/**
* Creates a new date by adding the specified number of months to the base date.
*
* <p>If the base date is close to the end of the month, the day on the result may be adjusted
* slightly: 31 May + 1 month = 30 June.
*
* @param months the number of months to add (can be negative).
* @param base the base date.
* @return a new date.
*/
public static SerialDate addMonths(final int months, final SerialDate base) {
final int yy = (12 * base.getYYYY() + base.getMonth() + months - 1) / 12;
final int mm = (12 * base.getYYYY() + base.getMonth() + months - 1) % 12 + 1;
final int dd = Math.min(base.getDayOfMonth(), SerialDate.lastDayOfMonth(mm, yy));
return SerialDate.createInstance(dd, mm, yy);
}
/**
* Creates a new date by adding the specified number of years to the base date.
*
* @param years the number of years to add (can be negative).
* @param base the base date.
* @return A new date.
*/
public static SerialDate addYears(final int years, final SerialDate base) {
final int baseY = base.getYYYY();
final int baseM = base.getMonth();
final int baseD = base.getDayOfMonth();
final int targetY = baseY + years;
final int targetD = Math.min(baseD, SerialDate.lastDayOfMonth(baseM, targetY));
return SerialDate.createInstance(targetD, baseM, targetY);
}
/**
* Returns the date that falls on the specified day-of-the-week and is CLOSEST to the base date.
*
* @param targetDOW a code for the target day-of-the-week.
* @param base the base date.
* @return the date that falls on the specified day-of-the-week and is CLOSEST to the base date.
*/
public static SerialDate getNearestDayOfWeek(final int targetDOW, final SerialDate base) {
// check arguments...
if (!SerialDate.isValidWeekdayCode(targetDOW)) {
throw new IllegalArgumentException("Invalid day-of-the-week code.");
}
// find the date...
final int baseDOW = base.getDayOfWeek();
int adjust = -Math.abs(targetDOW - baseDOW);
if (adjust >= 4) {
adjust = 7 - adjust;
}
if (adjust <= -4) {
adjust = 7 + adjust;
}
return SerialDate.addDays(adjust, base);
}
/**
* Returns the earliest date that falls on the specified day-of-the-week and is AFTER the base
* date.
*
* @param targetWeekday a code for the target day-of-the-week.
* @param base the base date.
* @return the earliest date that falls on the specified day-of-the-week and is AFTER the base
* date.
*/
public static SerialDate getFollowingDayOfWeek(final int targetWeekday, final SerialDate base) {
// check arguments...
if (!SerialDate.isValidWeekdayCode(targetWeekday)) {
throw new IllegalArgumentException("Invalid day-of-the-week code.");
}
// find the date...
final int adjust;
final int baseDOW = base.getDayOfWeek();
if (baseDOW > targetWeekday) {
adjust = 7 + Math.min(0, targetWeekday - baseDOW);
} else {
adjust = Math.max(0, targetWeekday - baseDOW);
}
return SerialDate.addDays(adjust, base);
}
/**
* Converts the date to a string.
*
* @return a string representation of the date.
*/
@Override
public String toString() {
return getDayOfMonth() + "-" + SerialDate.monthCodeToString(getMonth()) + "-" + getYYYY();
}
/**
* Rolls the date forward to the last day of the month.
*
* @param base the base date.
* @return a new serial date.
*/
public SerialDate getEndOfCurrentMonth(final SerialDate base) {
final int last = SerialDate.lastDayOfMonth(base.getMonth(), base.getYYYY());
return SerialDate.createInstance(last, base.getMonth(), base.getYYYY());
}
/**
* Creates a new date by adding the specified number of days to the base date.
*
* @param days the number of days to add (can be negative).
* @param base the base date.
* @return a new date.
*/
public static SerialDate addDays(final int days, final SerialDate base) {
final int serialDayNumber = base.toSerial() + days;
return SerialDate.createInstance(serialDayNumber);
}
