/*

 * Copyright (c) 2016, 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

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 */

import java.lang.instrument.ClassFileTransformer;

import java.lang.instrument.IllegalClassFormatException;

import java.lang.instrument.Instrumentation;

import java.security.ProtectionDomain;

import java.util.HashMap;

// This is a test utility class used to transform

// specified classes via initial transformation (ClassFileLoadHook).

// Names of classes to be transformed are supplied as arguments,

// the phrase to be transformed is a hard-coded predefined

// fairly unique phrase.

public class TransformerAgent {

    private static String[] classesToTransform;

    private static void log(String msg) {

        System.out.println("TransformerAgent: " + msg);

    }

    // arguments are comma-separated list of classes to transform

    public static void premain(String agentArguments, Instrumentation instrumentation) {

        log("premain() is called, arguments = " + agentArguments);

        classesToTransform = agentArguments.split(",");

        instrumentation.addTransformer(new SimpleTransformer(), /*canRetransform=*/true);

    }

    public static void agentmain(String args, Instrumentation inst) throws Exception {

        log("agentmain() is called");

        premain(args, inst);

    }

    static class SimpleTransformer implements ClassFileTransformer {

        public byte[] transform(ClassLoader loader, String name, Class<?> classBeingRedefined,

                                ProtectionDomain pd, byte[] buffer) throws IllegalClassFormatException {

            try {

                log("SimpleTransformer called for: " + name + "@" + incrCounter(name));

                if (!shouldTransform(name))

                    return null;

                log("transforming: class name = " + name);

                int nrOfReplacements = TransformUtil.replace(buffer, TransformUtil.BeforePattern,

                                                           TransformUtil.AfterPattern);

                log("replaced the string, nrOfReplacements = " + nrOfReplacements);

            } catch (Throwable t) {

                // The retransform native code that called this method does not propagate

                // exceptions. Instead of getting an uninformative generic error, catch

                // problems here and print it, then exit.

                log("Transformation failed!");

                t.printStackTrace();

                System.exit(1);

            }

            return buffer;

        }

        // Check class name pattern, since test should only transform certain classes

        private static boolean shouldTransform(String name) {

            for (String match : classesToTransform) {

                if (name.matches(match)) {

                    log("shouldTransform: match-found, match = " + match);

                    return true;

                }

            }

            return false;

        }

    }

    static HashMap<String, Integer> counterMap = new HashMap<>();

    static Integer incrCounter(String className) {

        Integer i = counterMap.get(className);

        if (i == null) {

            i = new Integer(1);

        } else {

            i = new Integer(i.intValue() + 1);

        }

        counterMap.put(className, i);

        return i;

    }

}