content: /*
   * Copyright © 2018-2025 Commonwealth Scientific and Industrial Research
   * Organisation (CSIRO) ABN 41 687 119 230.
   *
   * 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 au.csiro.pathling.sql.misc;
  
  import au.csiro.pathling.sql.udf.SqlFunction2;
  import jakarta.annotation.Nullable;
  import java.io.Serial;
  import java.math.BigDecimal;
  import java.math.RoundingMode;
  import java.util.Optional;
  import org.apache.spark.sql.types.DataType;
  import org.apache.spark.sql.types.DataTypes;
  
  /**
   * Spark UDF to convert a Decimal type to a valid Decimal literal string with the optionally
   * provided scale.
   * <p>
   * If the scale is less than the number of decimal places in the Decimal struct, the function floors
   * the decimal value.
   * <p>
   * If the scale is negative, the function returns null.
   *
   * @author Piotr Szul
   */
  public class DecimalToLiteral implements SqlFunction2<BigDecimal, Integer, String> {
  
    /**
     * The name of this function when used within SQL.
     */
    public static final String FUNCTION_NAME = "decimal_to_literal";
  
    @Serial
    private static final long serialVersionUID = 1L;
  
    @Override
    public String getName() {
      return FUNCTION_NAME;
    }
  
    @Override
    public DataType getReturnType() {
      return DataTypes.StringType;
    }
  
    @Override
    @Nullable
    public String call(@Nullable final BigDecimal value, @Nullable final Integer scale) {
      if (value == null || (scale != null && scale < 0)) {
        return null;
      }
      return Optional.ofNullable(scale)
          .map(s -> value.setScale(s, RoundingMode.FLOOR))
          .orElse(value.stripTrailingZeros())
          .toString();
    }
  }
  