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.*;

import org.reactivestreams.*;

import io.reactivex.*;
import io.reactivex.disposables.*;
import io.reactivex.internal.disposables.DisposableHelper;
import io.reactivex.internal.subscriptions.SubscriptionHelper;
import io.reactivex.internal.util.*;
import io.reactivex.plugins.RxJavaPlugins;

public final class CompletableMerge extends Completable {
    final Publisher<? extends CompletableSource> source;
    final int maxConcurrency;
    final boolean delayErrors;

    public CompletableMerge(Publisher<? extends CompletableSource> source, int maxConcurrency, boolean delayErrors) {
        this.source = source;
        this.maxConcurrency = maxConcurrency;
        this.delayErrors = delayErrors;
    }

    @Override
    public void subscribeActual(CompletableObserver observer) {
        CompletableMergeSubscriber parent = new CompletableMergeSubscriber(observer, maxConcurrency, delayErrors);
        source.subscribe(parent);
    }

    static final class CompletableMergeSubscriber
    extends AtomicInteger
    implements FlowableSubscriber<CompletableSource>, Disposable {

        private static final long serialVersionUID = -2108443387387077490L;

        final CompletableObserver downstream;
        final int maxConcurrency;
        final boolean delayErrors;

        final AtomicThrowable error;

        final CompositeDisposable set;

        Subscription upstream;

        CompletableMergeSubscriber(CompletableObserver actual, int maxConcurrency, boolean delayErrors) {
            this.downstream = actual;
            this.maxConcurrency = maxConcurrency;
            this.delayErrors = delayErrors;
            this.set = new CompositeDisposable();
            this.error = new AtomicThrowable();
            lazySet(1);
        }

        @Override
        public void dispose() {
            upstream.cancel();
            set.dispose();
        }

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

        @Override
        public void onSubscribe(Subscription s) {
            if (SubscriptionHelper.validate(this.upstream, s)) {
                this.upstream = s;
                downstream.onSubscribe(this);
                if (maxConcurrency == Integer.MAX_VALUE) {
                    s.request(Long.MAX_VALUE);
                } else {
                    s.request(maxConcurrency);
                }
            }
        }

        @Override
        public void onNext(CompletableSource t) {
            getAndIncrement();

            MergeInnerObserver inner = new MergeInnerObserver();
            set.add(inner);
            t.subscribe(inner);
        }

        @Override
        public void onError(Throwable t) {
            if (!delayErrors) {
                set.dispose();

                if (error.addThrowable(t)) {
                    if (getAndSet(0) > 0) {
                        downstream.onError(error.terminate());
                    }
                } else {
                    RxJavaPlugins.onError(t);
                }
            } else {
                if (error.addThrowable(t)) {
                    if (decrementAndGet() == 0) {
                        downstream.onError(error.terminate());
                    }
                } else {
                    RxJavaPlugins.onError(t);
                }
            }
        }

        @Override
        public void onComplete() {
            if (decrementAndGet() == 0) {
                Throwable ex = error.get();
                if (ex != null) {
                    downstream.onError(error.terminate());
                } else {
                    downstream.onComplete();
                }
            }
        }

        void innerError(MergeInnerObserver inner, Throwable t) {
            set.delete(inner);
            if (!delayErrors) {
                upstream.cancel();
                set.dispose();

                if (error.addThrowable(t)) {
                    if (getAndSet(0) > 0) {
                        downstream.onError(error.terminate());
                    }
                } else {
                    RxJavaPlugins.onError(t);
                }
            } else {
                if (error.addThrowable(t)) {
                    if (decrementAndGet() == 0) {
                        downstream.onError(error.terminate());
                    } else {
                        if (maxConcurrency != Integer.MAX_VALUE) {
                            upstream.request(1);
                        }
                    }
                } else {
                    RxJavaPlugins.onError(t);
                }
            }
        }

        void innerComplete(MergeInnerObserver inner) {
            set.delete(inner);
            if (decrementAndGet() == 0) {
                Throwable ex = error.get();
                if (ex != null) {
                    downstream.onError(ex);
                } else {
                    downstream.onComplete();
                }
            } else {
                if (maxConcurrency != Integer.MAX_VALUE) {
                    upstream.request(1);
                }
            }
        }

        final class MergeInnerObserver
        extends AtomicReference<Disposable>
        implements CompletableObserver, Disposable {
            private static final long serialVersionUID = 251330541679988317L;

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

            @Override
            public void onError(Throwable e) {
                innerError(this, e);
            }

            @Override
            public void onComplete() {
                innerComplete(this);
            }

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

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