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.
/**
 * 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.internal.operators.flowable;

import java.util.*;
import java.util.concurrent.Callable;
import java.util.concurrent.atomic.*;

import org.reactivestreams.*;

import io.reactivex.*;
import io.reactivex.exceptions.Exceptions;
import io.reactivex.functions.BooleanSupplier;
import io.reactivex.internal.functions.ObjectHelper;
import io.reactivex.internal.subscriptions.SubscriptionHelper;
import io.reactivex.internal.util.*;
import io.reactivex.plugins.RxJavaPlugins;

public final class FlowableBuffer<T, C extends Collection<? super T>> extends AbstractFlowableWithUpstream<T, C> {
    final int size;

    final int skip;

    final Callable<C> bufferSupplier;

    public FlowableBuffer(Flowable<T> source, int size, int skip, Callable<C> bufferSupplier) {
        super(source);
        this.size = size;
        this.skip = skip;
        this.bufferSupplier = bufferSupplier;
    }

    @Override
    public void subscribeActual(Subscriber<? super C> s) {
        if (size == skip) {
            source.subscribe(new PublisherBufferExactSubscriber<T, C>(s, size, bufferSupplier));
        } else if (skip > size) {
            source.subscribe(new PublisherBufferSkipSubscriber<T, C>(s, size, skip, bufferSupplier));
        } else {
            source.subscribe(new PublisherBufferOverlappingSubscriber<T, C>(s, size, skip, bufferSupplier));
        }
    }

    static final class PublisherBufferExactSubscriber<T, C extends Collection<? super T>>
      implements FlowableSubscriber<T>, Subscription {

        final Subscriber<? super C> downstream;

        final Callable<C> bufferSupplier;

        final int size;

        C buffer;

        Subscription upstream;

        boolean done;

        int index;

        PublisherBufferExactSubscriber(Subscriber<? super C> actual, int size, Callable<C> bufferSupplier) {
            this.downstream = actual;
            this.size = size;
            this.bufferSupplier = bufferSupplier;
        }

        @Override
        public void request(long n) {
            if (SubscriptionHelper.validate(n)) {
                upstream.request(BackpressureHelper.multiplyCap(n, size));
            }
        }

        @Override
        public void cancel() {
            upstream.cancel();
        }

        @Override
        public void onSubscribe(Subscription s) {
            if (SubscriptionHelper.validate(this.upstream, s)) {
                this.upstream = s;

                downstream.onSubscribe(this);
            }
        }

        @Override
        public void onNext(T t) {
            if (done) {
                return;
            }

            C b = buffer;
            if (b == null) {

                try {
                    b = ObjectHelper.requireNonNull(bufferSupplier.call(), "The bufferSupplier returned a null buffer");
                } catch (Throwable e) {
                    Exceptions.throwIfFatal(e);
                    cancel();
                    onError(e);
                    return;
                }

                buffer = b;
            }

            b.add(t);

            int i = index + 1;
            if (i == size) {
                index = 0;
                buffer = null;
                downstream.onNext(b);
            } else {
                index = i;
            }
        }

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

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

            C b = buffer;

            if (b != null && !b.isEmpty()) {
                downstream.onNext(b);
            }
            downstream.onComplete();
        }
    }

    static final class PublisherBufferSkipSubscriber<T, C extends Collection<? super T>>
    extends AtomicInteger
    implements FlowableSubscriber<T>, Subscription {

        private static final long serialVersionUID = -5616169793639412593L;

        final Subscriber<? super C> downstream;

        final Callable<C> bufferSupplier;

        final int size;

        final int skip;

        C buffer;

        Subscription upstream;

        boolean done;

        int index;

        PublisherBufferSkipSubscriber(Subscriber<? super C> actual, int size, int skip,
                Callable<C> bufferSupplier) {
            this.downstream = actual;
            this.size = size;
            this.skip = skip;
            this.bufferSupplier = bufferSupplier;
        }

        @Override
        public void request(long n) {
            if (SubscriptionHelper.validate(n)) {
                if (get() == 0 && compareAndSet(0, 1)) {
                    // n full buffers
                    long u = BackpressureHelper.multiplyCap(n, size);
                    // + (n - 1) gaps
                    long v = BackpressureHelper.multiplyCap(skip - size, n - 1);

                    upstream.request(BackpressureHelper.addCap(u, v));
                } else {
                    // n full buffer + gap
                    upstream.request(BackpressureHelper.multiplyCap(skip, n));
                }
            }
        }

