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 io.reactivex.*;
import io.reactivex.disposables.Disposable;
import io.reactivex.exceptions.*;
import io.reactivex.functions.BiConsumer;
import io.reactivex.internal.disposables.DisposableHelper;

Calls a BiConsumer with the success, error values of the upstream Maybe or with two nulls if
the Maybe completed.
Type parameters:
<T> – the value type/**
 * Calls a BiConsumer with the success, error values of the upstream Maybe or with two nulls if
 * the Maybe completed.
 *
 * @param <T> the value type
 */
public final class MaybeDoOnEvent<T> extends AbstractMaybeWithUpstream<T, T> {

    final BiConsumer<? super T, ? super Throwable> onEvent;

    public MaybeDoOnEvent(MaybeSource<T> source, BiConsumer<? super T, ? super Throwable> onEvent) {
        super(source);
        this.onEvent = onEvent;
    }

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

    static final class DoOnEventMaybeObserver<T> implements MaybeObserver<T>, Disposable {
        final MaybeObserver<? super T> downstream;

        final BiConsumer<? super T, ? super Throwable> onEvent;

        Disposable upstream;

        DoOnEventMaybeObserver(MaybeObserver<? super T> actual, BiConsumer<? super T, ? super Throwable> onEvent) {
            this.downstream = actual;
            this.onEvent = onEvent;
        }

        @Override
        public void dispose() {
            upstream.dispose();
            upstream = DisposableHelper.DISPOSED;
        }

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

        @Override
        public void onSubscribe(Disposable d) {
            if (DisposableHelper.validate(this.upstream, d)) {
                this.upstream = d;

                downstream.onSubscribe(this);
            }
        }

        @Override
        public void onSuccess(T value) {
            upstream = DisposableHelper.DISPOSED;

            try {
                onEvent.accept(value, null);
            } catch (Throwable ex) {
                Exceptions.throwIfFatal(ex);
                downstream.onError(ex);
                return;
            }

            downstream.onSuccess(value);
        }

        @Override
        public void onError(Throwable e) {
            upstream = DisposableHelper.DISPOSED;

            try {
                onEvent.accept(null, e);
            } catch (Throwable ex) {
                Exceptions.throwIfFatal(ex);
                e = new CompositeException(e, ex);
            }

            downstream.onError(e);
        }

        @Override
        public void onComplete() {
            upstream = DisposableHelper.DISPOSED;

            try {
                onEvent.accept(null, null);
            } catch (Throwable ex) {
                Exceptions.throwIfFatal(ex);
                downstream.onError(ex);
                return;
            }

            downstream.onComplete();
        }
    }
}