/*
 * Copyright (c) 2015, 2016, 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
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 */
package org.graalvm.compiler.hotspot;

import static org.graalvm.compiler.core.common.util.ModuleAPI.addExports;
import static org.graalvm.compiler.core.common.util.ModuleAPI.addOpens;
import static org.graalvm.compiler.core.common.util.ModuleAPI.getModule;
import static org.graalvm.compiler.core.common.util.Util.JAVA_SPECIFICATION_VERSION;

import org.graalvm.compiler.serviceprovider.ServiceProvider;

import jdk.vm.ci.hotspot.HotSpotVMEventListener;
import jdk.vm.ci.runtime.JVMCICompilerFactory;
import jdk.vm.ci.services.JVMCIServiceLocator;
import jdk.vm.ci.services.Services;

@ServiceProvider(JVMCIServiceLocator.class)
public final class HotSpotGraalJVMCIServiceLocator extends JVMCIServiceLocator {

    /**
     * Holds the state shared between all {@link HotSpotGraalJVMCIServiceLocator} instances. This is
     * necessary as {@link Services} can create a new instance of a service provider each time
     * {@link Services#load(Class)} or {@link Services#loadSingle(Class, boolean)} is called.
     */
    private static final class Shared {
        static final Shared SINGLETON = new Shared();

        private boolean exportsAdded;

        /**
         * Dynamically exports and opens various internal JDK packages to the Graal module. This
         * requires only a single {@code --add-exports=java.base/jdk.internal.module=<Graal module>}
         * on the VM command line instead of a {@code --add-exports} instance for each JDK internal
         * package used by Graal.
         */
        private void addExports() {
            if (JAVA_SPECIFICATION_VERSION >= 9 && !exportsAdded) {
                Object javaBaseModule = getModule.invoke(String.class);
                Object graalModule = getModule.invoke(getClass());
                addExports.invokeStatic(javaBaseModule, "jdk.internal.misc", graalModule);
                addExports.invokeStatic(javaBaseModule, "jdk.internal.jimage", graalModule);
                addExports.invokeStatic(javaBaseModule, "com.sun.crypto.provider", graalModule);
                addOpens.invokeStatic(javaBaseModule, "jdk.internal.misc", graalModule);
                addOpens.invokeStatic(javaBaseModule, "jdk.internal.jimage", graalModule);
                addOpens.invokeStatic(javaBaseModule, "com.sun.crypto.provider", graalModule);
                exportsAdded = true;
            }
        }

        <T> T getProvider(Class<T> service, HotSpotGraalJVMCIServiceLocator locator) {
            if (service == JVMCICompilerFactory.class) {
                addExports();
                return service.cast(new HotSpotGraalCompilerFactory(locator));
            } else if (service == HotSpotVMEventListener.class) {
                if (graalRuntime != null) {
                    addExports();
                    return service.cast(new HotSpotGraalVMEventListener(graalRuntime));
                }
            }
            return null;
        }

        private HotSpotGraalRuntime graalRuntime;

        /**
         * Notifies this object of the compiler created via {@link HotSpotGraalJVMCIServiceLocator}.
         */
        void onCompilerCreation(HotSpotGraalCompiler compiler) {
            assert this.graalRuntime == null : "only expect a single JVMCICompiler to be created";
            this.graalRuntime = (HotSpotGraalRuntime) compiler.getGraalRuntime();
        }
    }

    @Override
    public <T> T getProvider(Class<T> service) {
        return Shared.SINGLETON.getProvider(service, this);
    }

    /**
     * Notifies this object of the compiler created via {@link HotSpotGraalJVMCIServiceLocator}.
     */
    @SuppressWarnings("static-method")
    void onCompilerCreation(HotSpotGraalCompiler compiler) {
        Shared.SINGLETON.onCompilerCreation(compiler);
    }
}