code: /*
   * 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.rxjava3.internal.operators.flowable;
  
  import java.util.ArrayDeque;
  import java.util.concurrent.atomic.*;
  
  import org.reactivestreams.*;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.internal.subscriptions.SubscriptionHelper;
  import io.reactivex.rxjava3.internal.util.BackpressureHelper;
  import io.reactivex.rxjava3.operators.SpscLinkedArrayQueue;
  import io.reactivex.rxjava3.processors.UnicastProcessor;
  
  public final class FlowableWindow<T> extends AbstractFlowableWithUpstream<T, Flowable<T>> {
      final long size;
  
      final long skip;
  
      final int bufferSize;
  
      public FlowableWindow(Flowable<T> source, long size, long skip,  int bufferSize) {
          super(source);
          this.size = size;
          this.skip = skip;
          this.bufferSize = bufferSize;
      }
  
      @Override
      public void subscribeActual(Subscriber<? super Flowable<T>> s) {
          if (skip == size) {
              source.subscribe(new WindowExactSubscriber<>(s, size, bufferSize));
          } else
          if (skip > size) {
              source.subscribe(new WindowSkipSubscriber<>(s, size, skip, bufferSize));
          } else {
              source.subscribe(new WindowOverlapSubscriber<>(s, size, skip, bufferSize));
          }
      }
  
      static final class WindowExactSubscriber<T>
      extends AtomicInteger
      implements FlowableSubscriber<T>, Subscription, Runnable {
  
          private static final long serialVersionUID = -2365647875069161133L;
  
          final Subscriber<? super Flowable<T>> downstream;
  
          final long size;
  
          final AtomicBoolean once;
  
          final int bufferSize;
  
          long index;
  
          Subscription upstream;
  
          UnicastProcessor<T> window;
  
          WindowExactSubscriber(Subscriber<? super Flowable<T>> actual, long size, int bufferSize) {
              super(1);
              this.downstream = actual;
              this.size = size;
              this.once = new AtomicBoolean();
              this.bufferSize = bufferSize;
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              if (SubscriptionHelper.validate(this.upstream, s)) {
                  this.upstream = s;
                  downstream.onSubscribe(this);
              }
          }
  
          @Override
          public void onNext(T t) {
              long i = index;
  
              UnicastProcessor<T> w = window;
              FlowableWindowSubscribeIntercept<T> intercept = null;
              if (i == 0) {
                  getAndIncrement();
  
                  w = UnicastProcessor.create(bufferSize, this);
                  window = w;
  
                  intercept = new FlowableWindowSubscribeIntercept<>(w);
                  downstream.onNext(intercept);
              }
  
              i++;
  
              w.onNext(t);
  
              if (i == size) {
                  index = 0;
                  window = null;
                  w.onComplete();
              } else {
                  index = i;
              }
  
              if (intercept != null && intercept.tryAbandon()) {
                  intercept.window.onComplete();
              }
          }
  
          @Override
          public void onError(Throwable t) {
              Processor<T, T> w = window;
              if (w != null) {
                  window = null;
                  w.onError(t);
              }
  
              downstream.onError(t);
          }
  
          @Override
          public void onComplete() {
              Processor<T, T> w = window;
              if (w != null) {
                  window = null;
                  w.onComplete();
              }
  
              downstream.onComplete();
          }
  
          @Override
          public void request(long n) {
              if (SubscriptionHelper.validate(n)) {
                  long u = BackpressureHelper.multiplyCap(size, n);
                  upstream.request(u);
              }
          }
  
          @Override
          public void cancel() {
              if (once.compareAndSet(false, true)) {
                  run();
              }
          }
  
          @Override
          public void run() {
              if (decrementAndGet() == 0) {
                  upstream.cancel();
              }
          }
      }
  
      static final class WindowSkipSubscriber<T>
      extends AtomicInteger
      implements FlowableSubscriber<T>, Subscription, Runnable {
  
          private static final long serialVersionUID = -8792836352386833856L;
  
          final Subscriber<? super Flowable<T>> downstream;
  
          final long size;
  
          final long skip;
  
          final AtomicBoolean once;
  
          final AtomicBoolean firstRequest;
  
          final int bufferSize;
  
          long index;
  
