//----------------------------BEGIN LICENSE----------------------------
/* 
 * Willow : the Open Source WorkFlow Project
 * Distributable under GNU LGPL license by gun.org
 *
 * Copyright (C) 2004-2010  huihoo.org 
 * Copyright (C) 2004-2010  ZosaTapo <dertyang@hotmail.com> 
 * 
 * ====================================================================
 * Project Homepage : http://www.huihoo.org/willow
 * Source Forge     : http://sourceforge.net/projects/huihoo
 * Mailing list     : willow@lists.sourceforge.net 
 */
//----------------------------END  LICENSE-----------------------------
package org.huihoo.willow.startup;

import java.util.HashMap;

import org.apache.commons.digester.Digester;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;


public class SchemaResolver implements EntityResolver
{

	/**
	 * The disgester instance for which this class is the entity resolver.
	 */
	protected Digester digester;

	/**
	 * The URLs of dtds and schemas that have been registered, keyed by the
	 * public identifier that corresponds.
	 */
	protected HashMap entityValidator = new HashMap();

	/**
	 * The public identifier of the DTD we are currently parsing under
	 * (if any).
	 */
	protected String publicId = null;

	/**
	 * Extension to make the difference between DTD and Schema.
	 */
	protected String schemaExtension = "xsd";

	/**
	 * Create a new <code>EntityResolver</code> that will redirect
	 * all remote dtds and schema to a locat destination.
	 * @param schemaLocation the XML Schema used to validate xml instance.
	 */
	public SchemaResolver(Digester digester)
	{
		this.digester = digester;
	}

	/**
	 * Register the specified DTD/Schema URL for the specified public
	 * identifier. This must be called before the first call to
	 * <code>parse()</code>.
	 *
	 * When adding a schema file (*.xsd), only the name of the file
	 * will get added. If two schemas with the same name are added,
	 * only the last one will be stored.
	 *
	 * @param publicId Public identifier of the DTD to be resolved
	 * @param entityURL The URL to use for reading this DTD
	 */
	public void register(String publicId, String entityURL)
	{
		String key = publicId;
		if (publicId.indexOf(schemaExtension) != -1)
		{
		  key = publicId.substring(publicId.lastIndexOf('/') + 1);
		}
		entityValidator.put(key, entityURL);
	}

	/**
	 * Resolve the requested external entity.
	 *
	 * @param publicId The public identifier of the entity being referenced
	 * @param systemId The system identifier of the entity being referenced
	 *
	 * @exception SAXException if a parsing exception occurs
	 *
	 */
	public InputSource resolveEntity(String publicId, String systemId) throws SAXException
	{
//		System.err.println("--------------------------------------------");
//		System.err.println("publicId ====> "+publicId);
//		System.err.println("systemId ====> "+systemId);
//		
		if (publicId != null)
		{
			this.publicId = publicId;
			digester.setPublicId(publicId);
		}

		// Has this system identifier been registered?
		String entityURL = null;
		if (publicId != null)
		{
			entityURL = (String) entityValidator.get(publicId);
		}

		// Redirect the schema location to a local destination
		String key = null;
		if (entityURL == null && systemId != null)
		{
			key = systemId.substring(systemId.lastIndexOf('/') + 1);
			entityURL = (String) entityValidator.get(key);
		}

		if (entityURL == null)
		{
			return (null);
		}

		try
		{
			return (new InputSource(entityURL));
		}
		catch (Exception e)
		{
			throw new SAXException(e);
		}

	}

}
