/*

 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.

 *

 * 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 Oracle nor the names of its

 *     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 THE COPYRIGHT OWNER OR

 * CONTRIBUTORS 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.

 */

import java.lang.invoke.MethodHandle;

import java.lang.invoke.MethodType;

import java.util.ArrayList;

import java.util.List;

import java.util.stream.DoubleStream;

import java.util.stream.IntStream;

import java.util.stream.LongStream;

import java.util.stream.Stream;

import jdk.dynalink.CallSiteDescriptor;

import jdk.dynalink.NamedOperation;

import jdk.dynalink.NamespaceOperation;

import jdk.dynalink.Operation;

import jdk.dynalink.StandardNamespace;

import jdk.dynalink.StandardOperation;

import jdk.dynalink.linker.GuardedInvocation;

import jdk.dynalink.linker.GuardingDynamicLinker;

import jdk.dynalink.linker.GuardingDynamicLinkerExporter;

import jdk.dynalink.linker.LinkRequest;

import jdk.dynalink.linker.LinkerServices;

import jdk.dynalink.linker.TypeBasedGuardingDynamicLinker;

import jdk.dynalink.linker.support.Guards;

import jdk.dynalink.linker.support.Lookup;

/**

 * This is a dynalink pluggable linker (see http://openjdk.java.net/jeps/276).

 * This linker adds "stream" property to Java arrays. The appropriate Stream

 * type object is returned for "stream" property on Java arrays. Note that

 * the dynalink beans linker just adds "length" property and Java array objects

 * don't have any other property. "stream" property does not conflict with anything

 * else!

 */

public final class ArrayStreamLinkerExporter extends GuardingDynamicLinkerExporter {

    static {

        System.out.println("pluggable dynalink array stream linker loaded");

    }

    public static Object arrayToStream(final Object array) {

        if (array instanceof int[]) {

            return IntStream.of((int[])array);

        } else if (array instanceof long[]) {

            return LongStream.of((long[])array);

        } else if (array instanceof double[]) {

            return DoubleStream.of((double[])array);

        } else if (array instanceof Object[]) {

            return Stream.of((Object[])array);

        } else {

            throw new IllegalArgumentException();

        }

    }

    private static final MethodType GUARD_TYPE = MethodType.methodType(Boolean.TYPE, Object.class);

    private static final MethodHandle ARRAY_TO_STREAM = Lookup.PUBLIC.findStatic(

            ArrayStreamLinkerExporter.class, "arrayToStream",

            MethodType.methodType(Object.class, Object.class));

    @Override

    public List<GuardingDynamicLinker> get() {

        final ArrayList<GuardingDynamicLinker> linkers = new ArrayList<>();

        linkers.add(new TypeBasedGuardingDynamicLinker() {

            @Override

            public boolean canLinkType(final Class<?> type) {

                return type == Object[].class || type == int[].class ||

                       type == long[].class || type == double[].class;

            }

            @Override

            public GuardedInvocation getGuardedInvocation(final LinkRequest request,

                final LinkerServices linkerServices) throws Exception {

                final Object self = request.getReceiver();

                if (self == null || !canLinkType(self.getClass())) {

                    return null;

                }

                final CallSiteDescriptor desc = request.getCallSiteDescriptor();

                final Operation op = desc.getOperation();

                final Object name = NamedOperation.getName(op);

                final boolean getProp = NamespaceOperation.contains(

                        NamedOperation.getBaseOperation(op),

                        StandardOperation.GET, StandardNamespace.PROPERTY);

                if (getProp && "stream".equals(name)) {

                    return new GuardedInvocation(ARRAY_TO_STREAM,

                        Guards.isOfClass(self.getClass(), GUARD_TYPE));

                }

                return null;

            }

        });

        return linkers;

    }

}