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 org.reactivestreams.Subscriber;

import io.reactivex.Flowable;
import io.reactivex.exceptions.*;
import io.reactivex.functions.Function;
import io.reactivex.internal.functions.ObjectHelper;
import io.reactivex.internal.subscribers.SinglePostCompleteSubscriber;

public final class FlowableOnErrorReturn<T> extends AbstractFlowableWithUpstream<T, T> {
    final Function<? super Throwable, ? extends T> valueSupplier;
    public FlowableOnErrorReturn(Flowable<T> source, Function<? super Throwable, ? extends T> valueSupplier) {
        super(source);
        this.valueSupplier = valueSupplier;
    }

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

    static final class OnErrorReturnSubscriber<T>
    extends SinglePostCompleteSubscriber<T, T> {

        private static final long serialVersionUID = -3740826063558713822L;
        final Function<? super Throwable, ? extends T> valueSupplier;

        OnErrorReturnSubscriber(Subscriber<? super T> actual, Function<? super Throwable, ? extends T> valueSupplier) {
            super(actual);
            this.valueSupplier = valueSupplier;
        }

        @Override
        public void onNext(T t) {
            produced++;
            downstream.onNext(t);
        }

        @Override
        public void onError(Throwable t) {
            T v;
            try {
                v = ObjectHelper.requireNonNull(valueSupplier.apply(t), "The valueSupplier returned a null value");
            } catch (Throwable ex) {
                Exceptions.throwIfFatal(ex);
                downstream.onError(new CompositeException(t, ex));
                return;
            }
            complete(v);
        }

        @Override
        public void onComplete() {
            downstream.onComplete();
        }
    }
}