#include "Date.h"
Date::Date() {
   //constructor to assign todays date to date
   char data[9]; //holder for the date 
   _strdate_s(data); //gets the current date mm/dd/yy
   string date=data; //copy to a string for parsing
   month=stoi(date.substr(0,2)); //gets characters 0 and 1 of date and converts to int
   day=stoi(date.substr(3,2)); //gets characters 3 and 4 of date and converts to int
   year=stoi(date.substr(6,2))+2000; //gets characters 6 and 7 of date and converts to int
   if(leapYear()) days2[2]=29; else days2[2]=28;
   for(int m=0;m<13;m++) days[m]=days2[m]; 
}//constructor for today

static bool validDate(int m, int d, int y) {
   bool valid=true; //assume it is valid until found to be invalid
   if(y<1000) valid=false;
   if(m<1 || m>12) valid=false;
   if(leapYear(y)) days2[2]=29; else days2[2]=28;
   if(d<1 || d>days2[m]) valid=false;
   return valid; 
}//validDate

Date::Date(int m, int d, int y) {
   //constructor to assign values to month day and year 
   if(validDate(m,d,y)) {
      month=m;
      day=d;
      year=y;
   }
   else {
      month=day=1;
      year=1970; //Unix time starting point
   } //not valid: set to default valid date
   for(int m=0;m<13;m++) days[m]=days2[m]; 
} //constructor with assigned values

Date::Date(int julian) {
  //Fliegel-Van Flandern algorithm to convert Julian date to Gregorian number month, day, and year
  gregorian(julian,month,day,year); 
  if(leapYear()) days2[2]=29; else days2[2]=28;
  for(int m=0;m<13;m++) days[m]=days2[m]; 
}//Date Julian

Date::Date (string str) { //constructor for todays date as "mm/dd/year
  //Parse str by adding one char at a s time to the token until a "/" is encounter.
  //When "/" is encountered start the next token
  //int p=0;
  int count=0;
  int num[3];
  string token[3];
  int len=str.length();
  for(int p=0; p<len;p++) {
     if(str.substr(p,1)=="/") count++;
	 else token[count]+=str.substr(p,1);
  }//parse str to create array of tokens
  bool error=false;
  for(int p=0;p<3;p++) {
	  try {
		num[p]=stoi(token[p]);
	  }//try to convert to int
	 catch(invalid_argument&) {
		 num[p]=-1;
		 error=true;
	 } //catch
  }//each of the 3 tokens
  if(!error && validDate(num[0],num[1],num[2])) {
    month=num[0];
    day=num[1];
    year=num[2];
  } //no error
  else {
    month=day=1;
    year=1970; //Unix time starting point
  }  //not valid: set to default valid date 
  for(int m=0;m<13;m++) days[m]=days2[m]; 
}//constructor with string such as "10/31/2016"

Date Date::operator=(const Date& otherDate) {
   //assigns another instance of the date class to this.
   month=otherDate.month;
   day=otherDate.day;
   year=otherDate.year;
   return *this;  //allows date1=date=date3;
}//overloaded operator =

Date Date::operator+(int numDays) {
   //Adds the number of days to the Julian date.
   Date other(month,day,year); //make copy of the date
   int jd=other.julian();  //find the Julian date
   jd+=numDays; //add the number of days to the Julian date
   gregorian(jd,other.month,other.day,other.year); //Convert the Julian date back to Gregorian
   if(other.leapYear()) days2[2]=29; else days2[2]=28;
   for(int m=0;m<13;m++) other.days[m]=days2[m]; 
   return other;
} //operator +

int Date::dayofYear() const {
   //returns the day of the year, ie 2/1/???? is the 32 day of the year
   int total=day;
   for(int m=1;m<month;m++) total+=days[m];
   return total;
}//dayofYear

void gregorian(int julian, int &mth, int &d, int &y) {
  //Fliegel-Van Flandern algorithm to convert Julian date to Gregorian month, day, and year
  int p,q,r,s,t,u,v;
  p = julian + 68569;
  q = 4*p/146097;
  r = p - (146097*q + 3)/4;
  s = 4000*(r+1)/1461001;
  t = r - 1461*s/4 + 31;
  u = 80*t/2447;
  v = u/11;
  y = 100*(q-49)+s+v;
  mth = u + 2 - 12*v;
  d = t - 2447*u/80;
} //Gregorian

int Date::julian() const {
	int jd= day-32075+1461*(year+4800+(month-14)/12)/4+
		367*(month-2-(month-14)/12*12) /12-3*((year+4900+(month-14)/12)/100)/4;
	return jd;

}
bool Date::leapYear() const {
   bool leap=false;
   if(year%4==0) leap=true;
   if(year%100==0 && year%400!=0) leap=false;
   return leap;
}//leapYear

bool leapYear(int yr) {
   bool leap=false;
   if(yr%4==0) leap=true;
   if(yr%100==0 && yr%400!=0) leap=false;
   return leap;
}//leapYear

int Date::weekday() const {
   //returns 0 for Sunday, 1 for Monday, etc.
   static int t[] = { 0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4 };
   int y =year;
   y-= month < 3;
   return ( y + y/4 - y/100 + y/400 + t[month-1] + day) % 7;
}//weekday

int Date::getMonth() const { 
   //private variables cannot be accessed directly but require "getter" functions
   return month;
}//getMonth

int Date::getDay() const {
   return day;
}//

int Date::getYear() const {
   return year;
}//getYear

string Date::toString() const {
  stringstream oss;  //a stream to append the values
  oss<<month<<"/"<<day<<"/"<<year;
  return oss.str(); 
}

bool Date::operator==(const Date& otherDate) {
   return (month==otherDate.month && day==otherDate.day && year==otherDate.year);
}//operator ==

bool Date::operator<(const Date& otherDate) {
   //A date is less than another date if is earlier
   bool result=false; //assume false until proven true
   if(year<otherDate.year) result=true;
   else if(year==otherDate.year && month<otherDate.month) result=true;
   else if(year==otherDate.year && month==otherDate.month && day<otherDate.day) result=true;
   return result;
}//operator

bool Date::operator>(const Date& otherDate) {
   //Convert both dates to Julian and compare the Julian dates
   int jd1=julian();
   int jd2=otherDate.julian();
   return jd1>jd2;
}//operator

ostream& operator << (ostream &output, const Date &d) { 
   output << d.toString();
   return output; 
} // operator <<
istream& operator >> (istream &input, Date &d) { 
   string s;
   input >> s;
   Date other(s); //create a new Date
   d=other; //assign the new Date to d
   return input; 
 } // operator >>