Neighbourhood.omg.lol/Components/PicList.razor

@inject IJSRuntime JS
@inject State State

@implements IDisposable

@if (Editable) {
  <EditPicDialog @ref="Dialog" id="EditPicModal"></EditPicDialog>
}

@if (pics != null) foreach (Pic pic in pics) {
  <PicCard Pic="pic" Editable="Editable" Dialog="Dialog"></PicCard>
}

<LoadingCard id="pics-loading" icon="fa-solid fa-images"></LoadingCard>

@code {
  [Parameter]
  public Func<bool, Task<List<Pic>?>> PicsFunc { get; set; }
  [Parameter]
  public bool Editable { get; set; } = false;

  public EditPicDialog? Dialog { get; set; }

  private List<Pic>? pics;
  private int count { get; set; } = 0;
  private int pageSize { get; } = 10;

  // TODO: There is a noticable rendering delay between the pics loading and the page rendering
  protected override async Task OnInitializedAsync() {
    await base.OnInitializedAsync();
    State.PropertyChanged += StateChanged;
    State.CanRefresh = true;

    if (pics == null || pics.Count == 0) await LoadNext();
    await JS.InvokeVoidAsync("removeElementById", "pics-loading");
  }

  public async Task<bool> PullUp() {
    int countBefore = count;
    await LoadNext();
    return (count != countBefore);
  }

  public async Task LoadNext(bool forceRefresh = false) {
    if (pics == null) pics = new List<Pic>();
    if (forceRefresh) {
      count = 0;
      pics.Clear();
    }

    var allPics = await PicsFunc(forceRefresh);
    if(allPics != null && count < allPics.Count) {
      pics.AddRange(allPics.Skip(count).Take(pageSize));
      count = pics.Count;
    }
    await InvokeAsync(StateHasChanged);
  }

  private async void StateChanged(object? sender, PropertyChangedEventArgs e) {
    if (e.PropertyName == nameof(State.IsRefreshing) && State.IsRefreshing) {
      await LoadNext(true);
      State.IsRefreshing = false;
    }

    if (e.PropertyName == nameof(State.AtBottom) && State.AtBottom) {
      await LoadNext();
    }
  }

  public void Dispose() {
    State.PropertyChanged -= StateChanged;
    State.CanRefresh = false;
  }
}