/*	Author Chris IOAKIM
 	dated 02/12/2001
 	class to read in dates and determine if they are valid and produce outputs
*/

public class newDate

{
	
	/* sets up an array wih all the months stored in , for retrieval within the program */
	public final static String [] Month = {" "," January "," February "," March ", " April "," May "," June "," July "," August "," September "," October "," November "," December "};
	
	/* sets up an array with the days for retreival within the program */
	public final static String [] Day = {" Sunday "," Monday "," Tuesday "," Wednesday "," Thursday "," Friday "," Saturday "};
	
	/* sets up an array with the valus of the dates. Mostly used within the julian calendar */
	
	public final static int [] Dates1 = {0,31,28,31,30,31,30,31,31,30,31,30,31};
	public final static int [] Dates2 = {0,31,29,31,30,31,30,31,31,30,31,30,31};
	
	/* sets up the variables to be used within the newDate class */
	public int day;
	public int month;
	public int year;
	public int day1;
	public int day2;
	public int month1;
	public int month2;
	public int year1;
	public int year2;
	
	/* values to be used as temp storage */
	public int tempday = 0; /* used in the julian calender */
	public int tempmonth = 0; /* used in the julian calender */
	public int tempday2 = 0; /* used in the Datename string */
	public double dtemp;
	public int d;
	public int M;
	public int D;
	public int C;
	public int Y; /* used in Zellars formula */
	public int yeargap, yeargap1, yeargap2; /* used in the days elasped to check for leap years */
	public int tempyear = 0; /* used in the leapyear */
	public int tempyear1;
	public String tempyear2; /* used in the DateName String */
	public String Julian1;
	public String JulianDate1, JulianDate2; /* used to output the Julian date for each date */
	public String wholedate; // used to produce the complete date with the day included
	public String leap1; // used to display if it's a leap year or not
	public int totallapse;  
	public int timelapse1;
	public int timelapse2; /* used to calculate the numbers of days between */
	public String timelapse; /* used to output the total number of days between two dates */	
	public String subyear;
	public String days1, days2;
	

	/* Constructors */
	
	public newDate(){}   /* defaullt constructor */
	
	
	public newDate(int day1 , int month1 , int year1 , int day2, int month2 , int year2 )
	{
		setDaysElapsed(day1,month1,year1,day2,month2,year2);
	}	
	
	
	/* Methods */
	
		
	
	public void setDaysElapsed(int day1, int month1, int year1, int day2 , int month2, int year2)		
	{
		day = day1;
		month = month1;
		year = year1;
		if (validDate(day,month, year))
		{
			dateName(day, month,year);
			days1 = wholedate;
			julianDay(day,month,year);
			JulianDate1 = Julian1;
			timelapse1 = tempday + year1;
		}
		else
		{
			System.out.println("An incorrect date has been set ");
		}	
		
		day = day2;
		month = month2;
		year = year2;
		if (validDate(day,month, year))
		{
			dateName(day, month,year);
			days2 = wholedate;
			julianDay(day,month,year);
			JulianDate2 = Julian1;
			timelapse2 = tempday + year1;
		}
		else
		{
			System.out.println("An incorrect date has been set ");
		}		
		
		
		if (timelapse1<=timelapse2) // checks if the first date is earlier than the secobd date 
		{
			if (year1 < year2) // checks to see if there is a gap in the years
			{
				yeargap = year2 - year1;// used to identify if a leap year exists between two dates
				yeargap2 = yeargap1 / 4;
				yeargap1 = ((yeargap-yeargap2) * 365)+(yeargap2*366); 
			}
			else
			{
				yeargap1 = 0;
			}		
			totallapse = 0;		
			totallapse = (timelapse2 - timelapse1) + yeargap1;
			timelapse = ("The number of days between the first date and the second is " + totallapse  + " days");
		}
		else
		{
			timelapse = ("The first date was greater than the second date");
		}
		
	
	}// ends daysElapsed	
	
	
	
	public boolean validDate ( int day, int month, int year ) 
	{
		if (((day<0)||(day>31)||((month<1)||(month>12))))
		{
			return false;
		}
		else if (((day<0)||(day>30))||(month==4)||(month==6)||(month==9)||(month==11))
		{
			return false;
		}		
		
		else if (((day >= 1) || (day <=29)) && ( month == 2) && ( tempyear == 0)) // tempyear set to zero if the year is a leap year
		{
			return true;
		}
		
		else if (((day >=1) || (day <=28)) && ( month == 2) && ( tempyear == 1)) // tempyear set to one if the year is not a leap year	
		{
			return true;
		}

		else if (year<0)
		{
			return false;
		}	
		else 
		{
			return true;
		}	
		
	} // ends ValidDate
	
	
		
	public boolean leapYear (int year)
	{	
		
		if (((year%4)==0)&&((year%100)!=0))
		{
			tempyear = 0;
			return true;
		}
		else if ((year%400)==0)
		{
			tempyear = 0;
			return true;
		}
		else 	
		{
			tempyear = 1;
			return false;
		}	
	} // ends leap year
	
	
		
	public void julianDay(int day,int month,int year)
	{
		
		if (validDate(day, month, year))
		{	
			if(leapYear(year))
			{
				
				leap1 = (" A leap year has been entered ");
				System.out.println("The year " + year + " is leap year ");
			}
			else
			{
			
				leap1 = (" The year entered is not a leap year ");
				System.out.println("The year " + year + " is not a leap year ");
			}	
			
			if (tempyear ==1)
			{
				tempmonth = 0;
				for (int i=0;i<month;i++)
				{
					tempmonth =  tempmonth + (Dates1[i]);
				}
				
				tempday = day + tempmonth;
				Julian1 = ("Julian date is " + tempday + " of year " + year);
			}
			else 
			{
				tempmonth = 0;
				for (int i=0; i<month;i++)
				{
					tempmonth = tempmonth + (Dates2[i]);
				}
			
				tempday = day + tempmonth;
				Julian1 = ("Julian date is " + tempday + " of year " + year);
			}
		}
		else
		{
			System.out.println ("The date entered was incorrect");	
		}
		
	}// ends Julian 	
	
	
	
	public void dateName (int day, int month,int year)
	{
		if (validDate(day,month,year))
		{
			D = day;
			if (month < 3)
			{
				M = month +10;
				Y = (year - 1)%100;
				C = (year -1 )/100;
			}
			else
			{
				M = month - 2;
				Y = year%100;
				C = year/100;
			}
			
			int d = (700 + (( (26*M)-2)/10) + D + Y + Y/4 + C/4 - (2*C))%7;
					
			wholedate = ( Day[d] + day + Month[month] + year);
		
				
			
			
		}
		else 
		{
			System.out.println("An incorrect date has been entered");
		}
	} // ends dateName
	
	
	
	/* get methods  */
	
	public String getLeapYear()
	{
		return leap1;
	}
	
	public String getJulianDay1()
	{
		return JulianDate1;
	}
	
	public String getJulianDay2()
	{
		return JulianDate2;
	}
	
	public String getDateName1()
	{
		return days1;
	}
	
	public String getDateName2()
	{
		return days2;
	}
	
	public String getDaysElapsed()
	{
		return timelapse;
	}
	
} /* ends the class */