//
// Original author: Gordon Griesel
//            Date: Fall 2024
//         Purpose: Calculate days between dates
//
// Days between dates is calculated by incrementing the earlier date
// one day at a time until it reaches the later date, and counting
// the increments.
//
// To be a leap year, the year number must be divisible by four – except for
// end-of-century years, which must be divisible by 400. This means that the
// year 2000 was a leap year, although 1900 was not. 2024, 2028, 2032 and
// 2036 are all leap years.
//
//
#include <iostream>
#include <iomanip>
#include <cstring>
using namespace std;

const char mname[][16] = {"Jan","Feb","Mar","Apr","May","Jun",
							"Jul","Aug","Sep","Oct","Nov","Dec"};
const int days[] = {31,28,31,30,31,30,31,31,30,31,30,31};

class Date
{
	private:
		int month;
		int day;
		int year;
	public:
	Date() {
		//The default constructor is not used.
	}
	Date(const char *date)
	{
		//date format: "mm-dd-yyyy"
		//Use it like this: Date d1("11-05-2024");
		month = (date[0]-'0')*10 + date[1]-'0';
		day   = (date[3]-'0')*10 + date[4]-'0';
		year  = (date[6]-'0')*1000 + (date[7]-'0')*100 +
				(date[8]-'0')*10 + (date[9]-'0');
	}
	Date operator++()
	{
		//prefix (pre increment)
		day += 1;
		return *this;
	}
	Date operator++(int)
	{
		//postfix (post increment)
		Date tmp;
		day += 1;
		return tmp;
	}
	bool operator==(const Date &d)
	{
		return (day == d.day && month == d.month && year == d.year);
	}
	friend ostream &operator<<(ostream &, const Date &);
};

ostream &operator<<(ostream &strm, const Date &obj)
{
	strm << mname[obj.month-1] << " " << setw(2) << obj.day << ", " << obj.year;
	return strm;
}

//function prototypes
int twoDates(const char *d1, const char *d2);
int daysBetweenDates(Date d1, Date d2);

//some test data
char testdates[][16] = {
	"11-05-2024", "11-05-2024",  //from today until today
	"11-05-2024", "11-06-2024",  //from today until tomorrow
	"11-01-2024", "11-30-2024",  //from nov-1 to nov-30
	"11-01-2024", "12-01-2024",  //from nov-1 to dec-1
	"01-01-2024", "01-01-2025",  //a whole year
	"01-01-2025", "01-01-2026",  //another whole year
	"",           ""
};



// main function is here
//========================================================
int main()
{
	cout << "\nCalculate days between dates.\n" << endl;
	char d1[100], d2[100];
	int noverflows = 0;
	int i = 0;
	while (strlen(testdates[i*2]) > 0) {
		strcpy(d1, testdates[i*2+0]);
		strcpy(d2, testdates[i*2+1]);
		cout << "Days between " << (Date)d1 << " and " << (Date)d2 << " is: ";
		//cout << flush;
		int count = twoDates(d1, d2);
		cout << count << endl;
		if (count >= 4000000)
			++noverflows;
		++i;
	}
	if (noverflows)
		cout << noverflows << " errors occured." << endl;
	cout << endl;
	return 0;
}

// Do not modify this function.
int twoDates(const char *d1, const char *d2)
{
	Date date1(d1);
	Date date2(d2);
	//cout << "Days between " << date1 << " and " << date2 << " is: " << flush;
	int count = daysBetweenDates(date1, date2);
	//cout << count << endl;
	return count;
}	

// Do not modify this function.
int daysBetweenDates(Date d1, Date d2)
{
	// Start the count at 0.
	// Example: The days between Thursday and Friday
	//          will be one day not two days.
	int count = 0;
	while (!(d1 == d2)) {
		++d1;
		++count;
		//safety exit
		if (count >= 40000000)
			break;
	}
	return count;
}