content: /*
   * 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 com.ververica.field.dynamicrules.accumulators;
  
  import java.math.BigDecimal;
  import org.apache.flink.annotation.Public;
  import org.apache.flink.api.common.accumulators.Accumulator;
  import org.apache.flink.api.common.accumulators.SimpleAccumulator;
  
  /**
   * An accumulator that computes the average value. Input can be {@code long}, {@code integer}, or
   * {@code double} and the result is {@code double}.
   */
  @Public
  public class AverageAccumulator implements SimpleAccumulator<BigDecimal> {
  
    private static final long serialVersionUID = 1L;
  
    private long count;
  
    private BigDecimal sum;
  
    @Override
    public void add(BigDecimal value) {
      this.count++;
      this.sum = sum.add(value);
    }
  
    @Override
    public BigDecimal getLocalValue() {
      if (this.count == 0) {
        return BigDecimal.ZERO;
      }
      return this.sum.divide(new BigDecimal(count));
    }
  
    @Override
    public void resetLocal() {
      this.count = 0;
      this.sum = BigDecimal.ZERO;
    }
  
    @Override
    public void merge(Accumulator<BigDecimal, BigDecimal> other) {
      if (other instanceof AverageAccumulator) {
        AverageAccumulator avg = (AverageAccumulator) other;
        this.count += avg.count;
        this.sum = sum.add(avg.sum);
      } else {
        throw new IllegalArgumentException("The merged accumulator must be AverageAccumulator.");
      }
    }
  
    @Override
    public AverageAccumulator clone() {
      AverageAccumulator average = new AverageAccumulator();
      average.count = this.count;
      average.sum = this.sum;
      return average;
    }
  
    @Override
    public String toString() {
      return "AverageAccumulator " + this.getLocalValue() + " for " + this.count + " elements";
    }
  }
  