Application: gvSIG desktop

package org.gvsig.expressionevaluator.impl.function.date;

import java.time.LocalDateTime;

import java.time.ZoneId;

import java.time.temporal.ChronoUnit;

import java.util.Date;

import org.apache.commons.lang3.Range;

import static org.gvsig.expressionevaluator.ExpressionBuilder.FUNCTION_DATEADD;

import org.gvsig.expressionevaluator.Interpreter;

import org.gvsig.expressionevaluator.spi.AbstractFunction;

public class DateAddFunction extends AbstractFunction {

    public DateAddFunction() {

        super("Date", FUNCTION_DATEADD,Range.is(3),

            "Adds a time/date interval to a date and then returns the date",

            FUNCTION_DATEADD+"({{interval}}, number, date)",

            new String[]{

                "interval - a string with the value year,month,day,hour,minute,second or millisecond.",

                "number - a number in the unit specified with interval parameter",

                "date - a Date",

            },

            "Date"

        );

    }

    @Override

    public boolean allowConstantFolding() {

        return true;

    }

    @Override

    public Object call(Interpreter interpreter, Object[] args) {

        String interval = this.getStr(args, 0);

        long number = this.getLong(args,1);

        LocalDateTime date = this.getLocalDateTime(args,2);

        switch(interval.toLowerCase()) {

            case "millisecond":

            case "ms":

                date = date.plus(number, ChronoUnit.MILLIS);

                break;

            case "second":

            case "ss":

            case "s":

                date = date.plus(number, ChronoUnit.SECONDS);

                break;

            case "minute":

            case "mi":

            case "n":

                date = date.plus(number, ChronoUnit.MINUTES);

                break;

            case "hour":

            case "hh":

                date = date.plus(number, ChronoUnit.HOURS);

                break;

            case "day":

            case "dy":

            case "y":

                date = date.plus(number, ChronoUnit.DAYS);

                break;

            case "month":

            case "mm":

            case "m":

                date = date.plus(number, ChronoUnit.MONTHS);

                break;

            case "year":

            case "yyyy":

            case "yy":

                date = date.plus(number, ChronoUnit.YEARS);

                break;

            default:

                throw new IllegalArgumentException("Unsupported interval '"+interval+"'.");

        } 

        return Date.from( date.atZone( ZoneId.systemDefault()).toInstant());

    }

}