/**
 * 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.concurrent.atomic.AtomicIntegerFieldUpdater;
import rx.Observable;
import rx.Scheduler;
import rx.Subscriber;
import rx.functions.Action0;
import rx.functions.Func2;
import rx.schedulers.Schedulers;
import rx.subscriptions.SerialSubscription;

public final class OperatorRetryWithPredicate<T> implements Observable.Operator<T, Observable<T>> {
    final Func2<Integer, Throwable, Boolean> predicate;
    public OperatorRetryWithPredicate(Func2<Integer, Throwable, Boolean> predicate) {
        this.predicate = predicate;
    }

    @Override
    public Subscriber<? super Observable<T>> call(final Subscriber<? super T> child) {
        final Scheduler.Worker inner = Schedulers.trampoline().createWorker();
        child.add(inner);
        
        final SerialSubscription serialSubscription = new SerialSubscription();
        // add serialSubscription so it gets unsubscribed if child is unsubscribed
        child.add(serialSubscription);
        
        return new SourceSubscriber<T>(child, predicate, inner, serialSubscription);
    }
    
    static final class SourceSubscriber<T> extends Subscriber<Observable<T>> {
        final Subscriber<? super T> child;
        final Func2<Integer, Throwable, Boolean> predicate;
        final Scheduler.Worker inner;
        final SerialSubscription serialSubscription;
        
        volatile int attempts;
        @SuppressWarnings("rawtypes")
        static final AtomicIntegerFieldUpdater<SourceSubscriber> ATTEMPTS_UPDATER
                = AtomicIntegerFieldUpdater.newUpdater(SourceSubscriber.class, "attempts");

        public SourceSubscriber(Subscriber<? super T> child, final Func2<Integer, Throwable, Boolean> predicate, Scheduler.Worker inner, 
                SerialSubscription serialSubscription) {
            this.child = child;
            this.predicate = predicate;
            this.inner = inner;
            this.serialSubscription = serialSubscription;
        }
        
        
        @Override
            public void onCompleted() {
                // ignore as we expect a single nested Observable<T>
            }

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

            @Override
            public void onNext(final Observable<T> o) {
                inner.schedule(new Action0() {

                    @Override
                    public void call() {
                        final Action0 _self = this;
                        ATTEMPTS_UPDATER.incrementAndGet(SourceSubscriber.this);

                        // new subscription each time so if it unsubscribes itself it does not prevent retries
                        // by unsubscribing the child subscription
                        Subscriber<T> subscriber = new Subscriber<T>() {

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

                            @Override
                            public void onError(Throwable e) {
                                if (predicate.call(attempts, e) && !inner.isUnsubscribed()) {
                                    // retry again
                                    inner.schedule(_self);
                                } else {
                                    // give up and pass the failure
                                    child.onError(e);
                                }
                            }

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

                        };
                        // register this Subscription (and unsubscribe previous if exists) 
                        serialSubscription.set(subscriber);
                        o.unsafeSubscribe(subscriber);
                    }
                });
            }
    }
}