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/*
 * 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.hazelcast.org.apache.calcite.sql.fun;

import com.hazelcast.org.apache.calcite.avatica.util.TimeUnit;
import com.hazelcast.org.apache.calcite.rel.type.RelDataTypeFactory;
import com.hazelcast.org.apache.calcite.sql.SqlFunction;
import com.hazelcast.org.apache.calcite.sql.SqlFunctionCategory;
import com.hazelcast.org.apache.calcite.sql.SqlKind;
import com.hazelcast.org.apache.calcite.sql.type.OperandTypes;
import com.hazelcast.org.apache.calcite.sql.type.SqlReturnTypeInference;
import com.hazelcast.org.apache.calcite.sql.type.SqlTypeFamily;
import com.hazelcast.org.apache.calcite.sql.type.SqlTypeName;

/**
 * The TIMESTAMPDIFF function, which calculates the difference
 * between two timestamps.
 *
 * The SQL syntax is
 *
 * 

 * TIMESTAMPDIFF(timestamp interval, timestamp,
 * timestamp)
 * 
 *
 * The interval time unit can one of the following literals:

 * NANOSECOND (and synonym SQL_TSI_FRAC_SECOND)
 * 
MICROSECOND (and synonyms SQL_TSI_MICROSECOND, FRAC_SECOND)
 * 
SECOND (and synonym SQL_TSI_SECOND)
 * 
MINUTE (and synonym  SQL_TSI_MINUTE)
 * 
HOUR (and synonym  SQL_TSI_HOUR)
 * 
DAY (and synonym SQL_TSI_DAY)
 * 
WEEK (and synonym  SQL_TSI_WEEK)
 * 
MONTH (and synonym SQL_TSI_MONTH)
 * 
QUARTER (and synonym SQL_TSI_QUARTER)
 * 
YEAR (and synonym  SQL_TSI_YEAR)
 * 
 *
 * Returns difference between two timestamps in indicated timestamp
 * interval.
 */
class SqlTimestampDiffFunction extends SqlFunction {
  /** Creates a SqlTimestampDiffFunction. */
  private static final SqlReturnTypeInference RETURN_TYPE_INFERENCE =
      opBinding -> {
        final RelDataTypeFactory typeFactory = opBinding.getTypeFactory();
        SqlTypeName sqlTypeName =
            opBinding.getOperandLiteralValue(0, TimeUnit.class) == TimeUnit.NANOSECOND
                ? SqlTypeName.BIGINT
                : SqlTypeName.INTEGER;
        return typeFactory.createTypeWithNullability(
            typeFactory.createSqlType(sqlTypeName),
            opBinding.getOperandType(1).isNullable()
            || opBinding.getOperandType(2).isNullable());
      };

  SqlTimestampDiffFunction() {
    super("TIMESTAMPDIFF", SqlKind.TIMESTAMP_DIFF,
        RETURN_TYPE_INFERENCE, null,
        OperandTypes.family(SqlTypeFamily.ANY, SqlTypeFamily.DATETIME,
            SqlTypeFamily.DATETIME),
        SqlFunctionCategory.TIMEDATE);
  }
}