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.Iterator;

import org.reactivestreams.*;

import io.reactivex.*;
import io.reactivex.exceptions.Exceptions;
import io.reactivex.functions.BiFunction;
import io.reactivex.internal.functions.ObjectHelper;
import io.reactivex.internal.subscriptions.*;
import io.reactivex.plugins.RxJavaPlugins;

public final class FlowableZipIterable<T, U, V> extends AbstractFlowableWithUpstream<T, V> {
    final Iterable<U> other;
    final BiFunction<? super T, ? super U, ? extends V> zipper;

    public FlowableZipIterable(
            Flowable<T> source,
            Iterable<U> other, BiFunction<? super T, ? super U, ? extends V> zipper) {
        super(source);
        this.other = other;
        this.zipper = zipper;
    }

    @Override
    public void subscribeActual(Subscriber<? super V> t) {
        Iterator<U> it;

        try {
            it = ObjectHelper.requireNonNull(other.iterator(), "The iterator returned by other is null");
        } catch (Throwable e) {
            Exceptions.throwIfFatal(e);
            EmptySubscription.error(e, t);
            return;
        }

        boolean b;

        try {
            b = it.hasNext();
        } catch (Throwable e) {
            Exceptions.throwIfFatal(e);
            EmptySubscription.error(e, t);
            return;
        }

        if (!b) {
            EmptySubscription.complete(t);
            return;
        }

        source.subscribe(new ZipIterableSubscriber<T, U, V>(t, it, zipper));
    }

    static final class ZipIterableSubscriber<T, U, V> implements FlowableSubscriber<T>, Subscription {
        final Subscriber<? super V> downstream;
        final Iterator<U> iterator;
        final BiFunction<? super T, ? super U, ? extends V> zipper;

        Subscription upstream;

        boolean done;

        ZipIterableSubscriber(Subscriber<? super V> actual, Iterator<U> iterator,
                BiFunction<? super T, ? super U, ? extends V> zipper) {
            this.downstream = actual;
            this.iterator = iterator;
            this.zipper = zipper;
        }

        @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;
            }

            U u;

            try {
                u = ObjectHelper.requireNonNull(iterator.next(), "The iterator returned a null value");
            } catch (Throwable e) {
                error(e);
                return;
            }

            V v;
            try {
                v = ObjectHelper.requireNonNull(zipper.apply(t, u), "The zipper function returned a null value");
            } catch (Throwable e) {
                error(e);
                return;
            }

            downstream.onNext(v);

            boolean b;

            try {
                b = iterator.hasNext();
            } catch (Throwable e) {
                error(e);
                return;
            }

            if (!b) {
                done = true;
                upstream.cancel();
                downstream.onComplete();
            }
        }

        void error(Throwable e) {
            Exceptions.throwIfFatal(e);
            done = true;
            upstream.cancel();
            downstream.onError(e);
        }

        @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;
            downstream.onComplete();
        }

        @Override
        public void request(long n) {
            upstream.request(n);
        }

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

    }
}