/*

 * 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.lang.annotation.Annotation;

import java.lang.reflect.InvocationHandler;

import java.lang.reflect.Method;

import java.lang.reflect.Proxy;

import java.util.Collections;

import java.util.List;

import jdk.jfr.AnnotationElement;

import jdk.jfr.Description;

import jdk.jfr.Label;

import jdk.jfr.Unsigned;

public final class AnnotationConstruct {

    private static final class AnnotationInvokationHandler implements InvocationHandler {

        private final AnnotationElement annotationElement;

        AnnotationInvokationHandler(AnnotationElement a) {

            this.annotationElement = a;

        }

        @Override

        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

            String methodName = method.getName();

            int parameters = method.getTypeParameters().length;

            if (parameters == 0 && annotationElement.hasValue(methodName)) {

                return annotationElement.getValue(methodName);

            }

            throw new UnsupportedOperationException("Flight Recorder proxy only supports members declared in annotation interfaces, i.e. not toString, equals etc.");

        }

    }

    private List<AnnotationElement> annotationElements = Collections.emptyList();

    private byte unsignedFlag = -1;

    public AnnotationConstruct(List<AnnotationElement> ann) {

        this.annotationElements = ann;

    }

    public AnnotationConstruct() {

    }

    public void setAnnotationElements(List<AnnotationElement> elements) {

        annotationElements = Utils.smallUnmodifiable(elements);

    }

    public String getLabel() {

        Label label = getAnnotation(Label.class);

        if (label == null) {

            return null;

        }

        return label.value();

    }

    public String getDescription() {

        Description description = getAnnotation(Description.class);

        if (description == null) {

            return null;

        }

        return description.value();

    }

    @SuppressWarnings("unchecked")

    public final <T> T getAnnotation(Class<? extends Annotation> clazz) {

        AnnotationElement ae = getAnnotationElement(clazz);

        if (ae != null) {

            return (T) Proxy.newProxyInstance(clazz.getClassLoader(), new Class<?>[] { clazz }, new AnnotationInvokationHandler(ae));

        }

        return null;

    }

    public List<AnnotationElement> getUnmodifiableAnnotationElements() {

        return annotationElements;

    }

    // package private

    boolean remove(AnnotationElement annotation) {

        return annotationElements.remove(annotation);

    }

    private AnnotationElement getAnnotationElement(Class<? extends Annotation> clazz) {

        // if multiple annotation elements with the same name exists, prioritize

        // the one with the same id. Note, id alone is not a guarantee, since it

        // may differ between JVM instances.

        long id = Type.getTypeId(clazz);

        String className = clazz.getName();

        for (AnnotationElement a : getUnmodifiableAnnotationElements()) {

            if (a.getTypeId() == id && a.getTypeName().equals(className)) {

                return a;

            }

        }

        for (AnnotationElement a : getUnmodifiableAnnotationElements()) {

            if (a.getTypeName().equals(className)) {

                return a;

            }

        }

        return null;

    }

    public boolean hasUnsigned() {

        // Must be initialized lazily since some annotation elements

        // are added after construction

        if (unsignedFlag < 0) {

            Unsigned unsigned = getAnnotation(Unsigned.class);

            unsignedFlag = (byte) (unsigned == null ? 0 :1);

        }

        return unsignedFlag == (byte)1 ? true : false;

    }

}