#include <iostream>
#include <ctime>
#include <cstdio>
#include <sstream>
#include <stdexcept>
#include <limits>

using namespace std;

#define JAN "January"
#define FEB "February"
#define MAR "March"
#define APR "April"
#define MAY "May"
#define JUN "June"
#define JUL "July"
#define AUG "August"
#define SEP "September"
#define OCT "October"
#define NOV "November"
#define DEC "December"

#define SUN "Sun"
#define MON "Mon"
#define TUE "Tue"
#define WED "Wed"
#define THU "Thu"
#define FRI "Fri"
#define SAT "Sat"

enum Month
{
    Jan = 1,
    Feb,
    Mar,
    Apr,
    May,
    Jun,
    Jul,
    Aug,
    Sep,
    Oct,
    Nov,
    Dec
};

enum Day
{
    Sun = 0,
    Mon,
    Tue,
    Wed,
    Thu,
    Fri,
    Sat
};

class Date
{
public:
    class Invalid : public runtime_error
    {
    public:
        Invalid() : runtime_error("Invalid date") {}
    };

    Date() : y(2001), m(Jan), d(1), days_in_month(31) {}
    Date(int yy, Month mm, int dd) : y(yy), m(mm), d(dd)
    {
        if (!is_valid(yy, mm, dd))
        {
            throw Invalid();
        }
    }

    int day() const { return d; }
    Month month() const { return m; }
    int year() const { return y; }
    int days() const { return days_in_month; }

    void add_day();
    void add_month();
    void add_year(int n);

private:
    int y;
    Month m;
    int d;
    int days_in_month;

    bool is_valid(int y, Month m, int d);
    bool leapyear(int y)
    {
        return (y % 4 == 0 && y % 100 != 0) || y % 400 == 0;
    }
};

bool Date::is_valid(int y, Month m, int d)
{
    if (y < 1583)
        return false; // gregorian start
    if (d < 0)
        return false;
    if (m < Jan || Dec < m)
        return false;

    days_in_month = 31;

    switch (m)
    {
    case Feb:
        days_in_month = (leapyear(y)) ? 29 : 28;
        break;
    case Apr:
    case Jun:
    case Sep:
    case Nov:
        days_in_month = 30;
        break;
    }

    if (days_in_month < d)
        return false;

    return true;
}

void Date::add_day()
{
    d++;

    if (d > days_in_month)
    {
        d = 1;
        add_month();
    }
}

void Date::add_month()
{
    if (m == Dec)
    {
        m = Jan;
        add_year(1);
    }
    else if (m == Jan && d == 29 && !leapyear(y))
    {
        m = (Month)((int)m + 1);
        d = 28;
    }
    else
    {
        m = (Month)((int)m + 1);
    }

    if (!is_valid(y, m, d))
    {
        throw Invalid();
    }
}

void Date::add_year(int n)
{
    if (m == Feb && d == 29 && !leapyear(y + n))
    {
        m = Mar;
        d = 1;
    }
    y += n;
}

tm makeTM(Date date)
{
    tm get_tm = {};
    int d = date.day();
    int m = (int)date.month();
    int y = date.year();

    get_tm.tm_year = y - 1900;
    get_tm.tm_mon = m - 1;
    get_tm.tm_mday = d;

    if (mktime(&get_tm) == -1) {
        cerr << "Error: Invalid date" << endl;
        exit(1);
    }

    return get_tm;
}

static int stoi(string &s)
{
    int i;
    istringstream(s) >> i;
    if (istringstream(s).fail()) {
        cerr << "Error: Invalid string to int conversion" << endl;
        exit(1);
    }
    return i;
}

int getDayOfWeek(const Date date)
{
    tm get_day = makeTM(date);
    return get_day.tm_wday;
}

string printMonth(Date &d)
{
    switch (d.month())
    {
    case Jan: return JAN;
    case Feb: return FEB;
    case Mar: return MAR;
    case Apr: return APR;
    case May: return MAY;
    case Jun: return JUN;
    case Jul: return JUL;
    case Aug: return AUG;
    case Sep: return SEP;
    case Oct: return OCT;
    case Nov: return NOV;
    case Dec: return DEC;
    default: return "mmm";
    }
}

void printHeader(const Date date)
{
    cout << "==========" << endl;
    tm title = makeTM(date);
    cout << asctime(&title);
    cout << "==========" << endl;

    printf("|");
    printf("%-3s|", SUN);
    printf("%-3s|", MON);
    printf("%-3s|", TUE);
    printf("%-3s|", WED);
    printf("%-3s|", THU);
    printf("%-3s|", FRI);
    printf("%-3s|", SAT);
    printf("\n\n");
}

void printWeek(Date date)
{
    Date begin(date.year(), date.month(), 1);
    int first_day = getDayOfWeek(begin);
    Day day = (Day)((int)first_day);

    printf("|");

    for (int i = 0; i < first_day; ++i)
    {
        printf("%-3s|", "X");
    }

    for (int i = 0; i < date.days(); ++i)
    {
        if (i + 1 == date.day())
        {
            printf("%-3s|", "_");
        }
        else
        {
            printf("%-3i|", begin.day());
        }

        switch (day)
        {
        case Sun: day = Mon; break;
        case Mon: day = Tue; break;
        case Tue: day = Wed; break;
        case Wed: day = Thu; break;
        case Thu: day = Fri; break;
        case Fri: day = Sat; break;
        case Sat:
            day = Sun;
            printf("\n|");
            break;
        }

        begin.add_day();
    }

    Date finish(date.year(), date.month(), date.days());
    int zero_sunday = 6;
    int end = zero_sunday - getDayOfWeek(finish);

    for (int i = 0; i < end; ++i)
    {
        printf("%-3s|", "X");
    }
}

int getValidInput(const string &prompt, int min, int max)
{
    int value;
    int attempts = 0;
    while (attempts < 3)
    {
        cout << prompt;
        string input;
        getline(cin, input);

        if (input.empty())
        {
            cout << "Input cannot be empty. Please try again." << endl;
            attempts++;
            continue;
        }

        istringstream iss(input);
        if (!(iss >> value) || value < min || value > max)
        {
            cout << "Invalid input. Please try again." << endl;
            attempts++;
        }
        else
        {
            return value;
        }
    }

    cout << "You have entered invalid numbers consecutively three times. The application will now close after pressing Enter." << endl;
    cin.get(); // Wait for the user to press Enter
    exit(1);
}

int main()
{
    int year = getValidInput("Enter the year (1583-9999): ", 1583, 9999);
    int month = getValidInput("Enter the month (1-12): ", 1, 12);
    int day = getValidInput("Enter the day (1-31): ", 1, 31);

    try {
        Date date(year, (Month)month, day);
        printHeader(date);
        printWeek(date);
    } catch (const Date::Invalid &e) {
        cerr << "Error: " << e.what() << endl;
        return 1;
    } catch (const exception &e) {
        cerr << "Error: " << e.what() << endl;
        return 1;
    }

    cout << "\n\nPress Enter to continue...";
    cin.get(); // Wait for the user to press Enter

    return 0;
}