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.observable;

import io.reactivex.*;
import io.reactivex.disposables.Disposable;
import io.reactivex.internal.disposables.SequentialDisposable;
import io.reactivex.plugins.RxJavaPlugins;

Delays the subscription to the main source until the other
observable fires an event or completes.
Type parameters:
<T> – the main type
<U> – the other value type, ignored/**
 * Delays the subscription to the main source until the other
 * observable fires an event or completes.
 * @param <T> the main type
 * @param <U> the other value type, ignored
 */
public final class ObservableDelaySubscriptionOther<T, U> extends Observable<T> {
    final ObservableSource<? extends T> main;
    final ObservableSource<U> other;

    public ObservableDelaySubscriptionOther(ObservableSource<? extends T> main, ObservableSource<U> other) {
        this.main = main;
        this.other = other;
    }

    @Override
    public void subscribeActual(final Observer<? super T> child) {
        final SequentialDisposable serial = new SequentialDisposable();
        child.onSubscribe(serial);

        Observer<U> otherObserver = new DelayObserver(serial, child);

        other.subscribe(otherObserver);
    }

    final class DelayObserver implements Observer<U> {
        final SequentialDisposable serial;
        final Observer<? super T> child;
        boolean done;

        DelayObserver(SequentialDisposable serial, Observer<? super T> child) {
            this.serial = serial;
            this.child = child;
        }

        @Override
        public void onSubscribe(Disposable d) {
            serial.update(d);
        }

        @Override
        public void onNext(U t) {
            onComplete();
        }

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

        @Override
        public void onComplete() {
            if (done) {
                return;
            }
            done = true;

            main.subscribe(new OnComplete());
        }

        final class OnComplete implements Observer<T> {
            @Override
            public void onSubscribe(Disposable d) {
                serial.update(d);
            }

            @Override
            public void onNext(T value) {
                child.onNext(value);
            }

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

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