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/**
 * Copyright 2014 Netflix, Inc.
 *
 * 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 rx.internal.operators;

import java.util.*;
import java.util.concurrent.atomic.*;

import rx.*;
import rx.Observable;
import rx.Observable.Operator;
import rx.exceptions.Exceptions;
import rx.functions.*;
import rx.internal.util.atomic.SpscAtomicArrayQueue;
import rx.internal.util.unsafe.*;
import rx.subscriptions.Subscriptions;

public final class OperatorEagerConcatMap implements Operator {
    final Func1> mapper;
    final int bufferSize;
    private final int maxConcurrent;
    public OperatorEagerConcatMap(Func1> mapper, int bufferSize, int maxConcurrent) {
        this.mapper = mapper;
        this.bufferSize = bufferSize;
        this.maxConcurrent = maxConcurrent;
    }
    
    @Override
    public Subscriber call(Subscriber t) {
        EagerOuterSubscriber outer = new EagerOuterSubscriber(mapper, bufferSize, maxConcurrent, t);
        outer.init();
        return outer;
    }
    
    static final class EagerOuterProducer extends AtomicLong implements Producer {
        /** */
        private static final long serialVersionUID = -657299606803478389L;
        
        final EagerOuterSubscriber parent;
        
        public EagerOuterProducer(EagerOuterSubscriber parent) {
            this.parent = parent;
        }

        @Override
        public void request(long n) {
            if (n < 0) {
                throw new IllegalStateException("n >= 0 required but it was " + n);
            }
            
            if (n > 0) {
                BackpressureUtils.getAndAddRequest(this, n);
                parent.drain();
            }
        }
    }
    
    static final class EagerOuterSubscriber extends Subscriber {
        final Func1> mapper;
        final int bufferSize;
        final Subscriber actual;
        
        final Queue> subscribers;
        
        volatile boolean done;
        Throwable error;
        
        volatile boolean cancelled;
        
        final AtomicInteger wip;
        private EagerOuterProducer sharedProducer;
        
        public EagerOuterSubscriber(Func1> mapper, int bufferSize,
                int maxConcurrent, Subscriber actual) {
            this.mapper = mapper;
            this.bufferSize = bufferSize;
            this.actual = actual;
            this.subscribers = new LinkedList>();
            this.wip = new AtomicInteger();
            request(maxConcurrent == Integer.MAX_VALUE ? Long.MAX_VALUE : maxConcurrent);
        }
        
        void init() {
            sharedProducer = new EagerOuterProducer(this);
            add(Subscriptions.create(new Action0() {
                @Override
                public void call() {
                    cancelled = true;
                    if (wip.getAndIncrement() == 0) {
                        cleanup();
                    }
                }
            }));
            actual.add(this);
            actual.setProducer(sharedProducer);
        }
        
        void cleanup() {
            List list;
            synchronized (subscribers) {
                list = new ArrayList(subscribers);
                subscribers.clear();
            }
            
            for (Subscription s : list) {
                s.unsubscribe();
            }
        }
        
        @Override
        public void onNext(T t) {
            Observable observable;
            
            try {
                observable = mapper.call(t);
            } catch (Throwable e) {
                Exceptions.throwOrReport(e, actual, t);
                return;
            }
            
            if (cancelled) {
                return;
            }
            
            EagerInnerSubscriber inner = new EagerInnerSubscriber(this, bufferSize);
            
            synchronized (subscribers) {
                if (cancelled) {
                    return;
                }
                subscribers.add(inner);
            }
            if (cancelled) {
                return;
            }
            observable.unsafeSubscribe(inner);
            drain();
        }
        
        @Override
        public void onError(Throwable e) {
            error = e;
            done = true;
            drain();
        }
        
        @Override
        public void onCompleted() {
            done = true;
            drain();
        }
        
        void drain() {
            if (wip.getAndIncrement() != 0) {
                return;
            }
            int missed = 1;
            
            final AtomicLong requested = sharedProducer;
            final Subscriber actualSubscriber = this.actual;
            final NotificationLite nl = NotificationLite.instance();
            
            for (;;) {
                
                if (cancelled) {
                    cleanup();
                    return;
                }
                
                EagerInnerSubscriber innerSubscriber;
                
                boolean outerDone = done;
                synchronized (subscribers) {
                    innerSubscriber = subscribers.peek();
                }
                boolean empty = innerSubscriber == null;
                
                if (outerDone) {
                    Throwable error = this.error;
                    if (error != null) {
                        cleanup();
                        actualSubscriber.onError(error);
                        return;
                    } else
                    if (empty) {
                        actualSubscriber.onCompleted();
                        return;
                    }
                }

                if (!empty) {
                    long requestedAmount = requested.get();
                    long emittedAmount = 0L;
                    
                    Queue