/// <summary>
/// Set the CurrentCulture of current thread to a new fixed Persian culture.
/// </summary>
/// <returns>The fixed Persian cultreinfo.</returns>
public static CultureInfo FixAndSetCurrentCulture()
{
    CultureInfo culture = FixPersianCulture(null,FixCultureOptions.foptAll);
    System.Threading.Thread.CurrentThread.CurrentCulture = culture;
    System.Threading.Thread.CurrentThread.CurrentUICulture = culture;
    return culture;
}

/// <summary>
/// Fixes CultureInfo for Persian resources (months and day names) and also PersianCalendar.
/// </summary>
/// <param name="culture">The CultureInfo instace to be fixed. If NULL, a new instance will be created and returned.</param>
/// <param name="options">Specifies what to be fixed.</param>
/// <returns>A new instance of fixed Persian CultureInfo.</returns>
public static CultureInfo FixPersianCulture(CultureInfo culture, FixCultureOptions options)
{
    PropertyInfo calendarID = typeof(Calendar).GetProperty("ID", BindingFlags.NonPublic | BindingFlags.Instance);
    FieldInfo cultureInfoReadOnly = typeof(CultureInfo).GetField("m_isReadOnly", BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance);
    FieldInfo cultureInfoCalendar = typeof(CultureInfo).GetField("calendar", BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance);
    //FieldInfo cultureInfoReadOnly = typeof(CultureInfo).GetField("m_", BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance);
    if (culture == null)
        culture = new CultureInfo("fa-IR", false);
    if (culture == null || culture.LCID != 1065)
        return culture;
    if ((options & FixCultureOptions.foptAll) == FixCultureOptions.foptAll)
        options = FixCultureOptions.foptCalendarInCulture | FixCultureOptions.foptCalendarInDateFormatInfo |
                FixCultureOptions.foptOptionalCalendars;
    if ((options & FixCultureOptions.foptOptionalCalendars) == FixCultureOptions.foptOptionalCalendars)
    {
        FixOptionalCalendars(culture, 4);
        culture = new CultureInfo("fa-IR", false);
    }
            
    bool readOnly = (bool)cultureInfoReadOnly.GetValue(culture);
    if (readOnly)
    {
        cultureInfoReadOnly.SetValue(culture, false);
    }
    if ((options & FixCultureOptions.foptCalendarInDateFormatInfo) == FixCultureOptions.foptCalendarInDateFormatInfo)
        culture.DateTimeFormat = FixPersianDateTimeFormat(culture.DateTimeFormat, true);
    else
        FixPersianDateTimeFormat(culture.DateTimeFormat, false);
    if ((options & FixCultureOptions.foptCalendarInCulture )
                                == FixCultureOptions.foptCalendarInCulture)
    {
        cultureInfoCalendar.SetValue(culture, new PersianCalendar());
    }
    if (readOnly)
    {
        cultureInfoReadOnly.SetValue(culture, true);
    }
    return culture;
}