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.completable;

import java.util.concurrent.atomic.AtomicInteger;

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

public final class CompletableConcatArray extends Completable {
    final CompletableSource[] sources;

    public CompletableConcatArray(CompletableSource[] sources) {
        this.sources = sources;
    }

    @Override
    public void subscribeActual(CompletableObserver observer) {
        ConcatInnerObserver inner = new ConcatInnerObserver(observer, sources);
        observer.onSubscribe(inner.sd);
        inner.next();
    }

    static final class ConcatInnerObserver extends AtomicInteger implements CompletableObserver {

        private static final long serialVersionUID = -7965400327305809232L;

        final CompletableObserver downstream;
        final CompletableSource[] sources;

        int index;

        final SequentialDisposable sd;

        ConcatInnerObserver(CompletableObserver actual, CompletableSource[] sources) {
            this.downstream = actual;
            this.sources = sources;
            this.sd = new SequentialDisposable();
        }

        @Override
        public void onSubscribe(Disposable d) {
            sd.replace(d);
        }

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

        @Override
        public void onComplete() {
            next();
        }

        void next() {
            if (sd.isDisposed()) {
                return;
            }

            if (getAndIncrement() != 0) {
                return;
            }

            CompletableSource[] a = sources;
            do {
                if (sd.isDisposed()) {
                    return;
                }

                int idx = index++;
                if (idx == a.length) {
                    downstream.onComplete();
                    return;
                }

                a[idx].subscribe(this);
            } while (decrementAndGet() != 0);
        }
    }
}