/**
 * 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.joins;

import java.util.Map;
import java.util.concurrent.atomic.AtomicReference;

import rx.Observer;
import rx.functions.Action0;
import rx.functions.Action1;
import rx.functions.Action2;
import rx.functions.Actions;
import rx.functions.Func2;

/**
 * Represents an execution plan for join patterns.
 */
public class Plan2<T1, T2, R> extends Plan0<R> {
    protected Pattern2<T1, T2> expression;
    protected Func2<T1, T2, R> selector;

    public Plan2(Pattern2<T1, T2> expression, Func2<T1, T2, R> selector) {
        this.expression = expression;
        this.selector = selector;
    }

    @Override
    public ActivePlan0 activate(Map<Object, JoinObserver> externalSubscriptions,
            final Observer<R> observer, final Action1<ActivePlan0> deactivate) {
        Action1<Throwable> onError = Actions.onErrorFrom(observer);

        final JoinObserver1<T1> firstJoinObserver = createObserver(externalSubscriptions, expression.first(), onError);
        final JoinObserver1<T2> secondJoinObserver = createObserver(externalSubscriptions, expression.second(), onError);

        final AtomicReference<ActivePlan2<T1, T2>> self = new AtomicReference<ActivePlan2<T1, T2>>();

        ActivePlan2<T1, T2> activePlan = new ActivePlan2<T1, T2>(firstJoinObserver, secondJoinObserver, new Action2<T1, T2>() {
            @Override
            public void call(T1 t1, T2 t2) {
                R result;
                try {
                    result = selector.call(t1, t2);
                } catch (Throwable t) {
                    observer.onError(t);
                    return;
                }
                observer.onNext(result);
            }
        },
                new Action0() {
                    @Override
                    public void call() {
                        firstJoinObserver.removeActivePlan(self.get());
                        secondJoinObserver.removeActivePlan(self.get());
                        deactivate.call(self.get());
                    }
                });

        self.set(activePlan);

        firstJoinObserver.addActivePlan(activePlan);
        secondJoinObserver.addActivePlan(activePlan);

        return activePlan;
    }

}
