/*

 * 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.naming.internal;

import java.io.InputStream;

import java.io.IOException;

import java.net.MalformedURLException;

import java.net.URL;

import java.util.StringTokenizer;

import java.util.Vector;

import javax.naming.NamingEnumeration;

/**

 * VersionHelper was used by JNDI to accommodate differences between

 * JDK 1.1.x and the Java 2 platform. As this is no longer necessary

 * since JNDI's inclusion in the platform, this class currently

 * serves as a set of utilities for performing system-level things,

 * such as class-loading and reading system properties.

 *

 * @author Rosanna Lee

 * @author Scott Seligman

 */

public abstract class VersionHelper {

    private static VersionHelper helper = null;

    final static String[] PROPS = new String[] {

        javax.naming.Context.INITIAL_CONTEXT_FACTORY,

        javax.naming.Context.OBJECT_FACTORIES,

        javax.naming.Context.URL_PKG_PREFIXES,

        javax.naming.Context.STATE_FACTORIES,

        javax.naming.Context.PROVIDER_URL,

        javax.naming.Context.DNS_URL,

        // The following shouldn't create a runtime dependence on ldap package.

        javax.naming.ldap.LdapContext.CONTROL_FACTORIES

    };

    public final static int INITIAL_CONTEXT_FACTORY = 0;

    public final static int OBJECT_FACTORIES = 1;

    public final static int URL_PKG_PREFIXES = 2;

    public final static int STATE_FACTORIES = 3;

    public final static int PROVIDER_URL = 4;

    public final static int DNS_URL = 5;

    public final static int CONTROL_FACTORIES = 6;

    VersionHelper() {} // Disallow anyone from creating one of these.

    static {

        helper = new VersionHelper12();

    }

    public static VersionHelper getVersionHelper() {

        return helper;

    }

    public abstract Class<?> loadClassWithoutInit(String className)

        throws ClassNotFoundException;

    public abstract Class<?> loadClass(String className)

        throws ClassNotFoundException;

    abstract Class<?> loadClass(String className, ClassLoader cl)

        throws ClassNotFoundException;

    public abstract Class<?> loadClass(String className, String codebase)

        throws ClassNotFoundException, MalformedURLException;

    /*

     * Returns a JNDI property from the system properties.  Returns

     * null if the property is not set, or if there is no permission

     * to read it.

     */

    abstract String getJndiProperty(int i);

    /*

     * Reads each property in PROPS from the system properties, and

     * returns their values -- in order -- in an array.  For each

     * unset property, the corresponding array element is set to null.

     * Returns null if there is no permission to call System.getProperties().

     */

    abstract String[] getJndiProperties();

    /*

     * Returns the resource of a given name associated with a particular

     * class (never null), or null if none can be found.

     */

    abstract InputStream getResourceAsStream(Class<?> c, String name);

    /*

     * Returns an input stream for a file in <java.home>/lib,

     * or null if it cannot be located or opened.

     *

     * @param filename  The file name, sans directory.

     */

    abstract InputStream getJavaHomeLibStream(String filename);

    /*

     * Returns an enumeration (never null) of InputStreams of the

     * resources of a given name associated with a particular class

     * loader.  Null represents the bootstrap class loader in some

     * Java implementations.

     */

    abstract NamingEnumeration<InputStream> getResources(

            ClassLoader cl, String name)

        throws IOException;

    /*

     * Returns the context class loader associated with the current thread.

     * Null indicates the bootstrap class loader in some Java implementations.

     *

     * @throws SecurityException if the class loader is not accessible.

     */

    abstract ClassLoader getContextClassLoader();

    static protected URL[] getUrlArray(String codebase)

        throws MalformedURLException {

        // Parse codebase into separate URLs

        StringTokenizer parser = new StringTokenizer(codebase);

        Vector<String> vec = new Vector<>(10);

        while (parser.hasMoreTokens()) {

            vec.addElement(parser.nextToken());

        }

        String[] url = new String[vec.size()];

        for (int i = 0; i < url.length; i++) {

            url[i] = vec.elementAt(i);

        }

        URL[] urlArray = new URL[url.length];

        for (int i = 0; i < urlArray.length; i++) {

            urlArray[i] = new URL(url[i]);

        }

        return urlArray;

    }

}