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/**
 * Copyright 2009-2015 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the 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.
 */
package net.javacrumbs.futureconverter.springguava;

import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.MoreExecutors;
import net.javacrumbs.futureconverter.common.FutureWrapper;
import org.springframework.util.concurrent.ListenableFuture;
import org.springframework.util.concurrent.ListenableFutureCallback;

import java.util.concurrent.Executor;

/**
 * Converts between Guava {@link com.google.common.util.concurrent.ListenableFuture} and Spring 4 {@link org.springframework.util.concurrent.ListenableFuture}.
 */
public class FutureConverter {

    /**
     * Converts Guava {@link com.google.common.util.concurrent.ListenableFuture} to Spring 4 {@link org.springframework.util.concurrent.ListenableFuture}
     *
     * @param guavaListenableFuture
     * @param 
     * @return
     */
    public static  ListenableFuture toSpringListenableFuture(com.google.common.util.concurrent.ListenableFuture guavaListenableFuture) {
        if (guavaListenableFuture instanceof GuavaListenableWrappingSpringListenableFuture) {
            return ((GuavaListenableWrappingSpringListenableFuture) guavaListenableFuture).getWrappedFuture();
        } else {
            return new SpringListenableWrappingGuavaListenableFuture(guavaListenableFuture);
        }
    }

    /**
     * Converts Spring 4 {@link org.springframework.util.concurrent.ListenableFuture}
     * to Guava {@link com.google.common.util.concurrent.ListenableFuture}.
     *
     * @param springListenableFuture
     * @param 
     * @return
     */
    public static  com.google.common.util.concurrent.ListenableFuture toGuavaListenableFuture(ListenableFuture springListenableFuture) {
        if (springListenableFuture instanceof SpringListenableWrappingGuavaListenableFuture) {
            return ((SpringListenableWrappingGuavaListenableFuture) springListenableFuture).getWrappedFuture();
        } else {
            return new GuavaListenableWrappingSpringListenableFuture(springListenableFuture);
        }
    }

    /**
     * Wraps Guava ListenableFuture to Spring ListenableFuture.
     *
     * @param 
     */
    private static class SpringListenableWrappingGuavaListenableFuture extends FutureWrapper implements ListenableFuture {
        public SpringListenableWrappingGuavaListenableFuture(com.google.common.util.concurrent.ListenableFuture guavaListenableFuture) {
            super(guavaListenableFuture);
        }

        @Override
        public void addCallback(final ListenableFutureCallback callback) {
            Futures.addCallback(getWrappedFuture(), new FutureCallback() {
                @Override
                public void onSuccess(T result) {
                    callback.onSuccess(result);
                }

                @Override
                public void onFailure(Throwable t) {
                    callback.onFailure(t);
                }
            }, MoreExecutors.directExecutor());
        }

        @Override
        public com.google.common.util.concurrent.ListenableFuture getWrappedFuture() {
            return (com.google.common.util.concurrent.ListenableFuture) super.getWrappedFuture();
        }
    }

    private static class GuavaListenableWrappingSpringListenableFuture extends FutureWrapper implements com.google.common.util.concurrent.ListenableFuture {

        public GuavaListenableWrappingSpringListenableFuture(ListenableFuture springListenableFuture) {
            super(springListenableFuture);
        }

        @Override
        public void addListener(final Runnable command, final Executor executor) {
            getWrappedFuture().addCallback(new ListenableFutureCallback() {
                @Override
                public void onSuccess(T result) {
                    executor.execute(command);
                }

                @Override
                public void onFailure(Throwable t) {
                    executor.execute(command);
                }
            });
        }

        @Override
        public ListenableFuture getWrappedFuture() {
            return (ListenableFuture) super.getWrappedFuture();
        }
    }
}