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/**
 * Copyright (c) 2016-present, RxJava Contributors.
 *
 * 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 io.reactivex.observable.internal.operators;

import java.util.concurrent.atomic.*;

import io.reactivex.common.*;
import io.reactivex.common.internal.disposables.DisposableHelper;
import io.reactivex.observable.*;
import io.reactivex.observable.internal.observers.QueueDrainObserver;
import io.reactivex.observable.internal.queues.MpscLinkedQueue;
import io.reactivex.observable.internal.utils.NotificationLite;
import io.reactivex.observable.observers.*;
import io.reactivex.observable.subjects.UnicastSubject;

public final class ObservableWindowBoundary extends AbstractObservableWithUpstream> {
    final ObservableSource other;
    final int bufferSize;

    public ObservableWindowBoundary(ObservableSource source, ObservableSource other, int bufferSize) {
        super(source);
        this.other = other;
        this.bufferSize = bufferSize;
    }

    @Override
    public void subscribeActual(Observer> t) {
        source.subscribe(new WindowBoundaryMainObserver(new SerializedObserver>(t), other, bufferSize));
    }

    static final class WindowBoundaryMainObserver
    extends QueueDrainObserver>
    implements Disposable {

        final ObservableSource other;
        final int bufferSize;

        Disposable s;

        final AtomicReference boundary = new AtomicReference();

        UnicastSubject window;

        static final Object NEXT = new Object();

        final AtomicLong windows = new AtomicLong();

        WindowBoundaryMainObserver(Observer> actual, ObservableSource other,
                int bufferSize) {
            super(actual, new MpscLinkedQueue());
            this.other = other;
            this.bufferSize = bufferSize;
            windows.lazySet(1);
        }

        @Override
        public void onSubscribe(Disposable s) {
            if (DisposableHelper.validate(this.s, s)) {
                this.s = s;

                Observer> a = actual;
                a.onSubscribe(this);

                if (cancelled) {
                    return;
                }

                UnicastSubject w = UnicastSubject.create(bufferSize);

                window = w;

                a.onNext(w);

                WindowBoundaryInnerObserver inner = new WindowBoundaryInnerObserver(this);

                if (boundary.compareAndSet(null, inner)) {
                    windows.getAndIncrement();
                    other.subscribe(inner);
                }
            }
        }

        @Override
        public void onNext(T t) {
            if (fastEnter()) {
                UnicastSubject w = window;

                w.onNext(t);

                if (leave(-1) == 0) {
                    return;
                }
            } else {
                queue.offer(NotificationLite.next(t));
                if (!enter()) {
                    return;
                }
            }
            drainLoop();
        }

        @Override
        public void onError(Throwable t) {
            if (done) {
                RxJavaCommonPlugins.onError(t);
                return;
            }
            error = t;
            done = true;
            if (enter()) {
                drainLoop();
            }

            if (windows.decrementAndGet() == 0) {
                DisposableHelper.dispose(boundary);
            }

            actual.onError(t);
        }

        @Override
        public void onComplete() {
            if (done) {
                return;
            }
            done = true;
            if (enter()) {
                drainLoop();
            }

            if (windows.decrementAndGet() == 0) {
                DisposableHelper.dispose(boundary);
            }

            actual.onComplete();

        }

        @Override
        public void dispose() {
            cancelled = true;
        }

        @Override
        public boolean isDisposed() {
            return cancelled;
        }

        void drainLoop() {
            final MpscLinkedQueue q = (MpscLinkedQueue)queue;
            final Observer> a = actual;
            int missed = 1;
            UnicastSubject w = window;
            for (;;) {

                for (;;) {
                    boolean d = done;

                    Object o = q.poll();

                    boolean empty = o == null;

                    if (d && empty) {
                        DisposableHelper.dispose(boundary);
                        Throwable e = error;
                        if (e != null) {
                            w.onError(e);
                        } else {
                            w.onComplete();
                        }
                        return;
                    }

                    if (empty) {
                        break;
                    }

                    if (o == NEXT) {
                        w.onComplete();

                        if (windows.decrementAndGet() == 0) {
                            DisposableHelper.dispose(boundary);
                            return;
                        }

                        if (cancelled) {
                            continue;
                        }

                        w = UnicastSubject.create(bufferSize);

                        windows.getAndIncrement();

                        window = w;

                        a.onNext(w);

                        continue;
                    }

                    w.onNext(NotificationLite.getValue(o));
                }

                missed = leave(-missed);
                if (missed == 0) {
                    return;
                }
            }
        }

        void next() {
            queue.offer(NEXT);
            if (enter()) {
                drainLoop();
            }
        }
    }

    static final class WindowBoundaryInnerObserver extends DisposableObserver {
        final WindowBoundaryMainObserver parent;

        boolean done;

        WindowBoundaryInnerObserver(WindowBoundaryMainObserver parent) {
            this.parent = parent;
        }

        @Override
        public void onNext(B t) {
            if (done) {
                return;
            }
            parent.next();
        }

        @Override
        public void onError(Throwable t) {
            if (done) {
                RxJavaCommonPlugins.onError(t);
                return;
            }
            done = true;
            parent.onError(t);
        }

        @Override
        public void onComplete() {
            if (done) {
                return;
            }
            done = true;
            parent.onComplete();
        }
    }
}