//-------------------------------------------------------------
// Example to illustrate user-defined functions
//-------------------------------------------------------------

#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;

// ------------------------------------------------------------
// LeapYear determines whether a year is or is not a leap year
// ------------------------------------------------------------
// Accepts:   number representing a year
// Returns:   a true or false calculation
// ------------------------------------------------------------

bool LeapYear (int year)
{
	int rem;
	rem = year % 4;

	if (rem == 0)
		return true;
	else return false;
}

//-------------------------------------------------------------
// DaysInMonth determines the number of days of the month
//-------------------------------------------------------------
// Accepts:  number (1 - 12) representing month
// Returns:  number of days in that month
//-------------------------------------------------------------

int DaysInMonth (int monthnum, int year)
{
    int numdays;  // temp variable for days in month

    switch (monthnum)
    {
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:   numdays = 31;  break;
        case 2:    if (LeapYear(year) == true)
                      numdays = 29;
                   else
                      numdays = 28;
                   break;
        case 4:
        case 6:
        case 9:
        case 11:   numdays = 30;  break;
    }

    return numdays;
}

//-------------------------------------------------------------
// DisplayMonthName displays the month name to standard output
//-------------------------------------------------------------
// Accepts:  number (1 - 12) representing month
// Returns:  nothing
//-------------------------------------------------------------

void DisplayMonthName (int monthnum)
{
    switch (monthnum)
    {
        case 1:  cout << "January";  break;
        case 2:  cout << "February";  break;
        case 3:  cout << "March";  break;
        case 4:  cout << "April";  break;
        case 5:  cout << "May";  break;
        case 6:  cout << "June";  break;
        case 7:  cout << "July";  break;
        case 8:  cout << "August";  break;
        case 9:  cout << "September";  break;
        case 10:  cout << "October";  break;
        case 11:  cout << "November";  break;
        case 12:  cout << "December";  break;
    }
}


//-------------------------------------------------------------
// DisplayFirstLine displays the first week in the output
//-------------------------------------------------------------
// Accepts:  number (1 - 6) representing days in first week of output
// Returns:  nothing
//-------------------------------------------------------------

void DisplayFirstLine (int startdayofweek)
{
   int i;
   
   cout << "\n";
   for(i = 0; i < startdayofweek; i ++)
       cout << "     ";
   for(i = 1; i <= (7 - startdayofweek); i ++)
       cout << setw(5) << i;
}

//-------------------------------------------------------------
// DisplayFullWeek displays the full week of output
//-------------------------------------------------------------
// Accepts:  number (resulting start date of week)
// Returns:  nothing
//-------------------------------------------------------------

void DisplayFullWeek (int startdateofweek)
{
   int i;
   
   cout << "\n";
   for (i = startdateofweek; i <= (startdateofweek + 6); i ++)
        cout << setw(5) << i;
}

//-------------------------------------------------------------
// DisplayLastWeek displays the last week of output
//-------------------------------------------------------------
// Accepts:  numbers (start date of week and number of days in the month)
// Returns:  days of month
//-------------------------------------------------------------

void DisplayLastWeek (int startdateofweek, int numdaysinmonth)
{
   int i;

   cout << "\n";
   for (i = startdateofweek; i <= numdaysinmonth; i ++)
        cout << setw(5) << i;
}

int getFirstDay( int monthnum, int year )
{
	int mysteryInt, code, dayofmonth;

	mysteryInt = 8;
	mysteryInt += (mysteryInt / 4);

	switch( monthnum )
	{
		case 5:		code = 0; break;
		case 8:		code = 1; break;
		case 2:	
		case 3:	
		case 11:	code = 2; break;
		case 6:		code = 3; break;
		case 9:	
		case 12:	code = 4; break;
		case 4:	
		case 7:		code = 5; break;
		case 1:	
		case 10:	code = 6; break;
	}

	dayofmonth = mysteryInt + code + 1;
	if( dayofmonth > 7 )
		dayofmonth = dayofmonth % 7;
	return dayofmonth;
}

void leapYear( int year )
{
	int startYear, endYear, leapCount = 4;

	startYear = year;
	startYear /= 100;

	switch( startYear )
	{
		case 17:	leapCount = 5; break;
		case 18:	leapCount = 3; break;
		case 19:	leapCount = 1; break;
		case 21:	leapCount = 5; break;
		case 22:	leapCount = 3; break;
	}

	cout << "---------- DEBUG ----------" << endl;
	cout << "Leap Count: " << leapCount << endl;
	cout << "Start Year: " << startYear << endl;
	cout << "---------- DEBUG ----------" << endl;
}

//-------------------------------------------------------------
//  Main Function
//-------------------------------------------------------------

int main ( )
{

// --- Variables

    int monthnum,          // month number (1 - 12) entered by user
        startdateofweek,   //
        begdateofnextweek, //
        year,
        begdayofmonth,     //
        numdays;           // number of days in month

// --- Get Year and  month numbers from user

    cout << "\nEnter a year (1700-2299): ";
    cin >> year;
    cout << "\nEnter a month number (1-12): ";
    cin >> monthnum;

// --- Validate month number

    while (year < 1700 || year > 2299)
    {
       cout << "\n\n!!! Year number must be within the range of 1700 to 2299!!!";
       cout << "\n\nPlease re-enter year number: ";
       cin >> year;
    }

    while (monthnum < 1 || monthnum > 12)
    {
       cout << "\n\n!!! Month number must be in range 1 - 12 !!!";
       cout << "\n\nPlease re-enter month number: ";
       cin >> monthnum;
    }

// --- Get number of days in month
 
	begdayofmonth = getFirstDay( monthnum, year );
    numdays = DaysInMonth(monthnum, year);
	leapYear( year );

// --- Display output sentence 

    cout << endl;
    cout << "\t\t";
    DisplayMonthName (monthnum);
    cout << endl;
    cout << "   ---------------------------------";
    cout << endl;
    cout << "   Sun  Mon  Tue Wed  Thur Fri  Sat";
    cout << endl;
    cout << "   ---------------------------------";

    DisplayFirstLine(begdayofmonth);
     begdateofnextweek = 8 - begdayofmonth;
    DisplayFullWeek(begdateofnextweek);
     begdateofnextweek += 7;
    DisplayFullWeek(begdateofnextweek);
     begdateofnextweek += 7;
    DisplayFullWeek(begdateofnextweek);
     begdateofnextweek += 7;
  if(numdays - begdateofnextweek >= 7)
  {
   DisplayFullWeek(begdateofnextweek);
    begdateofnextweek += 7;
  }
    DisplayLastWeek(begdateofnextweek, numdays);
     begdateofnextweek += 7;
    cout << endl;
    cout << endl;

return 0;
}