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/**
 * Copyright 2009-2016 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.springcommon;

import net.javacrumbs.futureconverter.common.internal.FutureWrapper;
import net.javacrumbs.futureconverter.common.internal.ValueSource;
import net.javacrumbs.futureconverter.common.internal.ValueSourceFuture;
import org.springframework.util.concurrent.FailureCallback;
import org.springframework.util.concurrent.ListenableFuture;
import org.springframework.util.concurrent.ListenableFutureCallback;
import org.springframework.util.concurrent.SettableListenableFuture;
import org.springframework.util.concurrent.SuccessCallback;

import java.util.function.Consumer;


public class SpringFutureUtils {
    // *************************************** Converting to ListenableFuture ******************************************

    public static  ListenableFuture createListenableFuture(ValueSourceFuture valueSource) {
        if (valueSource instanceof ListenableFutureBackedValueSourceFuture) {
            return ((ListenableFutureBackedValueSourceFuture) valueSource).getWrappedFuture();
        } else {
            return new ValueSourceFutureBackedListenableFuture<>(valueSource);
        }
    }

    public static  ListenableFuture createListenableFuture(ValueSource valueSource) {
        if (valueSource instanceof ListenableFutureBackedValueSourceFuture) {
            return ((ListenableFutureBackedValueSourceFuture) valueSource).getWrappedFuture();
        } else {
            return new ValueSourceBackedListenableFuture<>(valueSource);
        }
    }

    /**
     * ListenableFuture that delegates all the work to ValueSourceFuture.
     */
    private static class ValueSourceFutureBackedListenableFuture extends FutureWrapper implements ListenableFuture {
        private ValueSourceFutureBackedListenableFuture(ValueSourceFuture valueSourceFuture) {
            super(valueSourceFuture);
        }

        @Override
        public void addCallback(ListenableFutureCallback callback) {
            getWrappedFuture().addCallbacks(callback::onSuccess, callback::onFailure);
        }

        @Override
        public void addCallback(SuccessCallback successCallback, FailureCallback failureCallback) {
            getWrappedFuture().addCallbacks(successCallback::onSuccess, failureCallback::onFailure);
        }

        @Override
        protected ValueSourceFuture getWrappedFuture() {
            return (ValueSourceFuture) super.getWrappedFuture();
        }
    }


    /**
     * If we only get ValueSource we have to create a ValueSourceFuture. Here we wrap Spring SettableListenableFuture
     * and use it for listener handling and value storage.
     */
    private static class ValueSourceBackedListenableFuture extends FutureWrapper implements ListenableFuture {
        private final ValueSource valueSource;

        private ValueSourceBackedListenableFuture(ValueSource valueSource) {
            super(new SettableListenableFuture<>());
            this.valueSource = valueSource;
            valueSource.addCallbacks(value -> getWrappedFuture().set(value), ex -> getWrappedFuture().setException(ex));
        }


        @Override
        protected SettableListenableFuture getWrappedFuture() {
            return (SettableListenableFuture) super.getWrappedFuture();
        }

        @Override
        public boolean cancel(boolean mayInterruptIfRunning) {
            valueSource.cancel(mayInterruptIfRunning);
            return super.cancel(mayInterruptIfRunning);
        }

        private ValueSource getValueSource() {
            return valueSource;
        }

        @Override
        public void addCallback(ListenableFutureCallback callback) {
            getWrappedFuture().addCallback(callback);
        }

        @Override
        public void addCallback(SuccessCallback successCallback, FailureCallback failureCallback) {
            getWrappedFuture().addCallback(successCallback, failureCallback);
        }
    }

    // *************************************** Converting from ListenableFuture ******************************************

    public static  ValueSourceFuture createValueSourceFuture(ListenableFuture listenableFuture) {
        if (listenableFuture instanceof ValueSourceFutureBackedListenableFuture) {
            return ((ValueSourceFutureBackedListenableFuture) listenableFuture).getWrappedFuture();
        } else {
            return new ListenableFutureBackedValueSourceFuture<>(listenableFuture);
        }
    }

    public static  ValueSource createValueSource(ListenableFuture listenableFuture) {
        if (listenableFuture instanceof ValueSourceBackedListenableFuture) {
            return ((ValueSourceBackedListenableFuture) listenableFuture).getValueSource();
        } else {
            return new ListenableFutureBackedValueSourceFuture<>(listenableFuture);
        }
    }


    private static class ListenableFutureBackedValueSourceFuture extends ValueSourceFuture {
        private ListenableFutureBackedValueSourceFuture(ListenableFuture wrappedFuture) {
            super(wrappedFuture);
        }

        @Override
        public void addCallbacks(Consumer successCallback, Consumer failureCallback) {
            getWrappedFuture().addCallback(successCallback::accept, failureCallback::accept);
        }

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