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

Filters each 'rail' of the source ParallelFlowable with a predicate function.
Type parameters:
<T> – the input value type/**
 * Filters each 'rail' of the source ParallelFlowable with a predicate function.
 *
 * @param <T> the input value type
 */
public final class ParallelFilter<T> extends ParallelFlowable<T> {

    final ParallelFlowable<T> source;

    final Predicate<? super T> predicate;

    public ParallelFilter(ParallelFlowable<T> source, Predicate<? super T> predicate) {
        this.source = source;
        this.predicate = predicate;
    }

    @Override
    public void subscribe(Subscriber<? super T>[] 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 T> a = subscribers[i];
            if (a instanceof ConditionalSubscriber) {
                parents[i] = new ParallelFilterConditionalSubscriber<T>((ConditionalSubscriber<? super T>)a, predicate);
            } else {
                parents[i] = new ParallelFilterSubscriber<T>(a, predicate);
            }
        }

        source.subscribe(parents);
    }

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

    abstract static class BaseFilterSubscriber<T> implements ConditionalSubscriber<T>, Subscription {
        final Predicate<? super T> predicate;

        Subscription upstream;

        boolean done;

        BaseFilterSubscriber(Predicate<? super T> predicate) {
            this.predicate = predicate;
        }

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

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

        @Override
        public final void onNext(T t) {
            if (!tryOnNext(t) && !done) {
                upstream.request(1);
            }
        }
    }

    static final class ParallelFilterSubscriber<T> extends BaseFilterSubscriber<T> {

        final Subscriber<? super T> downstream;

        ParallelFilterSubscriber(Subscriber<? super T> actual, Predicate<? super T> predicate) {
            super(predicate);
            this.downstream = actual;
        }

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

                downstream.onSubscribe(this);
            }
        }

        @Override
        public boolean tryOnNext(T t) {
            if (!done) {
                boolean b;

                try {
                    b = predicate.test(t);
                } catch (Throwable ex) {
                    Exceptions.throwIfFatal(ex);
                    cancel();
                    onError(ex);
                    return false;
                }

                if (b) {
                    downstream.onNext(t);
                    return true;
                }
            }
            return false;
        }

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

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

    static final class ParallelFilterConditionalSubscriber<T> extends BaseFilterSubscriber<T> {

        final ConditionalSubscriber<? super T> downstream;

        ParallelFilterConditionalSubscriber(ConditionalSubscriber<? super T> actual, Predicate<? super T> predicate) {
            super(predicate);
            this.downstream = actual;
        }

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

                downstream.onSubscribe(this);
            }
        }

        @Override
        public boolean tryOnNext(T t) {
            if (!done) {
                boolean b;

                try {
                    b = predicate.test(t);
                } catch (Throwable ex) {
                    Exceptions.throwIfFatal(ex);
                    cancel();
                    onError(ex);
                    return false;
                }

                if (b) {
                    return downstream.tryOnNext(t);
                }
            }
            return false;
        }

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

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