/*
 * 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.skywalking.oap.server.core.analysis.metrics;

import lombok.Getter;
import lombok.Setter;
import org.apache.skywalking.oap.server.core.analysis.metrics.annotation.ConstOne;
import org.apache.skywalking.oap.server.core.analysis.metrics.annotation.Entrance;
import org.apache.skywalking.oap.server.core.analysis.metrics.annotation.MetricsFunction;
import org.apache.skywalking.oap.server.core.analysis.metrics.annotation.SourceFrom;
import org.apache.skywalking.oap.server.core.query.sql.Function;
import org.apache.skywalking.oap.server.core.storage.annotation.Column;

@MetricsFunction(functionName = "doubleAvg")
public abstract class DoubleAvgMetrics extends Metrics implements DoubleValueHolder {

    protected static final String SUMMATION = "summation";
    protected static final String COUNT = "count";
    protected static final String VALUE = "value";

    @Getter
    @Setter
    @Column(columnName = SUMMATION, storageOnly = true)
    private double summation;
    @Getter
    @Setter
    @Column(columnName = COUNT, storageOnly = true)
    private long count;
    @Getter
    @Setter
    @Column(columnName = VALUE, dataType = Column.ValueDataType.COMMON_VALUE, function = Function.Avg)
    private double value;

    @Entrance
    public final void combine(@SourceFrom double summation, @ConstOne long count) {
        this.summation += summation;
        this.count += count;
    }

    @Override
    public final void combine(Metrics metrics) {
        DoubleAvgMetrics doubleAvgMetrics = (DoubleAvgMetrics) metrics;
        combine(doubleAvgMetrics.summation, doubleAvgMetrics.count);
    }

    @Override
    public final void calculate() {
        this.value = this.summation / this.count;
    }
}
