canvasManagement/Management.Web/Shared/Semester/MonthDetail.razor

@using System.Linq
@using Management.Web.Shared.Semester.Day

@inject CoursePlanner planner

@code
{
  [Parameter, EditorRequired]
  public CalendarMonth Month { get; set; } = default!;

  public DayOfWeek[] WeekDaysList { get => (DayOfWeek[])Enum.GetValues(typeof(DayOfWeek)); }

  public string MonthName { get => Month?.DaysByWeek.First().FirstOrDefault(d => d != null)?.ToString("MMMM") ?? ""; }
  private string htmlLabel => "collapse"+MonthName;
  private bool isInPast =>
    new DateTime(Month.Year, Month.Month, 1) < new DateTime(DateTime.Now.Year, DateTime.Now.Month, 1);
  private string collapseClass => " collapse " + (isInPast ? "hide" : "show");
}

<h3 class="text-center">
  <a 
    role="button"
    data-bs-toggle="collapse" 
    data-bs-target="@("#" + htmlLabel)"
    aria-expanded="@( isInPast ? "false" : "true")" 
    aria-controls="@htmlLabel"
  >
    @MonthName
  </a>
</h3>

<div class="@collapseClass" id="@htmlLabel">
  <div class="row text-center fw-bold">
    @foreach (DayOfWeek day in WeekDaysList)
    {
      <div class="@(
          planner.LocalCourse?.Settings.DaysOfWeek.Contains(day) ?? false 
            ? "col" 
            : "col text-secondary"
        )">
        @day
      </div>
    }
  </div>

  @foreach (var week in Month.DaysByWeek)
  {
    <div class="row m-3">
    @foreach (var day in week)
      {
        <Day date="day"></Day>
      }
    </div>
  }
</div>