#include <stdexcept>
#include <iostream>
#include <iomanip>
#include <array>

#include "date.h"

using namespace std;
  
Date::Date(int y, int m, int d) : year(y), month(m), day(d)
{
  if ( month < 1 || month > 12 )
  {
    throw std::domain_error{"Month " + to_string(m) + " doesn't exist!"};
  }
  if (  day < 1 || day > days_in_month() )
  {
    throw std::domain_error{"Day " + to_string(day) + " invalid"};
  }
}

bool Date::is_leap_year() const
{
  if ( year % 400 == 0 )
    return true;
  if ( year % 100 == 0 )
    return false;
  return year % 4 == 0;
}

int Date::days_in_month() const
{
  static constexpr const array<int, 13> days
  {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
  
  if (month < 1 || month > 12)
    return 0;
  
  if ( month == 2 && is_leap_year() )
    return 29;
  
  return days.at(month);
}

void Date::next_date()
{
  ++day;
  if ( day > days_in_month() )
  {
    day = 1;
    ++month;
    
    if (month > 12)
    {
      month = 1;
      ++year;
    }
  }
}

ostream& operator<<(ostream & os, Date const& d)
{
  return os << setfill('0')
            << setw(4) << d.year << "-"
            << setw(2) << d.month << "-"
            << setw(2) << d.day
            << setfill(' ');
}