        @Override
        public void cancel() {
            upstream.cancel();
        }

        @Override
        public void onSubscribe(Subscription s) {
            if (SubscriptionHelper.validate(this.upstream, s)) {
                this.upstream = s;

                downstream.onSubscribe(this);
            }
        }

        @Override
        public void onNext(T t) {
            if (done) {
                return;
            }

            C b = buffer;

            int i = index;

            if (i++ == 0) {
                try {
                    b = ObjectHelper.requireNonNull(bufferSupplier.call(), "The bufferSupplier returned a null buffer");
                } catch (Throwable e) {
                    Exceptions.throwIfFatal(e);
                    cancel();

                    onError(e);
                    return;
                }

                buffer = b;
            }

            if (b != null) {
                b.add(t);
                if (b.size() == size) {
                    buffer = null;
                    downstream.onNext(b);
                }
            }

            if (i == skip) {
                i = 0;
            }
            index = i;
        }

        @Override
        public void onError(Throwable t) {
            if (done) {
                RxJavaPlugins.onError(t);
                return;
            }

            done = true;
            buffer = null;

            downstream.onError(t);
        }

        @Override
        public void onComplete() {
            if (done) {
                return;
            }

            done = true;
            C b = buffer;
            buffer = null;

            if (b != null) {
                downstream.onNext(b);
            }

            downstream.onComplete();
        }
    }

    static final class PublisherBufferOverlappingSubscriber<T, C extends Collection<? super T>>
    extends AtomicLong
    implements FlowableSubscriber<T>, Subscription, BooleanSupplier {

        private static final long serialVersionUID = -7370244972039324525L;

        final Subscriber<? super C> downstream;

        final Callable<C> bufferSupplier;

        final int size;

        final int skip;

        final ArrayDeque<C> buffers;

        final AtomicBoolean once;

        Subscription upstream;

        boolean done;

        int index;

        volatile boolean cancelled;

        long produced;

        PublisherBufferOverlappingSubscriber(Subscriber<? super C> actual, int size, int skip,
                Callable<C> bufferSupplier) {
            this.downstream = actual;
            this.size = size;
            this.skip = skip;
            this.bufferSupplier = bufferSupplier;
            this.once = new AtomicBoolean();
            this.buffers = new ArrayDeque<C>();
        }

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

        @Override
        public void request(long n) {
            if (SubscriptionHelper.validate(n)) {
                if (QueueDrainHelper.postCompleteRequest(n, downstream, buffers, this, this)) {
                    return;
                }

                if (!once.get() && once.compareAndSet(false, true)) {
                    // (n - 1) skips
                    long u = BackpressureHelper.multiplyCap(skip, n - 1);

                    // + 1 full buffer
                    long r = BackpressureHelper.addCap(size, u);
                    upstream.request(r);
                } else {
                    // n skips
                    long r = BackpressureHelper.multiplyCap(skip, n);
                    upstream.request(r);
                }
            }
        }

        @Override
        public void cancel() {
            cancelled = true;
            upstream.cancel();
        }

        @Override
        public void onSubscribe(Subscription s) {
            if (SubscriptionHelper.validate(this.upstream, s)) {
                this.upstream = s;

                downstream.onSubscribe(this);
            }
        }

        @Override
        public void onNext(T t) {
            if (done) {
                return;
            }

            ArrayDeque<C> bs = buffers;

            int i = index;

            if (i++ == 0) {
                C b;

                try {
                    b = ObjectHelper.requireNonNull(bufferSupplier.call(), "The bufferSupplier returned a null buffer");
                } catch (Throwable e) {
                    Exceptions.throwIfFatal(e);
                    cancel();
                    onError(e);
                    return;
                }

                bs.offer(b);
            }

            C b = bs.peek();

            if (b != null && b.size() + 1 == size) {
                bs.poll();

                b.add(t);

                produced++;

                downstream.onNext(b);
            }

            for (C b0 : bs) {
                b0.add(t);
            }

            if (i == skip) {
                i = 0;
            }
            index = i;
        }

        @Override
        public void onError(Throwable t) {
            if (done) {
                RxJavaPlugins.onError(t);
                return;
            }

            done = true;
            buffers.clear();

            downstream.onError(t);
        }

        @Override
        public void onComplete() {
            if (done) {
                return;
            }

            done = true;

            long p = produced;
            if (p != 0L) {
                BackpressureHelper.produced(this, p);
            }
            QueueDrainHelper.postComplete(downstream, buffers, this, this);
        }
    }
}