/*

 * Copyright (c) 2016, 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

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package jdk.jfr.internal;

import java.util.List;

import java.util.concurrent.atomic.AtomicLong;

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

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

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

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

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

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

import jdk.internal.org.objectweb.asm.commons.GeneratorAdapter;

import jdk.internal.org.objectweb.asm.commons.Method;

import jdk.jfr.AnnotationElement;

import jdk.jfr.Event;

import jdk.jfr.ValueDescriptor;

// Helper class for building dynamic events

public final class EventClassBuilder {

    private static final Type TYPE_EVENT = Type.getType(Event.class);

    private static final Type TYPE_IOBE = Type.getType(IndexOutOfBoundsException.class);

    private static final Method DEFAULT_CONSTRUCTOR = Method.getMethod("void <init> ()");

    private static final Method SET_METHOD = Method.getMethod("void set (int, java.lang.Object)");

    private static final AtomicLong idCounter = new AtomicLong();

    private final ClassWriter classWriter = new ClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);

    private final String fullClassName;

    private final Type type;

    private final List<ValueDescriptor> fields;

    private final List<AnnotationElement> annotationElements;

    public EventClassBuilder(List<AnnotationElement> annotationElements, List<ValueDescriptor> fields) {

        this.fullClassName = "jdk.jfr.DynamicEvent" + idCounter.incrementAndGet();

        this.type = Type.getType(fullClassName.replace(".", "/"));

        this.fields = fields;

        this.annotationElements = annotationElements;

    }

    public Class<? extends Event> build() {

        buildClassInfo();

        buildConstructor();

        buildFields();

        buildSetMethod();

        endClass();

        byte[] bytes = classWriter.toByteArray();

        ASMToolkit.logASM(fullClassName, bytes);

        return SecuritySupport.defineClass(type.getInternalName(), bytes, Event.class.getClassLoader()).asSubclass(Event.class);

    }

    private void endClass() {

        classWriter.visitEnd();

    }

    private void buildSetMethod() {

        GeneratorAdapter ga = new GeneratorAdapter(Opcodes.ACC_PUBLIC, SET_METHOD, null, null, classWriter);

        int index = 0;

        for (ValueDescriptor v : fields) {

            ga.loadArg(0);

            ga.visitLdcInsn(index);

            Label notEqual = new Label();

            ga.ifICmp(GeneratorAdapter.NE, notEqual);

            ga.loadThis();

            ga.loadArg(1);

            Type fieldType = ASMToolkit.toType(v);

            ga.unbox(ASMToolkit.toType(v));

            ga.putField(type, v.getName(), fieldType);

            ga.visitInsn(Opcodes.RETURN);

            ga.visitLabel(notEqual);

            index++;

        }

        ga.throwException(TYPE_IOBE, "Index must between 0 and " + fields.size());

        ga.endMethod();

    }

    private void buildConstructor() {

        MethodVisitor mv = classWriter.visitMethod(Opcodes.ACC_PUBLIC, DEFAULT_CONSTRUCTOR.getName(), DEFAULT_CONSTRUCTOR.getDescriptor(), null, null);

        mv.visitIntInsn(Opcodes.ALOAD, 0);

        ASMToolkit.invokeSpecial(mv, TYPE_EVENT.getInternalName(), DEFAULT_CONSTRUCTOR);

        mv.visitInsn(Opcodes.RETURN);

        mv.visitMaxs(0, 0);

    }

    private void buildClassInfo() {

        String internalSuperName = ASMToolkit.getInternalName(Event.class.getName());

        String internalClassName = type.getInternalName();

        classWriter.visit(52, Opcodes.ACC_PUBLIC + Opcodes.ACC_FINAL + Opcodes.ACC_SUPER, internalClassName, null, internalSuperName, null);

        for (AnnotationElement a : annotationElements) {

            String descriptor = ASMToolkit.getDescriptor(a.getTypeName());

            AnnotationVisitor av = classWriter.visitAnnotation(descriptor, true);

            for (ValueDescriptor v : a.getValueDescriptors()) {

                Object value = a.getValue(v.getName());

                String name = v.getName();

                if (v.isArray()) {

                    AnnotationVisitor arrayVisitor = av.visitArray(name);

                    Object[] array = (Object[]) value;

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

                        arrayVisitor.visit(null, array[i]);

                    }

                    arrayVisitor.visitEnd();

                } else {

                    av.visit(name, value);

                }

            }

            av.visitEnd();

        }

    }

    private void buildFields() {

        for (ValueDescriptor v : fields) {

            String internal = ASMToolkit.getDescriptor(v.getTypeName());

            classWriter.visitField(Opcodes.ACC_PRIVATE, v.getName(), internal, null, null);

            // No need to store annotations on field since they will be replaced anyway.

        }

    }

}