/*

 * Copyright (c) 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.

 *

 * 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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 */

package org.graalvm.compiler.replacements.test.classfile;

import static org.junit.Assume.assumeTrue;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.lang.instrument.ClassFileTransformer;

import java.lang.instrument.IllegalClassFormatException;

import java.lang.instrument.Instrumentation;

import java.lang.management.ManagementFactory;

import java.lang.reflect.Method;

import java.nio.file.Files;

import java.nio.file.Path;

import java.security.ProtectionDomain;

import java.util.jar.Attributes;

import java.util.jar.JarEntry;

import java.util.jar.JarOutputStream;

import java.util.jar.Manifest;

import javax.tools.ToolProvider;

import org.junit.Assert;

import org.junit.Test;

import org.graalvm.compiler.api.replacements.ClassSubstitution;

import org.graalvm.compiler.api.replacements.MethodSubstitution;

import org.graalvm.compiler.bytecode.BytecodeProvider;

import org.graalvm.compiler.nodes.graphbuilderconf.GraphBuilderConfiguration;

import org.graalvm.compiler.nodes.graphbuilderconf.InvocationPlugins;

import org.graalvm.compiler.nodes.graphbuilderconf.InvocationPlugins.Registration;

import jdk.vm.ci.meta.ResolvedJavaMethod;

/**

 * Tests that intrinsics (and snippets) are isolated from bytecode instrumentation.

 */

    public static class Original {

        // Intrinsified by Intrinsic.getValue

        public static String getValue() {

            return "original";

        }

    }

    @ClassSubstitution(Original.class)

    private static class Intrinsic {

        @MethodSubstitution

        public static String getValue() {

            return "intrinsic";

        }

    }

    @Override

    protected GraphBuilderConfiguration editGraphBuilderConfiguration(GraphBuilderConfiguration conf) {

        InvocationPlugins invocationPlugins = conf.getPlugins().getInvocationPlugins();

        Registration r = new Registration(invocationPlugins, Original.class, replacementBytecodeProvider);

        r.registerMethodSubstitution(Intrinsic.class, "getValue");

        return super.editGraphBuilderConfiguration(conf);

    }

    public static String callOriginalGetValue() {

        // This call will be intrinsified when compiled by Graal

        return Original.getValue();

    }

    public static String callIntrinsicGetValue() {

        // This call will *not* be intrinsified when compiled by Graal

        return Intrinsic.getValue();

    }

    @Test

    public void test() throws Throwable {

        Object receiver = null;

        Object[] args = {};

        // Prior to redefinition, both Original and Intrinsic

        // should behave as per their Java source code

        Assert.assertEquals("original", Original.getValue());

        Assert.assertEquals("intrinsic", Intrinsic.getValue());

        ResolvedJavaMethod callOriginalGetValue = getResolvedJavaMethod("callOriginalGetValue");

        ResolvedJavaMethod callIntrinsicGetValue = getResolvedJavaMethod("callIntrinsicGetValue");

        // Expect intrinsification to change "original" to "intrinsic"

        testAgainstExpected(callOriginalGetValue, new Result("intrinsic", null), receiver, args);

        // Expect no intrinsification

        testAgainstExpected(callIntrinsicGetValue, new Result("intrinsic", null), receiver, args);

        // Apply redefinition of intrinsic bytecode

        redefineIntrinsic();

        // Expect redefinition to have no effect

        Assert.assertEquals("original", Original.getValue());

        // Expect redefinition to change "intrinsic" to "redefined"

        Assert.assertEquals("redefined", Intrinsic.getValue());

        // Expect redefinition to have no effect on intrinsification (i.e.,

        // "original" is still changed to "intrinsic", not "redefined"

        testAgainstExpected(callOriginalGetValue, new Result("intrinsic", null), receiver, args);

    }

    /**

     * Adds the class file bytes for a given class to a JAR stream.

     */

    static void add(JarOutputStream jar, Class<?> c) throws IOException {

        String name = c.getName();

        String classAsPath = name.replace('.', '/') + ".class";

        jar.putNextEntry(new JarEntry(classAsPath));

        InputStream stream = c.getClassLoader().getResourceAsStream(classAsPath);

        int nRead;

        byte[] buf = new byte[1024];

        while ((nRead = stream.read(buf, 0, buf.length)) != -1) {

            jar.write(buf, 0, nRead);

        }

        jar.closeEntry();

    }

    static void redefineIntrinsic() throws Exception {

        Manifest manifest = new Manifest();

        manifest.getMainAttributes().put(Attributes.Name.MANIFEST_VERSION, "1.0");

        Attributes mainAttrs = manifest.getMainAttributes();

        mainAttrs.putValue("Agent-Class", RedefinerAgent.class.getName());

        mainAttrs.putValue("Can-Redefine-Classes", "true");

        mainAttrs.putValue("Can-Retransform-Classes", "true");

        Path jar = Files.createTempFile("myagent", ".jar");

        try {

            JarOutputStream jarStream = new JarOutputStream(new FileOutputStream(jar.toFile()), manifest);

            add(jarStream, RedefinerAgent.class);

            add(jarStream, Redefiner.class);

            jarStream.close();

            loadAgent(jar);

        } finally {

            Files.deleteIfExists(jar);

        }

    }

    public static void loadAgent(Path agent) throws Exception {

        String vmName = ManagementFactory.getRuntimeMXBean().getName();

        int p = vmName.indexOf('@');

        assumeTrue("VM name not in <pid>@<host> format: " + vmName, p != -1);

        String pid = vmName.substring(0, p);

        Method attach = c.getDeclaredMethod("attach", String.class);

        Method loadAgent = c.getDeclaredMethod("loadAgent", String.class, String.class);

        Method detach = c.getDeclaredMethod("detach");

        Object vm = attach.invoke(null, pid);

        loadAgent.invoke(vm, agent.toString(), "");

        detach.invoke(vm);

    }

    public static class RedefinerAgent {

        public static void agentmain(@SuppressWarnings("unused") String args, Instrumentation inst) throws Exception {

            if (inst.isRedefineClassesSupported() && inst.isRetransformClassesSupported()) {

                inst.addTransformer(new Redefiner(), true);

                Class<?>[] allClasses = inst.getAllLoadedClasses();

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

                    Class<?> c = allClasses[i];

                    if (c == Intrinsic.class) {

                        inst.retransformClasses(new Class<?>[]{c});

                    }

                }

            }

        }

    }

    /**

     * This transformer replaces the first instance of the constant "intrinsic" in the class file

     * for {@link Intrinsic} with "redefined".

     */

    static class Redefiner implements ClassFileTransformer {

        @Override

        public byte[] transform(ClassLoader cl, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {

            if (Intrinsic.class.equals(classBeingRedefined)) {

                String cf = new String(classfileBuffer);

                int i = cf.indexOf("intrinsic");

                Assert.assertTrue("cannot find \"intrinsic\" constant in " + Intrinsic.class.getSimpleName() + "'s class file", i > 0);

                System.arraycopy("redefined".getBytes(), 0, classfileBuffer, i, "redefined".length());

            }

            return classfileBuffer;

        }

    }

}