          Subscription upstream;
  
          UnicastProcessor<T> window;
  
          WindowSkipSubscriber(Subscriber<? super Flowable<T>> actual, long size, long skip, int bufferSize) {
              super(1);
              this.downstream = actual;
              this.size = size;
              this.skip = skip;
              this.once = new AtomicBoolean();
              this.firstRequest = new AtomicBoolean();
              this.bufferSize = bufferSize;
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              if (SubscriptionHelper.validate(this.upstream, s)) {
                  this.upstream = s;
                  downstream.onSubscribe(this);
              }
          }
  
          @Override
          public void onNext(T t) {
              long i = index;
  
              FlowableWindowSubscribeIntercept<T> intercept = null;
              UnicastProcessor<T> w = window;
              if (i == 0) {
                  getAndIncrement();
  
                  w = UnicastProcessor.create(bufferSize, this);
                  window = w;
  
                  intercept = new FlowableWindowSubscribeIntercept<>(w);
                  downstream.onNext(intercept);
              }
  
              i++;
  
              if (w != null) {
                  w.onNext(t);
              }
  
              if (i == size) {
                  window = null;
                  w.onComplete();
              }
  
              if (i == skip) {
                  index = 0;
              } else {
                  index = i;
              }
  
              if (intercept != null && intercept.tryAbandon()) {
                  intercept.window.onComplete();
              }
          }
  
          @Override
          public void onError(Throwable t) {
              Processor<T, T> w = window;
              if (w != null) {
                  window = null;
                  w.onError(t);
              }
  
              downstream.onError(t);
          }
  
          @Override
          public void onComplete() {
              Processor<T, T> w = window;
              if (w != null) {
                  window = null;
                  w.onComplete();
              }
  
              downstream.onComplete();
          }
  
          @Override
          public void request(long n) {
              if (SubscriptionHelper.validate(n)) {
                  if (!firstRequest.get() && firstRequest.compareAndSet(false, true)) {
                      long u = BackpressureHelper.multiplyCap(size, n);
                      long v = BackpressureHelper.multiplyCap(skip - size, n - 1);
                      long w = BackpressureHelper.addCap(u, v);
                      upstream.request(w);
                  } else {
                      long u = BackpressureHelper.multiplyCap(skip, n);
                      upstream.request(u);
                  }
              }
          }
  
          @Override
          public void cancel() {
              if (once.compareAndSet(false, true)) {
                  run();
              }
          }
  
          @Override
          public void run() {
              if (decrementAndGet() == 0) {
                  upstream.cancel();
              }
          }
      }
  
      static final class WindowOverlapSubscriber<T>
      extends AtomicInteger
      implements FlowableSubscriber<T>, Subscription, Runnable {
  
          private static final long serialVersionUID = 2428527070996323976L;
  
          final Subscriber<? super Flowable<T>> downstream;
  
          final SpscLinkedArrayQueue<UnicastProcessor<T>> queue;
  
          final long size;
  
          final long skip;
  
          final ArrayDeque<UnicastProcessor<T>> windows;
  
          final AtomicBoolean once;
  
          final AtomicBoolean firstRequest;
  
          final AtomicLong requested;
  
          final AtomicInteger wip;
  
          final int bufferSize;
  
          long index;
  
          long produced;
  
          Subscription upstream;
  
          volatile boolean done;
          Throwable error;
  
          volatile boolean cancelled;
  
          WindowOverlapSubscriber(Subscriber<? super Flowable<T>> actual, long size, long skip, int bufferSize) {
              super(1);
              this.downstream = actual;
              this.size = size;
              this.skip = skip;
              this.queue = new SpscLinkedArrayQueue<>(bufferSize);
              this.windows = new ArrayDeque<>();
              this.once = new AtomicBoolean();
              this.firstRequest = new AtomicBoolean();
              this.requested = new AtomicLong();
              this.wip = new AtomicInteger();
              this.bufferSize = bufferSize;
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              if (SubscriptionHelper.validate(this.upstream, s)) {
                  this.upstream = s;
                  downstream.onSubscribe(this);
              }
          }
  
