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.parallel;

import org.reactivestreams.*;

import io.reactivex.FlowableSubscriber;
import io.reactivex.exceptions.Exceptions;
import io.reactivex.functions.Function;
import io.reactivex.internal.functions.ObjectHelper;
import io.reactivex.internal.fuseable.ConditionalSubscriber;
import io.reactivex.internal.subscriptions.SubscriptionHelper;
import io.reactivex.parallel.ParallelFlowable;
import io.reactivex.plugins.RxJavaPlugins;

Maps each 'rail' of the source ParallelFlowable with a mapper function.
Type parameters:
<T> – the input value type
<R> – the output value type/**
 * Maps each 'rail' of the source ParallelFlowable with a mapper function.
 *
 * @param <T> the input value type
 * @param <R> the output value type
 */
public final class ParallelMap<T, R> extends ParallelFlowable<R> {

    final ParallelFlowable<T> source;

    final Function<? super T, ? extends R> mapper;

    public ParallelMap(ParallelFlowable<T> source, Function<? super T, ? extends R> mapper) {
        this.source = source;
        this.mapper = mapper;
    }

    @Override
    public void subscribe(Subscriber<? super R>[] subscribers) {
        if (!validate(subscribers)) {
            return;
        }

        int n = subscribers.length;
        @SuppressWarnings("unchecked")
        Subscriber<? super T>[] parents = new Subscriber[n];

        for (int i = 0; i < n; i++) {
            Subscriber<? super R> a = subscribers[i];
            if (a instanceof ConditionalSubscriber) {
                parents[i] = new ParallelMapConditionalSubscriber<T, R>((ConditionalSubscriber<? super R>)a, mapper);
            } else {
                parents[i] = new ParallelMapSubscriber<T, R>(a, mapper);
            }
        }

        source.subscribe(parents);
    }

    @Override
    public int parallelism() {
        return source.parallelism();
    }

    static final class ParallelMapSubscriber<T, R> implements FlowableSubscriber<T>, Subscription {

        final Subscriber<? super R> downstream;

        final Function<? super T, ? extends R> mapper;

        Subscription upstream;

        boolean done;

        ParallelMapSubscriber(Subscriber<? super R> actual, Function<? super T, ? extends R> mapper) {
            this.downstream = actual;
            this.mapper = mapper;
        }

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

            try {
                v = ObjectHelper.requireNonNull(mapper.apply(t), "The mapper returned a null value");
            } catch (Throwable ex) {
                Exceptions.throwIfFatal(ex);
                cancel();
                onError(ex);
                return;
            }

            downstream.onNext(v);
        }

        @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();
        }

    }
    static final class ParallelMapConditionalSubscriber<T, R> implements ConditionalSubscriber<T>, Subscription {

        final ConditionalSubscriber<? super R> downstream;

        final Function<? super T, ? extends R> mapper;

        Subscription upstream;

        boolean done;

        ParallelMapConditionalSubscriber(ConditionalSubscriber<? super R> actual, Function<? super T, ? extends R> mapper) {
            this.downstream = actual;
            this.mapper = mapper;
        }

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

            try {
                v = ObjectHelper.requireNonNull(mapper.apply(t), "The mapper returned a null value");
            } catch (Throwable ex) {
                Exceptions.throwIfFatal(ex);
                cancel();
                onError(ex);
                return;
            }

            downstream.onNext(v);
        }

        @Override
        public boolean tryOnNext(T t) {
            if (done) {
                return false;
            }
            R v;

            try {
                v = ObjectHelper.requireNonNull(mapper.apply(t), "The mapper returned a null value");
            } catch (Throwable ex) {
                Exceptions.throwIfFatal(ex);
                cancel();
                onError(ex);
                return false;
            }

            return downstream.tryOnNext(v);
        }

        @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();
        }

    }
}