/*

 * Copyright (c) 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.  Oracle designates this

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

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.incubator.http;

import java.util.concurrent.Flow;

import java.util.concurrent.atomic.AtomicBoolean;

// Completes the subscription on first request. Never calls onNext()

class PseudoPublisher<T> implements Flow.Publisher<T> {

    private final Throwable throwable;

    PseudoPublisher() {

        this(null);

    }

    PseudoPublisher(Throwable throwable) {

        this.throwable = throwable;

    }

    @Override

    public void subscribe(Flow.Subscriber<? super T> subscriber) {

        subscriber.onSubscribe(new Subscription(subscriber));

    }

    private class Subscription implements Flow.Subscription {

        private final Flow.Subscriber<? super T> subscriber;

        private final AtomicBoolean done = new AtomicBoolean();

        Subscription(Flow.Subscriber<? super T> subscriber) {

            this.subscriber = subscriber;

        }

        @Override

        public void request(long n) {

            if (done.compareAndSet(false, true)) {

                if (n > 0) {

                    if (throwable == null) {

                        subscriber.onComplete();

                    } else {

                        subscriber.onError(throwable);

                    }

                } else {

                    subscriber.onError(new IllegalArgumentException("request(" + n + ")"));

                }

            }

        }

        @Override

        public void cancel() {

            done.set(true);

        }

    }

}