          @Override
          public void onNext(T t) {
              long i = index;
  
              UnicastProcessor<T> newWindow = null;
              if (i == 0) {
                  if (!cancelled) {
                      getAndIncrement();
  
                      newWindow = UnicastProcessor.create(bufferSize, this);
  
                      windows.offer(newWindow);
                  }
              }
  
              i++;
  
              for (Processor<T, T> w : windows) {
                  w.onNext(t);
              }
  
              if (newWindow != null) {
                  queue.offer(newWindow);
                  drain();
              }
  
              long p = produced + 1;
              if (p == size) {
                  produced = p - skip;
  
                  Processor<T, T> w = windows.poll();
                  if (w != null) {
                      w.onComplete();
                  }
              } else {
                  produced = p;
              }
  
              if (i == skip) {
                  index = 0;
              } else {
                  index = i;
              }
          }
  
          @Override
          public void onError(Throwable t) {
              for (Processor<T, T> w : windows) {
                  w.onError(t);
              }
              windows.clear();
  
              error = t;
              done = true;
              drain();
          }
  
          @Override
          public void onComplete() {
              for (Processor<T, T> w : windows) {
                  w.onComplete();
              }
              windows.clear();
  
              done = true;
              drain();
          }
  
          void drain() {
              if (wip.getAndIncrement() != 0) {
                  return;
              }
  
              final Subscriber<? super Flowable<T>> a = downstream;
              final SpscLinkedArrayQueue<UnicastProcessor<T>> q = queue;
              int missed = 1;
  
              outer:
              for (;;) {
  
                  if (cancelled) {
                      UnicastProcessor<T> up = null;
                      while ((up = q.poll()) != null) {
                          up.onComplete();
                      }
                  } else {
                      long r = requested.get();
                      long e = 0;
  
                      while (e != r) {
                          boolean d = done;
  
                          UnicastProcessor<T> t = q.poll();
  
                          boolean empty = t == null;
  
                          if (cancelled) {
                              continue outer;
                          }
  
                          if (checkTerminated(d, empty, a, q)) {
                              return;
                          }
  
                          if (empty) {
                              break;
                          }
  
                          FlowableWindowSubscribeIntercept<T> intercept = new FlowableWindowSubscribeIntercept<>(t);
                          a.onNext(intercept);
  
                          if (intercept.tryAbandon()) {
                              t.onComplete();
                          }
                          e++;
                      }
  
                      if (e == r) {
                          if (cancelled) {
                              continue;
                          }
  
                          if (checkTerminated(done, q.isEmpty(), a, q)) {
                              return;
                          }
                      }
  
                      if (e != 0L && r != Long.MAX_VALUE) {
                          requested.addAndGet(-e);
                      }
                  }
  
                  missed = wip.addAndGet(-missed);
                  if (missed == 0) {
                      break;
                  }
              }
          }
  
          boolean checkTerminated(boolean d, boolean empty, Subscriber<?> a, SpscLinkedArrayQueue<?> q) {
              if (d) {
                  Throwable e = error;
  
                  if (e != null) {
                      q.clear();
                      a.onError(e);
                      return true;
                  } else
                  if (empty) {
                      a.onComplete();
                      return true;
                  }
              }
  
              return false;
          }
  
          @Override
          public void request(long n) {
              if (SubscriptionHelper.validate(n)) {
                  BackpressureHelper.add(requested, n);
  
                  if (!firstRequest.get() && firstRequest.compareAndSet(false, true)) {
                      long u = BackpressureHelper.multiplyCap(skip, n - 1);
                      long v = BackpressureHelper.addCap(size, u);
                      upstream.request(v);
                  } else {
                      long u = BackpressureHelper.multiplyCap(skip, n);
                      upstream.request(u);
                  }
  
                  drain();
              }
          }
  
          @Override
          public void cancel() {
              cancelled = true;
              if (once.compareAndSet(false, true)) {
                  run();
              }
              drain();
          }
  
          @Override
          public void run() {
              if (decrementAndGet() == 0) {
                  upstream.cancel();
              }
          }
      }
  }
  