/*
 * Copyright (c) 2008-2017, Hazelcast, Inc. All Rights Reserved.
 *
 * 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 com.hazelcast.aggregation.impl;

import com.hazelcast.aggregation.Aggregator;
import com.hazelcast.nio.ObjectDataInput;
import com.hazelcast.nio.ObjectDataOutput;
import com.hazelcast.nio.serialization.IdentifiedDataSerializable;

import java.io.IOException;
import java.util.HashSet;
import java.util.Set;

public final class DistinctValuesAggregator<I, R> extends AbstractAggregator<I, R, Set<R>> implements IdentifiedDataSerializable {
    Set<R> values = new HashSet<R>();

    public DistinctValuesAggregator() {
        super();
    }

    public DistinctValuesAggregator(String attributePath) {
        super(attributePath);
    }

    @Override
    public void accumulateExtracted(R value) {
        values.add(value);
    }

    @Override
    public void combine(Aggregator aggregator) {
        DistinctValuesAggregator distinctValuesAggregator = (DistinctValuesAggregator) aggregator;
        this.values.addAll(distinctValuesAggregator.values);
    }

    @Override
    public Set<R> aggregate() {
        return values;
    }

    @Override
    public int getFactoryId() {
        return AggregatorDataSerializerHook.F_ID;
    }

    @Override
    public int getId() {
        return AggregatorDataSerializerHook.DISTINCT_VALUES;
    }

    @Override
    public void writeData(ObjectDataOutput out) throws IOException {
        out.writeUTF(attributePath);
        out.writeInt(values.size());
        for (Object value : values) {
            out.writeObject(value);
        }
    }

    @Override
    public void readData(ObjectDataInput in) throws IOException {
        this.attributePath = in.readUTF();
        int count = in.readInt();
        this.values = new HashSet<R>(count);
        for (int i = 0; i < count; i++) {
            values.add((R) in.readObject());
        }
    }

}