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.single;

import java.util.concurrent.atomic.AtomicReference;

import io.reactivex.*;
import io.reactivex.disposables.Disposable;
import io.reactivex.exceptions.*;
import io.reactivex.functions.Function;
import io.reactivex.internal.disposables.DisposableHelper;
import io.reactivex.internal.functions.ObjectHelper;
import io.reactivex.internal.observers.ResumeSingleObserver;

public final class SingleResumeNext<T> extends Single<T> {
    final SingleSource<? extends T> source;

    final Function<? super Throwable, ? extends SingleSource<? extends T>> nextFunction;

    public SingleResumeNext(SingleSource<? extends T> source,
            Function<? super Throwable, ? extends SingleSource<? extends T>> nextFunction) {
        this.source = source;
        this.nextFunction = nextFunction;
    }

    @Override
    protected void subscribeActual(final SingleObserver<? super T> observer) {
        source.subscribe(new ResumeMainSingleObserver<T>(observer, nextFunction));
    }

    static final class ResumeMainSingleObserver<T> extends AtomicReference<Disposable>
    implements SingleObserver<T>, Disposable {
        private static final long serialVersionUID = -5314538511045349925L;

        final SingleObserver<? super T> downstream;

        final Function<? super Throwable, ? extends SingleSource<? extends T>> nextFunction;

        ResumeMainSingleObserver(SingleObserver<? super T> actual,
                Function<? super Throwable, ? extends SingleSource<? extends T>> nextFunction) {
            this.downstream = actual;
            this.nextFunction = nextFunction;
        }

        @Override
        public void onSubscribe(Disposable d) {
            if (DisposableHelper.setOnce(this, d)) {
                downstream.onSubscribe(this);
            }
        }

        @Override
        public void onSuccess(T value) {
            downstream.onSuccess(value);
        }

        @Override
        public void onError(Throwable e) {
            SingleSource<? extends T> source;

            try {
                source = ObjectHelper.requireNonNull(nextFunction.apply(e), "The nextFunction returned a null SingleSource.");
            } catch (Throwable ex) {
                Exceptions.throwIfFatal(ex);
                downstream.onError(new CompositeException(e, ex));
                return;
            }

            source.subscribe(new ResumeSingleObserver<T>(this, downstream));
        }

        @Override
        public void dispose() {
            DisposableHelper.dispose(this);
        }

        @Override
        public boolean isDisposed() {
            return DisposableHelper.isDisposed(get());
        }
    }
}