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.maybe;

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;

Subscribes to the MaybeSource returned by a function if the main source signals an onError.
Type parameters:
<T> – the value type/**
 * Subscribes to the MaybeSource returned by a function if the main source signals an onError.
 * 
 * @param <T> the value type
 */
public final class MaybeOnErrorNext<T> extends AbstractMaybeWithUpstream<T, T> {

    final Function<? super Throwable, ? extends MaybeSource<? extends T>> resumeFunction;

    final boolean allowFatal;

    public MaybeOnErrorNext(MaybeSource<T> source,
            Function<? super Throwable, ? extends MaybeSource<? extends T>> resumeFunction,
                    boolean allowFatal) {
        super(source);
        this.resumeFunction = resumeFunction;
        this.allowFatal = allowFatal;
    }

    @Override
    protected void subscribeActual(MaybeObserver<? super T> observer) {
        source.subscribe(new OnErrorNextMaybeObserver<T>(observer, resumeFunction, allowFatal));
    }

    static final class OnErrorNextMaybeObserver<T>
    extends AtomicReference<Disposable>
    implements MaybeObserver<T>, Disposable {

        private static final long serialVersionUID = 2026620218879969836L;

        final MaybeObserver<? super T> downstream;

        final Function<? super Throwable, ? extends MaybeSource<? extends T>> resumeFunction;

        final boolean allowFatal;

        OnErrorNextMaybeObserver(MaybeObserver<? super T> actual,
                Function<? super Throwable, ? extends MaybeSource<? extends T>> resumeFunction,
                        boolean allowFatal) {
            this.downstream = actual;
            this.resumeFunction = resumeFunction;
            this.allowFatal = allowFatal;
        }

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

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

        @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) {
            if (!allowFatal && !(e instanceof Exception)) {
                downstream.onError(e);
                return;
            }
            MaybeSource<? extends T> m;

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

            DisposableHelper.replace(this, null);

            m.subscribe(new NextMaybeObserver<T>(downstream, this));
        }

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

        static final class NextMaybeObserver<T> implements MaybeObserver<T> {
            final MaybeObserver<? super T> downstream;

            final AtomicReference<Disposable> upstream;

            NextMaybeObserver(MaybeObserver<? super T> actual, AtomicReference<Disposable> d) {
                this.downstream = actual;
                this.upstream = d;
            }

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

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

            @Override
            public void onError(Throwable e) {
                downstream.onError(e);
            }

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