/*
 * Copyright (c) 2017, 2017, 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 com.oracle.svm.reflect.hosted;

// Checkstyle: allow reflection

import java.lang.reflect.Member;
import java.lang.reflect.Proxy;

import org.graalvm.compiler.serviceprovider.GraalUnsafeAccess;
import org.graalvm.nativeimage.ImageSingletons;

import com.oracle.svm.core.annotate.RecomputeFieldValue;
import com.oracle.svm.core.util.VMError;
import com.oracle.svm.reflect.helpers.ReflectionProxyHelper;

import jdk.vm.ci.meta.MetaAccessProvider;
import jdk.vm.ci.meta.ResolvedJavaField;
import sun.misc.Unsafe;

public final class AccessorComputer implements RecomputeFieldValue.CustomFieldValueComputer {

    private static final Unsafe UNSAFE = GraalUnsafeAccess.getUnsafe();

    @Override
    public Object compute(MetaAccessProvider metaAccess, ResolvedJavaField original, ResolvedJavaField annotated, Object receiver) {
        Member member = (Member) receiver;
        ReflectionSubstitution subst = ImageSingletons.lookup(ReflectionSubstitution.class);
        Class<?> proxyClass = subst.getProxyClass(member);
        if (proxyClass == null) {
            // should never happen, but better check for it here than segfault later
            throw VMError.shouldNotReachHere();
        }
        try {
            Proxy proxyInstance = (Proxy) UNSAFE.allocateInstance(proxyClass);
            ReflectionProxyHelper.setDefaultInvocationHandler(proxyInstance);
            return proxyInstance;

        } catch (InstantiationException ex) {
            throw VMError.shouldNotReachHere(ex);
        }
    }
}