Month.java

package marubinotto.util.time;

import java.util.Calendar;

import marubinotto.util.Assert;

/**
 * marubinotto.util.time.Month
 */
public class Month extends Interval {

	public Month() {
		this(DateTime.getCurrentTime());
	}

	public Month(DateTime dateTime) {
		super(getFirstInstantOfMonth(dateTime), getEndInstantOfMonth(dateTime));
	}

	public Month(int year, int month) {
		this(new DateTime(year, month, 1));
	}

	public int getYear() {
		return getFirstDay().getYear();
	}

	public int getMonth() {
		return getFirstDay().getMonth();
	}

	public int getDayCount() {
		return getLastDay().getDayOfMonth();
	}

	public String toString() {
		return "Month: " + getFirstDay().format("yyyy-MM");
	}

	public DateTime getFirstDay() {
		return getStartInstant();
	}

	public DateTime getLastDay() {
		return getEndInstant();
	}

	public DateTime[] getDays() {
		int dayCount = getDayCount();
		DateTime[] days = new DateTime[dayCount];
		DateTime firstDay = getFirstDay();
		days[0] = firstDay;
		for (int i = 1; i < dayCount; i++) {
			days[i] = firstDay.addDays(i);
		}
		return days;
	}

	public Month getLastMonth() {
		return new Month(getFirstDay().addMonths(-1));
	}

	public Month getNextMonth() {
		return new Month(getLastDay().addMonths(1));
	}

	// Utility methods

	public static DateTime getFirstInstantOfMonth(DateTime dateTime) {
		Assert.Arg.notNull(dateTime, "dateTime");
		return new DateTime(dateTime.getYear(), dateTime.getMonth(), 1);
	}

	public static DateTime getEndInstantOfMonth(DateTime dateTime) {
		Assert.Arg.notNull(dateTime, "dateTime");

		DateTime firstInstant = getFirstInstantOfMonth(dateTime);
		Calendar calendar = firstInstant.toCalendar();
		calendar.add(Calendar.MONTH, 1);
		calendar.add(Calendar.MILLISECOND, -1);
		return new DateTime(calendar);
	}
}