/*

 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * This code is free software; you can redistribute it and/or modify it

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 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

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 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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 * You should have received a copy of the GNU General Public License version

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 *

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/*

 * This file is available under and governed by the GNU General Public

 * License version 2 only, as published by the Free Software Foundation.

 * However, the following notice accompanied the original version of this

 * file, and Oracle licenses the original version of this file under the BSD

 * license:

 */

/*

   Copyright 2009-2013 Attila Szegedi

   Licensed under both the Apache License, Version 2.0 (the "Apache License")

   and the BSD License (the "BSD License"), with licensee being free to

   choose either of the two at their discretion.

   You may not use this file except in compliance with either the Apache

   License or the BSD License.

   If you choose to use this file in compliance with the Apache License, the

   following notice applies to you:

       You may obtain a copy of the Apache License at

           http://www.apache.org/licenses/LICENSE-2.0

       Unless required by applicable law or agreed to in writing, software

       distributed under the License is distributed on an "AS IS" BASIS,

       WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or

       implied. See the License for the specific language governing

       permissions and limitations under the License.

   If you choose to use this file in compliance with the BSD License, the

   following notice applies to you:

       Redistribution and use in source and binary forms, with or without

       modification, are permitted provided that the following conditions are

       met:

       * Redistributions of source code must retain the above copyright

         notice, this list of conditions and the following disclaimer.

       * Redistributions in binary form must reproduce the above copyright

         notice, this list of conditions and the following disclaimer in the

         documentation and/or other materials provided with the distribution.

       * Neither the name of the copyright holder nor the names of

         contributors may be used to endorse or promote products derived from

         this software without specific prior written permission.

       THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

       IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED

       TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A

       PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER

       BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

       CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

       SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR

       BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

       WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR

       OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF

       ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/

package jdk.dynalink;

import java.lang.invoke.MethodHandle;

import java.lang.invoke.MethodHandles;

import java.lang.invoke.MethodHandles.Lookup;

import java.lang.invoke.MethodType;

import java.util.Objects;

import java.util.function.Supplier;

import jdk.dynalink.linker.ConversionComparator.Comparison;

import jdk.dynalink.linker.GuardedInvocation;

import jdk.dynalink.linker.GuardingDynamicLinker;

import jdk.dynalink.linker.LinkRequest;

import jdk.dynalink.linker.LinkerServices;

import jdk.dynalink.linker.MethodHandleTransformer;

/**

 * Default implementation of the {@link LinkerServices} interface.

 */

final class LinkerServicesImpl implements LinkerServices {

    private static final ThreadLocal<SecureLookupSupplier> threadLookupSupplier = new ThreadLocal<>();

    private final TypeConverterFactory typeConverterFactory;

    private final GuardingDynamicLinker topLevelLinker;

    private final MethodHandleTransformer internalObjectsFilter;

    /**

     * Creates a new linker services object.

     *

     * @param typeConverterFactory the type converter factory exposed by the services.

     * @param topLevelLinker the top level linker used by the services.

     * @param internalObjectsFilter a method handle transformer that is supposed to act as the implementation of this

     * services' {@link #filterInternalObjects(java.lang.invoke.MethodHandle)} method.

     */

    LinkerServicesImpl(final TypeConverterFactory typeConverterFactory,

            final GuardingDynamicLinker topLevelLinker, final MethodHandleTransformer internalObjectsFilter) {

        this.typeConverterFactory = typeConverterFactory;

        this.topLevelLinker = topLevelLinker;

        this.internalObjectsFilter = internalObjectsFilter;

    }

    @Override

    public boolean canConvert(final Class<?> from, final Class<?> to) {

        return typeConverterFactory.canConvert(from, to);

    }

    @Override

    public MethodHandle asType(final MethodHandle handle, final MethodType fromType) {

        return typeConverterFactory.asType(handle, fromType);

    }

    @Override

    public MethodHandle getTypeConverter(final Class<?> sourceType, final Class<?> targetType) {

        return typeConverterFactory.getTypeConverter(sourceType, targetType);

    }

    @Override

    public Comparison compareConversion(final Class<?> sourceType, final Class<?> targetType1, final Class<?> targetType2) {

        return typeConverterFactory.compareConversion(sourceType, targetType1, targetType2);

    }

    /**

     * Used to marshal a checked exception out of Supplier.get() in getGuardedInvocation.

     */

    private static class LinkerException extends RuntimeException {

        private static final long serialVersionUID = 1L;

        public LinkerException(final Exception cause) {

            super(null, cause, true, false);

        }

    }

    @Override

    public GuardedInvocation getGuardedInvocation(final LinkRequest linkRequest) throws Exception {

        try {

            return getWithLookupInternal(() -> {

                try {

                    return topLevelLinker.getGuardedInvocation(linkRequest, this);

                } catch (final RuntimeException e) {

                    throw e;

                } catch (final Exception e) {

                    throw new LinkerException(e);

                }

            }, linkRequest.getCallSiteDescriptor());

        } catch (final LinkerException e) {

            throw (Exception)e.getCause();

        }

    }

    @Override

    public MethodHandle filterInternalObjects(final MethodHandle target) {

        return internalObjectsFilter != null ? internalObjectsFilter.transform(target) : target;

    }

    @Override

    public <T> T getWithLookup(final Supplier<T> operation, final SecureLookupSupplier lookupSupplier) {

        return getWithLookupInternal(

                Objects.requireNonNull(operation, "action"),

                Objects.requireNonNull(lookupSupplier, "lookupSupplier"));

    }

    private static <T> T getWithLookupInternal(final Supplier<T> operation, final SecureLookupSupplier lookupSupplier) {

        final SecureLookupSupplier prevLookupSupplier = threadLookupSupplier.get();

        final boolean differ = prevLookupSupplier != lookupSupplier;

        if (differ) {

            threadLookupSupplier.set(lookupSupplier);

        }

        try {

            return operation.get();

        } finally {

            if (differ) {

                threadLookupSupplier.set(prevLookupSupplier);

            }

        }

    }

    static Lookup getCurrentLookup() {

        final SecureLookupSupplier lookupSupplier = threadLookupSupplier.get();

        if (lookupSupplier != null) {

            return lookupSupplier.getLookup();

        }

        return MethodHandles.publicLookup();

    }

}