keys to process; can be <b>null</b>,
     * then all keys in the configuration will be added to the document
     * @return the document
     * @throws DocumentException if an error occurs
     */
    public Document getDocument(String prefix) throws DocumentException
    {
        return getDocument(prefix, null);
    }

    /**
     * Transforms the wrapped configuration into a dom4j document. The root
     * element will be given a default name.
     * @return the document
     * @throws DocumentException if an error occurs
     */
    public Document getDocument() throws DocumentException
    {
        return getDocument(null, null);
    }

    /**
     * Transforms the wrapped configuration into a w3c document.
     * @param prefix a prefix for the keys to process; can be <b>null</b>,
     * then all keys in the configuration will be added to the document
     * @param rootName the name of the root element in the document; can be
     * <b>null</b>, then a default name will be used
     * @return the document
     * @throws DocumentException if an error occurs
     */
    public org.w3c.dom.Document getW3cDocument(String prefix, String rootName)
        throws DocumentException
    {
        return toW3cDocument(getDocument(prefix, rootName));
    }

    /**