ant-design-blazor/components/date-picker/internal/DatePickerDatetimePanel.razor

@namespace AntDesign.Internal
@typeparam TValue
@inherits DatePickerPanelBase<TValue>

@{
    var calendar = CultureInfo.Calendar;

    DateTime monthFirstDayDate = new DateTime(PickerValue.Year, PickerValue.Month, 1, 0, 0, 0);
    int monthFirstDayOfWeek = (int)calendar.GetDayOfWeek(monthFirstDayDate);

    // sunday should be 7
    if (monthFirstDayOfWeek == 0)
    {
        monthFirstDayOfWeek = DayOfWeekHelper.GetDiffForDayOfWeek(Locale.FirstDayOfWeek);
        Console.WriteLine($"{DateTime.Now} DatePickerDatePanel.razor monthFirstDayOfWeek: {monthFirstDayOfWeek}");
    }

    int diffDay = (int)Locale.FirstDayOfWeek - monthFirstDayOfWeek;
    DateTime startDate = monthFirstDayDate.AddDays(diffDay);

}

<div class='@($"{PrefixCls}-datetime-panel")' @ref="Ref">
    @if (IsShowTime)
    {
        <DatePickerTemplate TValue="TValue"
                            @attributes="GetAttritubes()"
                            MaxRow="6"
                            MaxCol="7"
                            ViewStartDate="startDate"
                            ShowFooter="@ShowToday"
                            IsInView="date => DateHelper.IsSameMonth(date, PickerValue)"
                            IsToday="date => DateHelper.IsSameDay(date, DatePicker.CurrentDate)"
                            IsSelected="date => DateHelper.IsSameDay(date, Value)"
                            GetColTitle='date => date.ToString(Locale.Lang.DateFormat, CultureInfo)'
                            OnValueSelect="OnSelectDate"
                            GetNextColValue="date => DateHelper.AddDaysSafely(date, 1)">
            <RenderPickerHeader>
                <DatePickerHeader TValue="TValue"
                                  @attributes="GetAttritubes()" />
            </RenderPickerHeader>
            <RenderTableHeader>
                <tr>
                    @foreach(string weekDay in Locale.Lang.ShortWeekDays)
                    {
                        <th>@weekDay</th>
                    }
                </tr>
            </RenderTableHeader>
            <RenderColValue Context="currentColDate">
                @currentColDate.Day
            </RenderColValue>
        </DatePickerTemplate>
    }

    @{
        var startTime = new DateTime(2020, 1, 1, 0, 0, 0);
        var timeFormat = ShowTimeFormat;

        if (Picker == DatePickerType.Time && !string.IsNullOrEmpty(Format))
        {
            timeFormat = Format;
        }

        DatePickerDisabledTime disabledTime = GetDisabledTime();
		bool isValueNull = Value is null;
		Func<int, int?, string> selected;
		string localValue;
		if (Value is null)
		{
			localValue = "";
			selected = (_, _) => "";
		}
		else
		{
			localValue = Value.Value.ToString(timeFormat);
			selected = (viewTime, valueTime) =>  viewTime == valueTime ? $"{PrefixCls}-time-panel-cell-selected" : "";
		}		
    }
    <div class="@(PrefixCls)-time-panel">
        @if(Picker == DatePickerType.Date)
        {
            <div class="@(PrefixCls)-header">
                <div class="@(PrefixCls)-header-view">
                    @localValue <br />
                </div>
            </div>
        }

        <div class="@(PrefixCls)-content">
            @if (timeFormat.ToLower().Contains("hh"))
            {
                <ul class="@(PrefixCls)-time-panel-column" style="position: relative;">
                    @for (int hour = 0; hour < 24; hour++)
                    {
                        var viewTime = startTime;
                        bool disabled = disabledTime._disabledHours.Contains(hour);
                        string isSelectedCls = selected(viewTime.Hour, Value?.Hour);
                        string disabledCls = disabled ? $"{PrefixCls}-time-panel-cell-disabled" : "";

                        <li class="@(PrefixCls)-time-panel-cell @isSelectedCls @disabledCls">
                            <div class="@(PrefixCls)-time-panel-cell-inner"
                                 @onclick="e => { if (!disabled) OnSelectHour(viewTime); }">
                                @hour
                            </div>
                        </li>

                        startTime = startTime.AddHours(1);
                    }
                </ul>
            }
            @if (timeFormat.ToLower().Contains("mm"))
            {
                <ul class="@(PrefixCls)-time-panel-column" style="position: relative;">
                    @for (int minute = 0; minute < 60; minute++)
                    {
                        var viewTime = startTime;
                        bool disabled = disabledTime._disabledMinutes.Contains(minute);
                        string isSelectedCls = selected(viewTime.Minute, Value?.Minute);
                        string disabledCls = disabled ? $"{PrefixCls}-time-panel-cell-disabled" : "";

                        <li class="@(PrefixCls)-time-panel-cell @isSelectedCls @disabledCls">
                            <div class="@(PrefixCls)-time-panel-cell-inner"
                                 @onclick="e => { if (!disabled) OnSelectMinute(viewTime); }">
                                @minute
                            </div>
                        </li>

                        startTime = startTime.AddMinutes(1);
                    }
                </ul>
            }
            @if (timeFormat.ToLower().Contains("ss"))
            {
                <ul class="@(PrefixCls)-time-panel-column" style="position: relative;">
                    @for (int second = 0; second < 60; second++)
                    {
                        var viewTime = startTime;
                        bool disabled = disabledTime._disabledSeconds.Contains(second);
						string isSelectedCls = selected(viewTime.Second, Value?.Second);
                        string disabledCls = disabled ? $"{PrefixCls}-time-panel-cell-disabled" : "";

                        <li class="@(PrefixCls)-time-panel-cell @isSelectedCls @disabledCls">
                            <div class="@(PrefixCls)-time-panel-cell-inner"
                                 @onclick="e => { if (!disabled) OnSelectSecond(viewTime); }">
                                @second
                            </div>
                        </li>

                        startTime = startTime.AddSeconds(1);
                    }
                </ul>
            }
        </div>
    </div>
</div>

@if (RenderExtraFooter != null)
{
    <div class="@(PrefixCls)-footer">
        <div class="@(PrefixCls)-footer-extra">
            @RenderExtraFooter
        </div>
    </div>
}

<div class="@(PrefixCls)-footer">
    <ul class="@(PrefixCls)-ranges">
        <li class="@(PrefixCls)-now">
            <a class="@(PrefixCls)-now-btn"
               @onclick="e => { OnSelectTime(DateTime.Now); Close(); }">
                @Locale.Lang.Now
            </a>
        </li>
        <li class="@(PrefixCls)-ok">
            <Button Type="@ButtonType.Primary"
                       OnClick="e => DatePicker.Close()">
                @Locale.Lang.Ok
            </Button>
        </li>
    </ul>
</div>