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*/

package com.google.refine.expr.functions.date;

import java.util.Calendar;
import java.util.Properties;

import org.json.JSONException;
import org.json.JSONWriter;

import com.google.refine.expr.EvalError;
import com.google.refine.grel.ControlFunctionRegistry;
import com.google.refine.grel.Function;

public class Inc implements Function {

    public Object call(Properties bindings, Object[] args) {
        if (args.length == 3 && 
                args[0] != null && args[0] instanceof Calendar && 
                args[1] != null && args[1] instanceof Number && 
                args[2] != null && args[2] instanceof String) {
            Calendar date = (Calendar) args[0];
            int amount = ((Number) args[1]).intValue();
            String unit = (String) args[2];
            
            date.add(getField(unit), amount);
            
            return date; 
        }
        return new EvalError(ControlFunctionRegistry.getFunctionName(this) + " expects a date, a number and a string");
    }

    private int getField(String unit) {
        if ("hours".equals(unit) || "hour".equals(unit) || "h".equals(unit)) {
            return Calendar.HOUR;
        } else if ("days".equals(unit) || "day".equals(unit) || "d".equals(unit)) {
            return Calendar.DAY_OF_MONTH;
        } else if ("years".equals(unit) || "year".equals(unit)) {
            return Calendar.YEAR;
        } else if ("months".equals(unit) || "month".equals(unit)) { // avoid 'm' to avoid confusion with minute
            return Calendar.MONTH;
        } else if ("minutes".equals(unit) || "minute".equals(unit) || "min".equals(unit)) { // avoid 'm' to avoid confusion with month
            return Calendar.MINUTE;
        } else if ("weeks".equals(unit) || "week".equals(unit) || "w".equals(unit)) {
            return Calendar.WEEK_OF_MONTH;
        } else if ("seconds".equals(unit) || "sec".equals(unit) || "s".equals(unit)) {
            return Calendar.SECOND;
        } else {
            throw new RuntimeException("Unit '" + unit + "' not recognized.");
        }
    }
    
    public void write(JSONWriter writer, Properties options) throws JSONException {
        writer.object();
        writer.key("description"); writer.value("Returns a date changed by the given amount in the given unit of time");
        writer.key("params"); writer.value("date d, number value, string unit (default to 'hour')");
        writer.key("returns"); writer.value("date");
        writer.endObject();
    }
}

@@ -1574,16 +1574,39 @@
 lendar;%0A
+import java.util.Date;%0A
 import j
@@ -1626,16 +1626,16 @@
 erties;%0A
-
 %0Aimport 
@@ -1989,24 +1989,25 @@
  != null && 
+(
 args%5B0%5D inst
@@ -2021,16 +2021,44 @@
 Calendar
+ %7C%7C args%5B0%5D instanceof Date)
  && %0A   
@@ -2212,30 +2212,300 @@
 date
- = (Calendar) args%5B0%5D;
+;%0A            if (args%5B0%5D instanceof Calendar) %7B%0A                date = (Calendar) ((Calendar) args%5B0%5D).clone(); // must copy so not to modify original%0A            %7D else %7B%0A                date = Calendar.getInstance();%0A                date.setTime((Date) args%5B0%5D);%0A            %7D%0A            
 %0A   

Make copy of Calendar object before modifying it. Also handle Date type.