/**
 * Write a description of class Date here.
 *
 * @author (your name)
 * @version (a version number or a date)
 */
public class Date
{
    private int _day;
    private int _month;
    private int _year;
    private final int JAN=31;
    private final int FEB=28;
    private final int MAR=31;
    private final int APR=30;
    private final int MAY=31;
    private final int JUN=30;
    private final int JUL=31;
    private final int AUG=31;
    private final int SEP=30;
    private final int OCT=31;
    private final int NOV=30;
    private final int DEC=31;

    //constructors:
    /**
     * creates a new Date object
     * @param _day the day in the month(1-31)
     * @param _month the month in the year
     * @param _year the year (in 4 digits)
     */
    public Date(int day, int month, int year) {
        _day = day;
        _month = month;
        _year = year;

        if(checkDate(this._day,this._month,this._year)==false)
        {
            _day=1;
            _month=1;
            _year=2000;
        }

    } //
    /**
     * Copy Constructor
     * @param passport to be copied
     */
    public Date(Date other){
        this._day = other._day;
        this._month = other._month;
        this._year = other._year;
    }

    /** gets the year */
    public int getYear(){
        return _year;
    }

    /** gets the month */
    public int getMonth(){
        return _month;
    }

    /** gets the Day */
    public int getDay(){
        return _day;
    }

    /** sets the year
     * @param yearToSet the value to be set
     */
    public void setYear(int yearToSet){
        if(checkDate(_day, _month, yearToSet)==true)
            _year = yearToSet;
    }

    /** set the month
     * @param monthToSet the value to be set
     */
    public void setMonth(int monthToSet){
        if(checkDate(_day, monthToSet, _year)==true)
            _month = monthToSet;
    }

    /** sets the day
     *  @param dayToSet the value to be set
     */
    public void setDay(int dayToSet){
        if(checkDate(dayToSet, _month, _year)==true)
            _day = dayToSet;
    }

    private boolean checkDate(int day, int month, int year) { //Check Date
        _day = day;
        _month = month;
        _year = year;
        int _check=0;
        if((_day>31||_day<1)||(_month>12||_month<1)||(_year>9999||_year<1000))
            _check=1;
        else
        {
            if(_month==2) //Check for FEBRUARY
            {
                if(_day>29 || _day<28)
                    _check=1;
                else
                {
                    if(_year%4==0)
                    {
                        if(_year%100>0 && _year%400>0)
                            _check=1;
                    }
                }
            }

            if((_month==4 || _month==6 || _month==9 || _month==11) && _day>30) //Check for 30days monthes
                _check=1;
        }
        if(_check==1)
            return false;
        else
            return true;
    }

    public boolean equals(Date other){ //Check if same
        if((this._day == other._day) && (this._month == other._month) && (this._year == other._year))
            return true;
        return false;
    }

    /**
     * checks if this date comes before a given date
     * @param other the given date
     * @retun true iff this date comes before other
     */
    public boolean before(Date other) {
        if (_year < other._year)
            return true;
        if (_year == other._year) {
            if (_month < other._month)
                return true;
            if (_month == other._month && _day < other._day)
                return true;
        }
        return false;
    }

    /**
     * checks if this date comes after a given date
     * @param other the given date
     * @retun true iff this date comes before other
     */
    public boolean after(Date other) {
        if(before(other)==false)
            return true;
        return false;
    }

    /**
     * checks the difference in days between dates
     * @param other the given date
     * @retun the difference in days between dates
     */
    public int difference(Date other) {
        int _sumDt=calculateDate(_day,_month,_year); //this date
        int _sumDo=calculateDate(other._day,other._month,other._year); //other date
        if (_sumDt>_sumDo)
            return _sumDt-_sumDo;
        else
            return _sumDo-_sumDt;
    }

    /**
     * Given tomorrow date
     * @retun tomorrow date
     */

    public Date tomorrow()
    {
        if(checkDate(_day+1,_month,_year)==true)
        {
                Date dateN = new Date(_day+1,_month,_year);
            return dateN;
        }
        else
        if(checkDate(1,_month+1,_year)==true)
        {
                Date dateN = new Date(1,_month+1,_year);
            return dateN;
        }
        else
        if(checkDate(1,1,_year+1)==true)
        {
                Date dateN = new Date(1,1,_year+1);
            return dateN;
        }
        else
        {
                Date dateN = new Date(_day+1,_month,_year);
            return dateN;
        }
    }

    /**
     * @return String that represents this date
     * in the following format:
     * day.month.year (30/9/1917)
     */
    public String toString() {
        String s="";
        if (_day<10)
            s+="0"+_day+"/";
        else
            s+=_day+"/";
        if (_month<10)
            s+="0"+_month+"/";
        else
            s+=_month+"/";
        s+=_year;

        return s;
    }
    // computes the day number since the beginning of the Christian counting of years
    private int calculateDate ( int day, int month, int year) {
        if (month < 3) {
            year--;
            month = month + 12;
        }
        return 365 * year + year/4 - year/100 + year/400 + ((month+1) * 306)/10 + (day - 62);
    }
}