/**
 * 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.hadoop.hive.ql.optimizer.calcite.reloperators;

import java.util.Set;

import org.apache.calcite.sql.SqlFunction;
import org.apache.calcite.sql.SqlFunctionCategory;
import org.apache.calcite.sql.SqlKind;
import org.apache.calcite.sql.SqlOperatorBinding;
import org.apache.calcite.sql.fun.SqlMonotonicUnaryFunction;
import org.apache.calcite.sql.type.OperandTypes;
import org.apache.calcite.sql.type.ReturnTypes;
import org.apache.calcite.sql.validate.SqlMonotonicity;

import com.google.common.collect.Sets;

public class HiveFloorDate extends SqlMonotonicUnaryFunction {

  public static final SqlFunction YEAR = new HiveFloorDate("FLOOR_YEAR");
  public static final SqlFunction QUARTER = new HiveFloorDate("FLOOR_QUARTER");
  public static final SqlFunction MONTH = new HiveFloorDate("FLOOR_MONTH");
  public static final SqlFunction WEEK = new HiveFloorDate("FLOOR_WEEK");
  public static final SqlFunction DAY = new HiveFloorDate("FLOOR_DAY");
  public static final SqlFunction HOUR = new HiveFloorDate("FLOOR_HOUR");
  public static final SqlFunction MINUTE = new HiveFloorDate("FLOOR_MINUTE");
  public static final SqlFunction SECOND = new HiveFloorDate("FLOOR_SECOND");

  public static final Set<SqlFunction> ALL_FUNCTIONS =
          Sets.newHashSet(YEAR, QUARTER, MONTH, WEEK, DAY, HOUR, MINUTE, SECOND);

  private HiveFloorDate(String name) {
    super(name, SqlKind.FLOOR, ReturnTypes.ARG0_OR_EXACT_NO_SCALE, null,
        OperandTypes.sequence(
            "'" + SqlKind.FLOOR + "(<DATE> TO <TIME_UNIT>)'\n"
            + "'" + SqlKind.FLOOR + "(<TIME> TO <TIME_UNIT>)'\n"
            + "'" + SqlKind.FLOOR + "(<TIMESTAMP> TO <TIME_UNIT>)'",
            OperandTypes.DATETIME,
            OperandTypes.ANY),
        SqlFunctionCategory.NUMERIC);
  }

  @Override
  public SqlMonotonicity getMonotonicity(SqlOperatorBinding call) {
    // Monotonic iff its first argument is, but not strict.
    return call.getOperandMonotonicity(0).unstrict();
  }

}
