// Programmer:  Rance Cleaveland
// Date:		9 Oct. 2006
//
// This class implements simple operations on dates.

public class Date {
	
	public static int DEFAULT_DAY = 1;				// Default day value
	public static int DEFAULT_MONTH = 1;			// Default month value
	public static int DEFAULT_YEAR = 1900;  		// Default year value
	public static String DEFAULT_SEPARATOR = "/";	// Default separator
	public static String DEFAULT_NOTE = "";			// Default note
	
    private int day   = DEFAULT_DAY;				// Day part of date
    private int month = DEFAULT_MONTH;				// Month part of date
    private int year  = DEFAULT_YEAR;				// Year part of date
    private String separator = DEFAULT_SEPARATOR;	// Separator for date
    private String note = DEFAULT_NOTE;				// Comment field for date
    
    // Default constructor
    
    Date () {
    }
    
    // Another constructor.  Consistency check ensures only valid data returned
    // (erroneous arguments lead to default constructor being applied)
    
    Date (int newDay, int newMonth, int newYear){
    	day = newDay;
    	month = newMonth;
    	year = newYear;
    	if (!(isValid (this))) {
    		System.out.println ("Invalid arguments to Date constructor:  " + newDay + "," + newMonth + "," + newYear);
    		restoreDefaults ();
    	}
    }
    
    // Copy constructor
    
    Date (Date d) {
    	day = d.day;
    	month = d.month;
    	year = d.year;
    	separator = d.separator;
    	note = d.note;
    }
    
    // restoreDefaults restores default values for all fields
    
    public void restoreDefaults () {
    	day = DEFAULT_DAY;
    	month = DEFAULT_MONTH;
    	year = DEFAULT_YEAR;
    	separator = DEFAULT_SEPARATOR;
    	note = DEFAULT_NOTE;
    }
    
    // isValid determines if Date is valid (year is non-negative, month falls in 1-12,
    // and day is correct).
    
    public static boolean isValid (Date d) {
    	if (d.year < 0) return false;
    	else if (d.month < 1) return false;
    	else if (d.month > 12) return false;
    	else if (d.day < 1) return false;
    	else if (d.day > d.numDaysInMonth ()) return false;
    	else return true;
    }
    
    // The method for converting dates to strings
    
    public String toString () {
    	return (month + separator + day + separator + year);
    }
    
    // Method for printing dates to System.out

	public void print () {
		System.out.print (toString ());
	}
	
	// Method for printing dates plus surrounding text
	
	public void print (String pre, String post){
		System.out.print (pre);
		print ();
		System.out.print (post);
	}

    // Method for printing dates followed by carriage return

	public void println () {
		print ();
		System.out.println ();
	}
	
	// Method for printing dates plus surrounding text, followed by return
	
	public void println (String pre, String post) {
		print (pre, post);
		System.out.println ();
	}
    
    // "incrementYear" increments the year.
    
    public void incrementYear () {
    	year++;
    }
    
    // "incrementMonth" increments the month.
    
    public void incrementMonth () {
    	if (month < 12)
    		month++;
    	else {
    		month = 1;
    		year++;
    	}
    }
    
    // "setYear" allows the year to be set to a give value
    
    public void setYear (int newYear) {
    	int oldYear = year;
    	year = newYear;
    	if (!(Date.isValid (this))){
    		System.out.println ("Invalid year argument to setYear:  " + newYear);
    		year = oldYear;  // Restore old year value
    	}
    }
    
    // "setMonth" allows the month to be set; an error is reported
    // if the month is invalid
    
    public void setMonth (int newMonth) {
    	if ((1 <= newMonth) && (newMonth <= 12))
    		month = newMonth;
    	else
    		System.out.println ("Bad argument to setMonth:  " + newMonth);
    }
    
    // "isLeapYear" returns true if the year is a leap year.
    
    public boolean isLeapYear () {
    	return ((year % 4) == 0 && ((year % 100 != 0) || (year % 400 == 0)));
    }
    
    // "numDaysInMonth" returns the number of days in the current month
    
    private int numDaysInMonth () {
    	if (month == 1)
    		return 31;
    	else if (month == 2) {
    		if (isLeapYear ())
    			return 29;
    		else return 28;
    	}
    	else if (month == 3)
    		return 31;
    	else if (month == 4)
    		return 30;
    	else if (month == 5)
    		return 31;
    	else if (month == 6)
    		return 30;
    	else if (month == 7)
    		return 31;
    	else if (month == 8)
    		return 31;
    	else if (month == 9)
    		return 30;
    	else if (month == 10)
    		return 31;
    	else if (month == 11)
    		return 30;
    	else // (month == 12)
    		return 31;
    }
    
    
    // "setDay" allows the day to be set; an error is reported if the
    // day value is invalid for the given month
    
    public void setDay (int newDay) {
    	if (numDaysInMonth () >= newDay)
    		day = newDay;
    	else
    		System.out.println ("Invalid number of days (month = " + month +"):  " + newDay);
    }
    
    // "addDays" adds given number of days to date (must be positive)
    
    public void addDays (int future) {
    	if (future < 0)
    		System.out.println("Invalid argument to addDays:  " + future);
    	else {
    		int daysLeft = day + future;
    		while (daysLeft > numDaysInMonth()) {
    			daysLeft -= (numDaysInMonth ());
    			incrementMonth ();
    		}
    		day = daysLeft;
    	}
    }
    
    // "getDay" returns the day
    
    public int getDay () {
    	return day;
    }
    
    // "getMonth" returns the month
    
    public int getMonth () {
    	return month;
    }
    
    // "getYear" returns the year
    
    public int getYear () {
    	return year;
    }
    
    // "isValentinesDay" returns true if the date is Valentines Day
    
    public boolean isValentinesDay () {
    	return ((month == 2) && (day == 14));
    }
    
    // "equals" computes an equality function on dates
    
    public boolean equals (Date d) {
    	return (day == d.day && month == d.month && year == d.year);
    }
    
    // "isBefore" returns true if the date is before the inputted date
    
    public boolean isBefore (Date d) {
    	if (year < d.year) return true;
    	else if (year == d.year) {
    		if (month < d.month) return true;
    		else if ( (month == d.month) && (day < d.day) )
    			return true;
    		else return false;
    	}
    	else return false;
    }
}