/*

 * Copyright (c) 2008, 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.

 *

 * 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.

 */

import java.lang.instrument.*;

import java.net.*;

import java.util.*;

import java.io.*;

public class RedefineClassWithNativeMethodAgent {

    static Class clz;

    // just read the original class and redefine it via a Timer

    public static void premain(String agentArgs, final Instrumentation inst) throws Exception {

        String s = agentArgs.substring(0, agentArgs.indexOf(".class"));

        clz = Class.forName(s.replace('/', '.'));

        ClassLoader loader =

            RedefineClassWithNativeMethodAgent.class.getClassLoader();

        URL classURL = loader.getResource(agentArgs);

        if (classURL == null) {

            throw new Exception("Cannot find class: " + agentArgs);

        }

        int         redefineLength;

        InputStream redefineStream;

        System.out.println("Reading test class from " + classURL);

        if (classURL.getProtocol().equals("file")) {

            File f = new File(classURL.getFile());

            redefineStream = new FileInputStream(f);

            redefineLength = (int) f.length();

        } else {

            URLConnection conn = classURL.openConnection();

            redefineStream = conn.getInputStream();

            redefineLength = conn.getContentLength();

        }

        final byte[] buffer = new byte[redefineLength];

        new BufferedInputStream(redefineStream).read(buffer);

        new Timer(true).schedule(new TimerTask() {

            public void run() {

                try {

                    System.out.println("Instrumenting");

                    ClassDefinition cld = new ClassDefinition(clz, buffer);

                    inst.redefineClasses(new ClassDefinition[] { cld });

                }

                catch (Exception e) { e.printStackTrace(); }

            }

        }, 500);

    }

}