/*

 * Copyright (c) 1999, 2011, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.jndi.rmi.registry;

import java.util.Enumeration;

import java.util.Hashtable;

import javax.naming.*;

import javax.naming.spi.*;

import com.sun.jndi.url.rmi.rmiURLContextFactory;

/**

 * A RegistryContextFactory takes an RMI registry reference, and

 * creates the corresponding RMI object or registry context.  In

 * addition, it serves as the initial context factory when using an

 * RMI registry as an initial context.

 *<p>

 * When an initial context is being created, the environment

 * property "java.naming.provider.url" should contain the RMI URL of

 * the appropriate registry.  Otherwise, the default URL "rmi:" is used.

 *<p>

 * An RMI registry reference contains one or more StringRefAddrs of

 * type "URL", each containing a single RMI URL.  Other addresses

 * are ignored.  Multiple URLs represent alternative addresses for the

 * same logical resource.  The order of the addresses is not significant.

 *

 * @author Scott Seligman

 */

public class RegistryContextFactory

        implements ObjectFactory, InitialContextFactory

{

    /**

     * The type of each address in an RMI registry reference.

     */

    public final static String ADDRESS_TYPE = "URL";

    public Context getInitialContext(Hashtable<?,?> env) throws NamingException {

        if (env != null) {

            env = (Hashtable) env.clone();

        }

        return URLToContext(getInitCtxURL(env), env);

    }

    public Object getObjectInstance(Object ref, Name name, Context nameCtx,

                                    Hashtable<?,?> env)

            throws NamingException

    {

        if (!isRegistryRef(ref)) {

            return null;

        }

        /*

         * No need to clone env here.  If getObjectInstance()

         * returns something other than a RegistryContext (which

         * happens if you're looking up an object bound in the

         * registry, as opposed to looking up the registry itself),

         * then the context is GCed right away and there's no need to

         * clone the environment.  If getObjectInstance() returns a

         * RegistryContext, then it still goes through

         * GenericURLContext, which calls RegistryContext.lookup()

         * with an empty name, which clones the environment.

         */

        Object obj = URLsToObject(getURLs((Reference)ref), env);

        if (obj instanceof RegistryContext) {

            RegistryContext ctx = (RegistryContext)obj;

            ctx.reference = (Reference)ref;

        }

        return obj;

    }

    private static Context URLToContext(String url, Hashtable<?,?> env)

            throws NamingException

    {

        rmiURLContextFactory factory = new rmiURLContextFactory();

        Object obj = factory.getObjectInstance(url, null, null, env);

        if (obj instanceof Context) {

            return (Context)obj;

        } else {

            throw (new NotContextException(url));

        }

    }

    private static Object URLsToObject(String[] urls, Hashtable<?,?> env)

            throws NamingException

    {

        rmiURLContextFactory factory = new rmiURLContextFactory();

        return factory.getObjectInstance(urls, null, null, env);

    }

    /**

     * Reads environment to find URL of initial context.

     * The default URL is "rmi:".

     */

    private static String getInitCtxURL(Hashtable<?,?> env) {

        final String defaultURL = "rmi:";

        String url = null;

        if (env != null) {

            url = (String)env.get(Context.PROVIDER_URL);

        }

        return ((url != null) ? url : defaultURL);

    }

    /**

     * Returns true if argument is an RMI registry reference.

     */

    private static boolean isRegistryRef(Object obj) {

        if (!(obj instanceof Reference)) {

            return false;

        }

        String thisClassName = RegistryContextFactory.class.getName();

        Reference ref = (Reference)obj;

        return thisClassName.equals(ref.getFactoryClassName());

    }

    /**

     * Returns the URLs contained within an RMI registry reference.

     */

    private static String[] getURLs(Reference ref) throws NamingException {

        int size = 0;   // number of URLs

        String[] urls = new String[ref.size()];

        Enumeration<RefAddr> addrs = ref.getAll();

        while (addrs.hasMoreElements()) {

            RefAddr addr = addrs.nextElement();

            if ((addr instanceof StringRefAddr) &&

                addr.getType().equals(ADDRESS_TYPE)) {

                urls[size++] = (String)addr.getContent();

            }

        }

        if (size == 0) {

            throw (new ConfigurationException(

                    "Reference contains no valid addresses"));

        }

        // Trim URL array down to size.

        if (size == ref.size()) {

            return urls;

        }

        String[] urls2 = new String[size];

        System.arraycopy(urls, 0, urls2, 0, size);

        return urls2;

    }

}