/*
 * 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.calcite.sql.fun;

import org.apache.calcite.rel.type.RelDataType;
import org.apache.calcite.rel.type.RelDataTypeFactory;
import org.apache.calcite.sql.SqlAggFunction;
import org.apache.calcite.sql.SqlFunctionCategory;
import org.apache.calcite.sql.SqlKind;
import org.apache.calcite.sql.type.OperandTypes;
import org.apache.calcite.sql.type.ReturnTypes;

import com.google.common.collect.ImmutableList;

import java.util.List;

/**
 * <code>HISTOGRAM</code> is the base operator that supports the Histogram
 * MIN/MAX aggregate functions. It returns the sum of the values which go
 * into it. It has precisely one argument of numeric type (<code>int</code>,
 * <code>long</code>, <code>float</code>, <code>double</code>); results are
 * retrieved using (<code>HistogramMin</code>) and (<code>HistogramMax</code>).
 */
public class SqlHistogramAggFunction extends SqlAggFunction {
  //~ Instance fields --------------------------------------------------------

  @Deprecated // to be removed before 2.0
  private final RelDataType type;

  //~ Constructors -----------------------------------------------------------

  public SqlHistogramAggFunction(RelDataType type) {
    super(
        "$HISTOGRAM",
        null,
        SqlKind.OTHER_FUNCTION,
        ReturnTypes.HISTOGRAM,
        null,
        OperandTypes.NUMERIC_OR_STRING,
        SqlFunctionCategory.NUMERIC,
        false,
        false);
    this.type = type;
  }

  //~ Methods ----------------------------------------------------------------

  @SuppressWarnings("deprecation")
  public List<RelDataType> getParameterTypes(RelDataTypeFactory typeFactory) {
    return ImmutableList.of(type);
  }

  @Deprecated // to be removed before 2.0
  public RelDataType getType() {
    return type;
  }

  @SuppressWarnings("deprecation")
  public RelDataType getReturnType(RelDataTypeFactory typeFactory) {
    return type;
  }
}

// End SqlHistogramAggFunction.java
