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

/**
 * Given two dates in YYYYMMDD,
 * return the number of days between
 * midnight on each day..
 * <p/>
 * day_diff( "20120701", "20120702") == 1
 * day_diff( "20120701", "20120701") == 0
 */
@Description(
        name = "day_diff",
        value = " The difference in days of two YYYYMMDD dates"
)
public class DayDiffUDF extends UDF {
    private static final Logger LOG = Logger.getLogger(DayDiffUDF.class);
    private static final DateTimeFormatter YYYYMMDD = org.joda.time.format.DateTimeFormat.forPattern("YYYYMMdd");

    public Integer evaluate(String date1Str, String date2Str) {
        DateTime dt1 = YYYYMMDD.parseDateTime(date1Str);
        DateTime dt2 = YYYYMMDD.parseDateTime(date2Str);


        int dayDiff = Days.daysBetween(dt1, dt2).getDays();

        return dayDiff;
    }
}
