package brickhouse.udf.date;
/**
 * Copyright 2012 Klout, Inc
 *
 * 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.
 *
 **/

import org.apache.hadoop.hive.ql.exec.UDF;
import org.apache.log4j.Logger;
import org.joda.time.DateTime;
import org.joda.time.format.DateTimeFormatter;

/**
 * Simple date add UDF.
 * Would use the Hive standard function, but that assumes a
 * date format of "YYYY-MM-DD", and we would prefer "YYYYMMDD"
 * and it is too awkward to include lots of substring functions in our hive
 */
public class AddDaysUDF extends UDF {
    private static final Logger LOG = Logger.getLogger(AddDaysUDF.class);
    private static final DateTimeFormatter YYYYMMDD = org.joda.time.format.DateTimeFormat.forPattern("YYYYMMdd");

    public String evaluate(String dateStr, int numDays) {
        DateTime dt = YYYYMMDD.parseDateTime(dateStr);
        DateTime addedDt = dt.plusDays(numDays);
        String addedDtStr = YYYYMMDD.print(addedDt);

        return addedDtStr;
    }
}
