/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.kylin.measure.map.bitmap;

/**
 * Bitmap-map-based distinct count UDAF, called by calcite runtime.
 */
public class BitmapMapDistinctCountAggFunc {

    public static BitmapMapAggregator init() {
        return new BitmapMapAggregator();
    }

    public static BitmapMapAggregator add(BitmapMapAggregator agg, Object value) {
        agg.aggregate((BitmapCounterMap) value);
        return agg;
    }

    public static BitmapMapAggregator merge(BitmapMapAggregator agg, Object value) {
        BitmapMapAggregator agg2 = (BitmapMapAggregator) value;
        if (agg2.getState() == null) {
            return agg;
        }
        return add(agg, agg2.getState());
    }

    public static long result(BitmapMapAggregator agg) {
        BitmapCounterMap finalState = agg.getState();
        return finalState == null ? 0 : finalState.getCount();
    }
}
