/****************************************************************************************
*							Java日歷程序

*    作者：張亞航
*
*    完成時間：2008-5-22
*
*	 程序功能：
*    Control包中的ComputeDate類主要是用來計算每個月的第一天是星期幾以及每個月的總天數
*    
*    程序設計思想：
*    本程序的主要的思想是計算公元后某一年，根據MyDate對象中的year屬性，計算在這年之前的總天數
*    然后計算每個月的偏移量，
*    然后mod 7求余數來計算每個月第一天的偏移量
*
******************************************************************************************/


package control;
import java.util.*;
import model.MyDate;
public class ComputeDate 
{
	int i,day,year;
	int daysOfYear;
	long wholeDays = 0;
	int daysOfMonth = 0;
	
	/*******************計算在這年之前的總天數*************************/
	public long getWholeDays(MyDate date)
	{
		long dayCount=0;
		for(int yearCount=1;yearCount<date.getYear();yearCount++)
		{
			//System.out.print("aaaaaaaaaaaaaa"+date.getYear());
			if(isLeapYear(yearCount))
				daysOfYear=366;
			else
				daysOfYear=365;
			dayCount += daysOfYear;
		}
		return dayCount;
	}
	
	/*******************計算在這年每個月的偏移量*************************/
	public long getFirstDay(MyDate date)
	{
		int curYear = date.getYear();  //當前年份
		int curMonth = date.getMonth();//當前月份
		int flagDay = 0;               //該標記是個標記量，主要是當閏年的時候，則進行標記，很多偏移量根據這個變量來進行計算以區別閏年閏月
		wholeDays = getWholeDays(date);
		
		long firstDay = 0;
		if(isLeapYear(curYear))
		{
			flagDay = 1;
			//System.out.print("aaaaaaaaaaaaaa"+flagDay);
		}
		
		

		//計算某一個月份的偏移量
		switch(curMonth)
		{
		case 1 : firstDay = wholeDays%7;daysOfMonth=31; break;
		case 2 : wholeDays+=31;firstDay = wholeDays%7; daysOfMonth=28+flagDay; break;
		case 3 : wholeDays+=59+flagDay;firstDay = wholeDays%7; daysOfMonth=31; break;
		case 4 : wholeDays+=90+flagDay;firstDay = wholeDays%7; daysOfMonth=30; break;
		case 5 : wholeDays+=120+flagDay;firstDay = wholeDays%7; daysOfMonth=31; break;
		case 6 : wholeDays+=151+flagDay;firstDay = wholeDays%7; daysOfMonth=30; break;
		case 7 : wholeDays+=181+flagDay;firstDay = wholeDays%7; daysOfMonth=31; break;
		case 8 : wholeDays+=212+flagDay;firstDay = wholeDays%7; daysOfMonth=31; break;
		case 9 : wholeDays+=243+flagDay;firstDay = wholeDays%7; daysOfMonth=30; break;
		case 10: wholeDays+=273+flagDay;firstDay = wholeDays%7; daysOfMonth=31; break;
		case 11: wholeDays+=304+flagDay;firstDay = wholeDays%7; daysOfMonth=30; break;
		case 12: wholeDays+=334+flagDay;firstDay = wholeDays%7; daysOfMonth=31; break;
		}
		return firstDay;
	}
	
	//獲得該月份總天數
	public long getDaysOfMonth(MyDate date)
	{
		getFirstDay(date);
		return daysOfMonth;
	}
	
	/*******************判斷是否為閏年*************************/
	public boolean isLeapYear(int year)
	{
		if ((year %4 == 0) && (year % 100 != 0)||(year % 400 == 0))
			return true;
		else
			return false;
	}
}