Display Calendars

main.cpp

#include <string>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <vector>
#include <time.h>

/// Display a base calendar
class cCalendar
{
protected:
    std::time_t myTime;
    int myMonthCount;

    void displayDay();
    void displayMonthHead(const struct tm &day);

    /// @brief Display day of month
    /// @param day
    ///
    /// Overwrite in specialised calendar class with an additional character

    virtual void decorateDay(const struct tm &day);

public:
    /// @brief CTOR, specifying start day
    /// @param year
    /// @param month
    /// @param day

    cCalendar(
        int year,
        int month, // 0 - 11
        int day);  // 1 - 31

    /// @brief Display the calendar
    /// @param monthCount number of months to display

    void display(int monthCount);
};

/** @brief Specialized calendar class to show 'w' on working days

There are three different shift patterns for a week: A, B, and C.
The shift pattern changes each week, starting on Monday, cycling through A,B,C and repeating
A has Fri & Sat off
B has Thus & Sun off
C has Tues & Wed off

*/
class cShiftCalendar : public cCalendar
{
public:
    cShiftCalendar(
        int year,
        int month, // 0 - 11
        int day)   // 1 - 31
        : cCalendar(year, month, day)
    {
    }
    void decorateDay(const struct tm &day);
};

cCalendar::cCalendar(
    int year,
    int month, // 0 - 11
    int day)   // 1 - 31
{
    struct tm tmDay = {0};
    tmDay.tm_year = year - 1900;
    tmDay.tm_mon = month;
    tmDay.tm_mday = day;
    tmDay.tm_hour = 12; // set to noon to avoid daylight saving time issues
    myTime = mktime(&tmDay);
}

void cCalendar::display(int monthCount)
{
    myMonthCount = monthCount + 1;
    while (myMonthCount)
    {
        displayDay();
        myTime += 24 * 60 * 60;
    }
}

void cCalendar::displayDay()
{
    struct tm day = *localtime(&myTime);

    if (day.tm_mday == 1)
    {
        // first day of a new month
        myMonthCount--;
        if (!myMonthCount)
            return;
        displayMonthHead(day);
    }
    std::string sday = std::to_string(day.tm_mday);
    if (sday.length() == 1)
        std::cout << " ";
    std::cout << sday;
    decorateDay(day);
    if (day.tm_wday == 0)
        std::cout << "\n";
}
void cCalendar::displayMonthHead(const struct tm &day)
{
    const std::string smonth[12]{"Jan", "Feb", "Mar"};
    std::cout << "\n\n"
              << smonth[day.tm_mon] << "\n Mo  Tu  We  Th  Fr  Sa  Su\n";
    int empty = day.tm_wday - 1;
    if (empty == -1)
        empty = 6;
    for (int k = 0; k < 4 * empty; k++)
        std::cout << " ";
}

void cCalendar::decorateDay(const struct tm &day)
{
    std::cout << "  ";
}

void cShiftCalendar::decorateDay(const struct tm &day)
{
    static int cycle = 0;

    if (day.tm_wday == 1)
    {
        // monday cycle change
        cycle++;
        if (cycle > 3)
            cycle = 1;
    }

    bool work = true;

    switch (cycle)
    {
    case 1:
        // off fri & Sat
        if (day.tm_wday == 5 ||
            day.tm_wday == 6)
            work = false;
        break;
    case 2:
        // off thu & sun
        if (day.tm_wday == 0 ||
            day.tm_wday == 4)
            work = false;
        break;
    case 3:
        // off tues and wed
        if (day.tm_wday == 2 ||
            day.tm_wday == 3)
            work = false;
        break;
    }
    if (work)
        std::cout << "w ";
    else
        std::cout << "  ";
}

main()
{
    cShiftCalendar calendar(2024, 0, 1);
    calendar.display(3);

    return 0;
}