TelegramBotFramework/TelegramBotBase/Tools/Time.cs

using System;

namespace TelegramBotBase.Tools;

public static class Time
{
    public static bool TryParseDay(string src, DateTime currentDate, out int resultDay)
    {
        return int.TryParse(src, out resultDay) && resultDay >= 1 &&
               resultDay <= DateTime.DaysInMonth(currentDate.Year, currentDate.Month);
    }

    public static bool TryParseMonth(string src, out int resultMonth)
    {
        return int.TryParse(src, out resultMonth) && resultMonth >= 1 && resultMonth <= 12;
    }

    public static bool TryParseYear(string src, out int resultYear)
    {
        return int.TryParse(src, out resultYear) && resultYear >= 0 && resultYear <= DateTime.MaxValue.Year;
    }

    public static DateTime StartOfWeek(this DateTime dt, DayOfWeek startOfWeek)
    {
        var diff = dt.DayOfWeek - startOfWeek;
        if (diff < 0)
        {
            diff += 7;
        }

        return dt.AddDays(-1 * diff).Date;
    }

    public static DateTime EndOfWeek(this DateTime dt, DayOfWeek startOfWeek)
    {
        return StartOfWeek(dt, startOfWeek).AddDays(6);
    }

    public static DateTime FirstDayOfMonth(this DateTime date)
    {
        return new DateTime(date.Year, date.Month, 1);
    }

    public static DateTime LastDayOfMonth(this DateTime date)
    {
        return FirstDayOfMonth(date).AddMonths(1).AddDays(-1);
    }
}