/*

 * Copyright (c) 2012, 2018, 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

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 */

package jdk.jfr.internal.instrument;

import java.io.ByteArrayInputStream;

import java.io.IOException;

import java.io.InputStream;

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.MethodVisitor;

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

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

final class ConstructorTracerWriter extends ClassVisitor {

    private ConstructorWriter useInputParameter, noUseInputParameter;

    static byte[] generateBytes(Class<?> clz, byte[] oldBytes) throws IOException {

        InputStream in = new ByteArrayInputStream(oldBytes);

        ClassReader cr = new ClassReader(in);

        ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS);

        ConstructorTracerWriter ctw = new ConstructorTracerWriter(cw, clz);

        cr.accept(ctw, 0);

        return cw.toByteArray();

    }

    private ConstructorTracerWriter(ClassVisitor cv, Class<?> classToChange) {

        super(Opcodes.ASM5, cv);

        useInputParameter = new ConstructorWriter(classToChange, true);

        noUseInputParameter = new ConstructorWriter(classToChange, false);

    }

    private boolean isConstructor(String name) {

        return name.equals("<init>");

    }

    private boolean takesStringParameter(String desc) {

        Type[] types = Type.getArgumentTypes(desc);

        if (types.length > 0 && types[0].getClassName().equals(String.class.getName())) {

            return true;

        }

        return false;

    }

    @Override

    public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {

        MethodVisitor mv = super.visitMethod(access, name, desc, signature, exceptions);

        // Get a hold of the constructors that takes a String as a parameter

        if (isConstructor(name)) {

            if (takesStringParameter(desc)) {

                useInputParameter.setMethodVisitor(mv);

                return useInputParameter;

            }

            noUseInputParameter.setMethodVisitor(mv);

            return noUseInputParameter;

        }

        return mv;

    }

}