/*******************************************************************************
 * Copyright (c) 1998, 2008 Oracle. All rights reserved.
 * This program and the accompanying materials are made available under the 
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0 
 * which accompanies this distribution. 
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at 
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
 ******************************************************************************/  
package org.eclipse.persistence.internal.sessions.factories;

import java.io.InputStream;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.util.Hashtable;
import java.util.Enumeration;

import org.eclipse.persistence.internal.security.PrivilegedAccessHelper;
import org.eclipse.persistence.internal.security.PrivilegedGetClassLoaderForClass;

import org.xml.sax.InputSource;
import org.xml.sax.EntityResolver;

/**
 * INTERNAL:
 * <p><b>Purpose</b>: Provide a mechanism for retrieving the DTD file
 * from the classpath
 *
 * @see org.xml.sax.EntityResolver
 * @since TopLink 10.1.3
 * @author Gordon Yorke, Guy Pelletier
 */
public class PersistenceEntityResolver implements EntityResolver {
    protected Hashtable m_localResources;
    protected static final String dtdFileName40 = "sessions_4_0.dtd";
    protected static final String doctTypeId40 = "-//Oracle Corp.//DTD TopLink for JAVA 4.0//EN";
    protected static final String dtdFileName45 = "sessions_4_5.dtd";
    protected static final String doctTypeId45 = "-//Oracle Corp.//DTD TopLink for JAVA 4.5//EN";
    protected static final String dtdFileName904 = "sessions_9_0_4.dtd";
    protected static final String doctTypeId904 = "-//Oracle Corp.//DTD TopLink Sessions 9.0.4//EN";

    /**
     * INTERNAL:
     */
    public PersistenceEntityResolver() {
        m_localResources = new Hashtable();
        populateLocalResources();
    }

    /**
     * INTERNAL:
     */
    protected void populateLocalResources() {
        m_localResources.put(doctTypeId40, dtdFileName40);
        m_localResources.put(doctTypeId45, dtdFileName45);
        m_localResources.put(doctTypeId904, dtdFileName904);
    }

    /**
     * INTERNAL:
     */
    protected String getDtdFileName(String docTypeId) {
        return (String)getLocalResources().get(docTypeId);
    }

    /**
     * INTERNAL:
     */
    public Hashtable getLocalResources() {
        return m_localResources;
    }

    /**
     * INTERNAL:
     */
    public void setLocalResources(Hashtable ht) {
        m_localResources = ht;
    }

    /**
     * INTERNAL:
     */
    public void addLocalResource(String publicId, String localFileName) {
        m_localResources.put(publicId, localFileName);
    }

    /**
     * INTERNAL:
     */
    public InputSource resolveEntity(String publicId, String systemId) {
        for (Enumeration docTypeIds = m_localResources.keys(); docTypeIds.hasMoreElements();) {
            String docTypeId = (String)docTypeIds.nextElement();

            if ((publicId != null) && publicId.equals(docTypeId)) {
                InputStream localDtdStream =  null;
                if (PrivilegedAccessHelper.shouldUsePrivilegedAccess()){
                    try{
                        localDtdStream = ((ClassLoader)AccessController.doPrivileged(new PrivilegedGetClassLoaderForClass(getClass()))).getResourceAsStream(getDtdFileName(docTypeId));
                    }catch (PrivilegedActionException ex){
                        throw (RuntimeException) ex.getCause();
                    }
                }else{
                    localDtdStream = PrivilegedAccessHelper.getClassLoaderForClass(getClass()).getResourceAsStream(getDtdFileName(docTypeId));

                }
                if (localDtdStream != null) {
                    return new InputSource(localDtdStream);
                }
            }
        }

        return null;
    }
}