///////////////////////////////////////////////////////////
// Softwarebauelemente II, Aufgabe O2.1
//
// author:			Stephan Brumme
// last changes:	February 26, 2001


#include "Date.h"
#include <iostream>

// we are using OS-specific date/time operations
#include <time.h>




// constructor, default value is 0/0/00 (invalid date !)
CDate::CDate(int nDay, int nMonth, int nYear)
{
	// store date
	m_nDay   = nDay;
	m_nMonth = nMonth;
	m_nYear  = nYear;
}


// attention ! this method is NOT part of CDate
ostream& operator<<(ostream &mystream, const CDate& date)
{
	return date.OutStream(mystream);
}


// used to perform proper display in derived classes
ostream& CDate::OutStream(ostream& mystream, bool bDebug) const
{
	if (!bDebug)
	{
		mystream << m_nDay << "." << m_nMonth << "." << m_nYear;
	}
	else
	{
		mystream << "DEBUG info for '" << ClassnameOf() << "'" << endl 
			<< "   m_nDay="   << m_nDay
			<<  "  m_nMonth=" << m_nMonth
			<<  "  m_nYear="  << m_nYear;
	}

	return mystream;
}


// return current date
CDate CDate::GetToday()
{
	CDate dtReturn;

	// the following code is taken from MSDN

	// use system functions to get the current date as UTC
	time_t secondsSince1970;
	time(&secondsSince1970);

	// convert UTC to local time zone
	struct tm *localTime;
	localTime = localtime(&secondsSince1970);

	// store retrieved date
	dtReturn.m_nDay   = localTime->tm_mday;
	dtReturn.m_nMonth = localTime->tm_mon + 1;
	dtReturn.m_nYear  = localTime->tm_year + 1900;

	return dtReturn;
}


// validate a date
bool CDate::IsValid() const
{
	// validate month
	if (m_nMonth < JANUARY || m_nMonth > DECEMBER)
		return false;

	// days per month, february ma(r)y vary !!!
	int nDaysPerMonth[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

	// adjust days of february
	if (IsLeapYear(m_nYear))
		nDaysPerMonth[FEBRUARY]++;

	// validate day
	if (m_nDay < 1 || m_nDay > nDaysPerMonth[m_nMonth])
		return false;

	// day and month are valid
	return true;
}


// determine whether it is a leap year
bool CDate::IsLeapYear(int nYear)
{
	// used to speed up code, may be deleted
	if (nYear % 4   != 0)
		return false;

	// algorithm taken from MSDN, just converted from VBA to C++ 
	if (nYear % 400 == 0)
		return true;
	if (nYear % 100 == 0)
		return false;
	if (nYear % 4   == 0)
		return true;

	// this line won't be executed because of optimization (see above)
	return false;
}


// copy constructor		
CDate& CDate::operator =(const CDate &date)
{
	m_nDay   = date.m_nDay;
	m_nMonth = date.m_nMonth;
	m_nYear  = date.m_nYear;
	// m_bDebug is not copied !

	return *this;
}


// virtual, see operator=
bool CDate::Copy(const CDate *date)
{
	// invalid class
	if (date == NULL || date == this)
		return false;

	// use non virtual reference based copy
	// return value isn't needed
	operator=(*date);

	// we're done
	return true;
}


// compare two dates
bool CDate::operator ==(const CDate &date) const
{
	// m_bDebug is not neccessary
	return (m_nDay   == date.m_nDay   &&
			m_nMonth == date.m_nMonth &&
			m_nYear  == date.m_nYear);
}


// virtual, see operator==
bool CDate::EqualValue(CDate *date) const
{
	// invalid class
	if (date == NULL)
		return false;

	// use non virtual reference based copy
	return operator==(*date);
}


// set attributes, returns validility of date
inline bool CDate::SetDay(int nDay)
{
	m_nDay = nDay;
	return IsValid();
}
inline bool CDate::SetMonth(int nMonth)
{
	m_nMonth = nMonth;
	return IsValid();
}
inline bool CDate::SetYear(int nYear)
{
	m_nYear = nYear;
	return IsValid();
}

// return attributes
inline int CDate::GetDay() const
{
	return m_nDay;
}
inline int CDate::GetMonth() const
{
	return m_nMonth;
}
inline int CDate::GetYear() const
{
	return m_nYear;
}