#include <iostream>
#include <string>
#include <vector>
using namespace std;

/* Prototype all the happy lil functions we get to use, woo! */
void menuPrint();
bool dateInvalid(int year=1900, int month=1, int day=1);
void playLeapYear();
bool leapYear(int year);
void playZodiac();
string zodiac(int year);
void playDayOfWeek();
int julian(int year, int month, int day);
string dayOfWeek(int year, int month, int day);
void playSols();
vector<int> sols(int year, int month, int day);

int main()
{
  string menuChoice;
  
  while (true)
    {
      menuPrint();
      cin >> menuChoice;

      if ((menuChoice == "q") || (menuChoice == "-1"))
	{
	  break;
	}
      else if (menuChoice == "1")
	{
	  playLeapYear();
	}
      else if (menuChoice == "2")
	{
	  playZodiac();
	}
      else if (menuChoice == "3")
	{
	  playDayOfWeek();
	}
      else
	{
	  cout << "FIXME" << endl;
	}
    }
  return 0;
}


void menuPrint()
{
  /* For printing the program menu */
  cout << "\nMain Menu — Enter an item's menu-number or input q or -1 to "
  "exit the program \n" 
  " 1) Leap years \n"
  " 2) Zodiac \n"
  " 3) Day of the week \n"
  " 4) Martian Calendar \n"
  " 5) Square (by value) \n"
  " 6) Square (reference) \n"
  " 7) Square (by pointer) \n" << endl;
}


void playLeapYear()
{
  /* The "leap year" game */
  int year = 0;
  cout << "Leap year:" << endl;
  while (dateInvalid(year))
    {
    cout << "Please enter a year 1900 or later:" << endl;
    cin.clear(); cin.ignore(10000, '\n');
    cin >> year;
    }
  cout << year << " is" << (leapYear(year) ? "" : " not") << " a leap year.";
  cout << endl;
}


bool leapYear(int year)
{
  /* Returns true if a year is a leap year, returns false otherwise */
  if (year % 4 != 0)
    { // Years that aren't divisible by 4 arent' leap years.
      return false;
    } // All years past here are divisible by 4
  else if (year % 100 != 0)
    { // 4th years which aren't divisble by 100 are always leap
      return true;
    } // All years past here are divisble by 4 and 100.
  else if (year % 400 != 0)
    { // Years divisible by 4 and 100 but not by 400 aren't leap years
      return false;
    } 
  else
    { // All years divisible by 4, 100, and 400 are leap years. 
      return true;
    }
}


bool dateInvalid(int year, int month, int day)
{
  /* Returns true if the given date is invalid. Defaults to valid date. */
  bool yearInvalid = (year < 1900);
  bool monthInvalid = (month < 1 || month > 12);
  int monthMax;
  switch(month)
    {
    case 2:
      monthMax = (leapYear(year) ? 29 : 28);
      break;
    case 4:
    case 6:
    case 9:
    case 11:
      monthMax = 30;
      break;
    default:
      monthMax = 31;
      break;
    }
  bool dayInvalid = ((day < 1) || (day > monthMax));
  return (yearInvalid || monthInvalid || dayInvalid);
}


void playZodiac()
{
  /* The "zodiac game" */
  int year = 0;
  cout << "Zodiac:" << endl;
  while(dateInvalid(year))
    {
      cout << "Please enter a year 1900 or later" << endl;
      cin.clear(); cin.ignore(10000, '\n');
      cin >> year;
    }
  cout << year << " is the year of the " << zodiac(year) << ". " << endl;
}


string zodiac(int year)
{
  /* Return a string representing the zodiac animal for year. Function reduces
     years to a 12-year cycle starting at 1900, the year of the rat. */
  switch((year - 1900) % 12)
    {
    case 0:   return "rat";
    case 1:   return "ox";
    case 2:   return "tiger";
    case 3:   return "rabbit";
    case 4:   return "dragon";
    case 5:   return "snake";
    case 6:   return "horse";
    case 7:   return "goat";
    case 8:   return "monkey";
    case 9:   return "rooster";
    case 10:  return "dog";
    case 11:  return "pig";
    default:  return "unknown";
    }
}


void playDayOfWeek()
{
  /* The "Day of the Week" game */
  int year = 0;
  int month = 0;
  int day = 0;
  cout << "Day of the Week:" << endl;
  while (dateInvalid(year, month, day))
    {
      cout << "Please enter a date 01-01-1900 or later. Use MM DD YYYY format.";
      cout << endl;
      cout << "Month:" << endl;
      cin.clear(); cin.ignore(10000, '\n');
      cin >> month;
      cout << "Day:" << endl;
      cin.clear(); cin.ignore(10000, '\n');
      cin >> day;
      cout << "Year:" << endl;
      cin.clear(); cin.ignore(10000, '\n');
      cin >> year;
    }
  cout << month << "-" << day << "-" << year << " falls on a ";
  cout << dayOfWeek(year, month, day) << endl;
}


int julian(int year, int month, int day)
{
  /* Where 1900-01-01 is 1, 1900-01-02 is 2, and so on */
  int julianDate = 0;
  // lDays is used for leap years, cDays is used for common years.
  // These vectors represent the sum of the days in all previous months.
  vector<int> lDays = {0,31,60,91,121,152,182,213,244,274,305,335,366};
  vector<int> cDays = {0,31,59,90,120,151,181,212,243,273,304,334,365};
  // yDays is equal to cDays on a common year or lDays on a leap year.
  vector<int> yDays = leapYear(year) ? lDays : cDays;
  for(int i = 1900; i < year; i++)
    {
      julianDate += leapYear(i) ? 366 : 365;
    }
  julianDate += yDays.at(month-1);
  julianDate += day;
  return julianDate;
}


string dayOfWeek(int year, int month, int day)
{
  /* Returns the day of the week of a given date as a string */
  
  /* We Subtract 1 from our julian date so that 1900-01-01 is 0. There
     is no real reason to do this other than that Monday is CLEARLY
     the start of the week and deserves to be 0, not 1. */
  int julianDate = julian(year, month, day) - 1; 
  julianDate %= 7;
  switch(julianDate)
    {
    case 0:  return "monday";
    case 1:  return "tuesday";
    case 2:  return "wednesday";
    case 3:  return "thursday";
    case 4:  return "friday";
    case 5:  return "saturday";
    case 6:  return "sunday";
    default: return "unknown";
    }
}


void playSols()
{
  int year = 0;
  int month = 0;
  int day = 0;
  cout << "Martian Calendar:" << endl;
    while (dateInvalid(year, month, day))
    {
      cout << "Please enter a date 01-01-1900 or later. Use MM DD YYYY format.";
      cout << endl;
      cout << "Month:" << endl;
      cin.clear(); cin.ignore(10000, '\n');
      cin >> month;
      cout << "Day:" << endl;
      cin.clear(); cin.ignore(10000, '\n');
      cin >> day;
      cout << "Year:" << endl;
      cin.clear(); cin.ignore(10000, '\n');
      cin >> year;
    }
  cout << "FIXME";
}


vector<int> sols(int year, int month, int day)
{
  int marsJulian = julian(year, month, day) / 1.027;
  int marsYear = marsJulian / 672;
  int marsMonth = (marsJulian - marsYear * 672) / 56;
  int marsDay = (marsJulian - marsYear * 672 - marsMonth * 56);