/*

 * Copyright (c) 2015, 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.

 */

package compiler.calls.common;

import java.io.FileInputStream;

import java.io.IOException;

import java.lang.invoke.CallSite;

import java.lang.invoke.MethodHandles;

import java.lang.invoke.MethodType;

import java.net.URISyntaxException;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.nio.file.StandardOpenOption;

import jdk.internal.org.objectweb.asm.ClassReader;

import jdk.internal.org.objectweb.asm.ClassVisitor;

import jdk.internal.org.objectweb.asm.ClassWriter;

import jdk.internal.org.objectweb.asm.Handle;

import jdk.internal.org.objectweb.asm.Label;

import jdk.internal.org.objectweb.asm.MethodVisitor;

import jdk.internal.org.objectweb.asm.Opcodes;

/**

 * A class which patch InvokeDynamic class bytecode with invokydynamic

 instruction, rewriting "caller" method to call "callee" method using

 invokedynamic

 */

public class InvokeDynamicPatcher extends ClassVisitor {

    private static final String CLASS = InvokeDynamic.class.getName()

            .replace('.', '/');

    private static final String CALLER_METHOD_NAME = "caller";

    private static final String CALLEE_METHOD_NAME = "callee";

    private static final String NATIVE_CALLEE_METHOD_NAME = "calleeNative";

    private static final String BOOTSTRAP_METHOD_NAME = "bootstrapMethod";

    private static final String CALL_NATIVE_FIELD = "nativeCallee";

    private static final String CALL_NATIVE_FIELD_DESC = "Z";

    private static final String CALLEE_METHOD_DESC

            = "(L" + CLASS + ";IJFDLjava/lang/String;)Z";

    private static final String ASSERTTRUE_METHOD_DESC

            = "(ZLjava/lang/String;)V";

    private static final String ASSERTS_CLASS = "jdk/test/lib/Asserts";

    private static final String ASSERTTRUE_METHOD_NAME = "assertTrue";

    public static void main(String args[]) {

        ClassReader cr;

        Path filePath;

        try {

            filePath = Paths.get(InvokeDynamic.class.getProtectionDomain().getCodeSource()

                    .getLocation().toURI()).resolve(CLASS + ".class");

        } catch (URISyntaxException ex) {

            throw new Error("TESTBUG: Can't get code source" + ex, ex);

        }

        try (FileInputStream fis = new FileInputStream(filePath.toFile())) {

            cr = new ClassReader(fis);

        } catch (IOException e) {

            throw new Error("Error reading file", e);

        }

        ClassWriter cw = new ClassWriter(cr,

                ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS);

        cr.accept(new InvokeDynamicPatcher(Opcodes.ASM5, cw), 0);

        try {

            Files.write(filePath, cw.toByteArray(),

                    StandardOpenOption.WRITE);

        } catch (IOException e) {

            throw new Error(e);

        }

    }

    public InvokeDynamicPatcher(int api, ClassWriter cw) {

        super(api, cw);

    }

    @Override

    public MethodVisitor visitMethod(final int access, final String name,

            final String desc, final String signature,

            final String[] exceptions) {

        /* a code generate looks like

         *  0: aload_0

         *  1: ldc           #125  // int 1

         *  3: ldc2_w        #126  // long 2l

         *  6: ldc           #128  // float 3.0f

         *  8: ldc2_w        #129  // double 4.0d

         * 11: ldc           #132  // String 5

         * 13: aload_0

         * 14: getfield      #135  // Field nativeCallee:Z

         * 17: ifeq          28

         * 20: invokedynamic #181,  0            // InvokeDynamic #1:calleeNative:(Lcompiler/calls/common/InvokeDynamic;IJFDLjava/lang/String;)Z

         * 25: goto          33

         * 28: invokedynamic #183,  0            // InvokeDynamic #1:callee:(Lcompiler/calls/common/InvokeDynamic;IJFDLjava/lang/String;)Z

         * 33: ldc           #185                // String Call insuccessfull

         * 35: invokestatic  #191                // Method jdk/test/lib/Asserts.assertTrue:(ZLjava/lang/String;)V

         * 38: return

         *

         * or, using java-like pseudo-code

         * if (this.nativeCallee == false) {

         *     invokedynamic-call-return-value = invokedynamic-of-callee

         * } else {

         *     invokedynamic-call-return-value = invokedynamic-of-nativeCallee

         * }

         * Asserts.assertTrue(invokedynamic-call-return-value, error-message);

         * return;

         */

        if (name.equals(CALLER_METHOD_NAME)) {

            MethodVisitor mv = cv.visitMethod(access, name, desc,

                    signature, exceptions);

            Label nonNativeLabel = new Label();

            Label checkLabel = new Label();

            MethodType mtype = MethodType.methodType(CallSite.class,

                    MethodHandles.Lookup.class, String.class, MethodType.class);

            Handle bootstrap = new Handle(Opcodes.H_INVOKESTATIC, CLASS,

                    BOOTSTRAP_METHOD_NAME, mtype.toMethodDescriptorString());

            mv.visitCode();

            // push callee parameters onto stack

            mv.visitVarInsn(Opcodes.ALOAD, 0);//push "this"

            mv.visitLdcInsn(1);

            mv.visitLdcInsn(2L);

            mv.visitLdcInsn(3.0f);

            mv.visitLdcInsn(4.0d);

            mv.visitLdcInsn("5");

            // params loaded. let's decide what method to call

            mv.visitVarInsn(Opcodes.ALOAD, 0); // push "this"

            // get nativeCallee field

            mv.visitFieldInsn(Opcodes.GETFIELD, CLASS, CALL_NATIVE_FIELD,

                    CALL_NATIVE_FIELD_DESC);

            // if nativeCallee == false goto nonNativeLabel

            mv.visitJumpInsn(Opcodes.IFEQ, nonNativeLabel);

            // invokedynamic nativeCalleeMethod using bootstrap method

            mv.visitInvokeDynamicInsn(NATIVE_CALLEE_METHOD_NAME,

                    CALLEE_METHOD_DESC, bootstrap);

            // goto checkLabel

            mv.visitJumpInsn(Opcodes.GOTO, checkLabel);

            // label: nonNativeLabel

            mv.visitLabel(nonNativeLabel);

            // invokedynamic calleeMethod using bootstrap method

            mv.visitInvokeDynamicInsn(CALLEE_METHOD_NAME, CALLEE_METHOD_DESC,

                    bootstrap);

            mv.visitLabel(checkLabel);

            mv.visitLdcInsn(CallsBase.CALL_ERR_MSG);

            mv.visitMethodInsn(Opcodes.INVOKESTATIC, ASSERTS_CLASS,

                    ASSERTTRUE_METHOD_NAME, ASSERTTRUE_METHOD_DESC, false);

            // label: return

            mv.visitInsn(Opcodes.RETURN);

            mv.visitMaxs(0, 0);

            mv.visitEnd();

            return null;

        }

        return super.visitMethod(access, name, desc, signature, exceptions);

    }

}