content: /*
   * Copyright 2022 The FeatHub Authors
   *
   * 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
   *
   *     https://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.alibaba.feathub.flink.udf.aggregation;
  
  import org.apache.flink.table.api.DataTypes;
  import org.apache.flink.table.types.DataType;
  
  import java.util.List;
  import java.util.stream.Collectors;
  
  /** An aggregate function that collects values into a list. */
  public class CollectListAggFunc extends RawDataAccumulatingAggFunc<Object, Object> {
      private final DataType inDataType;
  
      public CollectListAggFunc(DataType inDataType) {
          this.inDataType = inDataType;
      }
  
      @Override
      public Object getResult(RawDataAccumulator<Object> accumulator) {
          return toArray(
                  accumulator.rawDataList.stream().map(x -> x.f0).collect(Collectors.toList()));
      }
  
      @Override
      public DataType getResultDatatype() {
          return DataTypes.ARRAY(inDataType);
      }
  
      public static Object toArray(List<Object> values) {
          if (values.isEmpty()) {
              return new Object[0];
          }
  
          if (values.get(0) instanceof Long) {
              return values.toArray(new Long[0]);
          } else if (values.get(0) instanceof Integer) {
              return values.toArray(new Integer[0]);
          } else if (values.get(0) instanceof Double) {
              return values.toArray(new Double[0]);
          } else if (values.get(0) instanceof Float) {
              return values.toArray(new Float[0]);
          } else if (values.get(0) instanceof String) {
              return values.toArray(new String[0]);
          }
  
          throw new RuntimeException(
                  String.format(
                          "Unsupported type for COLLECT_LIST %s.",
                          values.get(0).getClass().getName()));
      }
  }
  