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The module for FunctionalJ Core.
There is a newer version: 1.0.17
// ============================================================================
// Copyright (c) 2017-2019 Nawapunth Manusitthipol (NawaMan - http://nawaman.net).
// ----------------------------------------------------------------------------
// MIT License
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
// ============================================================================
package functionalj.promise;

import static java.util.Objects.requireNonNull;

import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;

import functionalj.list.FuncList;
import functionalj.list.ImmutableList;
import functionalj.result.Result;
import lombok.val;
import lombok.experimental.Delegate;

public class RaceResult implements HasPromise {
    
    @SafeVarargs
    public static  RaceResult of(StartableAction ... actions) {
        return Race(FuncList.of(actions));
    }
    
    public static  RaceResult from(List> actions) {
        return Race(FuncList.from(actions));
    }
    
    @SafeVarargs
    public static  RaceResult Race(StartableAction ... actions) {
        return Race(FuncList.of(actions));
    }
    
    public static  RaceResult Race(List> actions) {
        DeferAction deferAction   = DeferAction.createNew();
        val            pendingAction = deferAction.start();
        
        val startedActions = FuncList.from(actions)
                .filterNonNull()
                .map(StartableAction::start)
                .toImmutableList();
        
        val counter = new AtomicInteger(actions.size());
        val hasNull = new AtomicBoolean(false);
        startedActions
        .forEach(action -> {
            action.onComplete(result -> {
                result.ifPresent(value ->{
                    pendingAction.complete(value);
                    startedActions.forEach(PendingAction::abort);
                });
                result.ifNull(() -> hasNull.set(true));
                
                int count = counter.decrementAndGet();
                if (count == 0) {
                    startedActions.forEach(PendingAction::abort);
                    
                    if (hasNull.get())
                         pendingAction.completeWith(Result.ofNull());
                    else pendingAction.abort("Finish without non-null result.");
                }
            });
        });
        
        val promise  = pendingAction.getPromise();
        val promises = startedActions.map(PendingAction::getPromise).toImmutableList();
        val race     = new RaceResult(promise, promises);
        return race;
    }
    
    private final Promise                promise;
    private final ImmutableList> eachPromises;
    
    RaceResult(Promise promise, ImmutableList> eachPromises) {
        this.promise      = requireNonNull(promise);
        this.eachPromises = requireNonNull(eachPromises);
    }
    
    @Delegate
    public Promise getResultPromise() {
        return promise;
    }
    public FuncList> getEachPromises() {
        return eachPromises;
    }
    
}