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package org.aksw.jenax.arq.aggregation;

import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.function.BiFunction;

import org.aksw.commons.collector.domain.Accumulator;

/**
 * An ggregator that initialized with a static map
 *
 * Every key in the map is passed to a function that yields the value to be passed as the new binding to the child accumulator.
 * Hence, this accumulator is 'map'-centric as its the map's keys that drive the lookup
 *
 * TODO Clarify relation between AggObject, AggMap and AggStaticMultiplex
 *
 * @author raven
 *
 * @param 
 * @param 
 */
public class AccStaticMultiplex
    implements Accumulator> {
    //protected Function> bindingToKeys;

    /**
     * Obtain the childBinding based on the current binding and the current key of the map
     */
    protected BiFunction childBinding;
    protected Map> keyToSubAcc;

    public AccStaticMultiplex(BiFunction childBinding, Map> keyToSubAcc) {
        this.childBinding = childBinding;
        this.keyToSubAcc = keyToSubAcc;
    }

    @Override
    public void accumulate(B binding, E env) {
        for(Entry> e : keyToSubAcc.entrySet()) {
            K k = e.getKey();
            Accumulator subAcc = e.getValue();

            U u = childBinding.apply(binding, k);

            subAcc.accumulate(u);
        }
    }

    @Override
    public Map getValue() {
        Map result = new HashMap<>(keyToSubAcc.size());
        for(Entry> e : keyToSubAcc.entrySet()) {
            K k = e.getKey();
            Accumulator subAcc = e.getValue();
            V v = subAcc.getValue();

            result.put(k, v);
        }

        return result;
    }

    public static  Accumulator> create(BiFunction childBinding, Map> keyToSubAcc) {
        AccStaticMultiplex result = new AccStaticMultiplex<>(childBinding, keyToSubAcc);
        return result;
    }
}