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.concurrent.atomic.AtomicBoolean;

import org.reactivestreams.*;

import io.reactivex.*;
import io.reactivex.internal.subscriptions.*;
import io.reactivex.plugins.RxJavaPlugins;

public final class FlowableTake<T> extends AbstractFlowableWithUpstream<T, T> {
    final long limit;
    public FlowableTake(Flowable<T> source, long limit) {
        super(source);
        this.limit = limit;
    }

    @Override
    protected void subscribeActual(Subscriber<? super T> s) {
        source.subscribe(new TakeSubscriber<T>(s, limit));
    }

    static final class TakeSubscriber<T> extends AtomicBoolean implements FlowableSubscriber<T>, Subscription {

        private static final long serialVersionUID = -5636543848937116287L;

        final Subscriber<? super T> downstream;

        final long limit;

        boolean done;

        Subscription upstream;

        long remaining;

        TakeSubscriber(Subscriber<? super T> actual, long limit) {
            this.downstream = actual;
            this.limit = limit;
            this.remaining = limit;
        }

        @Override
        public void onSubscribe(Subscription s) {
            if (SubscriptionHelper.validate(this.upstream, s)) {
                upstream = s;
                if (limit == 0L) {
                    s.cancel();
                    done = true;
                    EmptySubscription.complete(downstream);
                } else {
                    downstream.onSubscribe(this);
                }
            }
        }

        @Override
        public void onNext(T t) {
            if (!done && remaining-- > 0) {
                boolean stop = remaining == 0;
                downstream.onNext(t);
                if (stop) {
                    upstream.cancel();
                    onComplete();
                }
            }
        }

        @Override
        public void onError(Throwable t) {
            if (!done) {
                done = true;
                upstream.cancel();
                downstream.onError(t);
            } else {
                RxJavaPlugins.onError(t);
            }
        }

        @Override
        public void onComplete() {
            if (!done) {
                done = true;
                downstream.onComplete();
            }
        }

        @Override
        public void request(long n) {
            if (!SubscriptionHelper.validate(n)) {
                return;
            }
            if (!get() && compareAndSet(false, true)) {
                if (n >= limit) {
                    upstream.request(Long.MAX_VALUE);
                    return;
                }
            }
            upstream.request(n);
        }

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