Added Razor components for loadable remote content

1 files changed, 59 insertions, 0 deletions

diff --git a/Pages/Component/LoadableContent.razor b/Pages/Component/LoadableContent.razor
new file mode 100644
index 0000000..570317f
--- /dev/null
+++ b/Pages/Component/LoadableContent.razor
@@ -0,0 +1,59 @@
+@attribute [CascadingTypeParameter(nameof(T))]
+@typeparam T
+
+<CascadingValue Value=this>
+	@ChildContent
+</CascadingValue>
+
+@code {
+	[Parameter]
+	public RenderFragment? ChildContent { get; set; }
+
+	[Parameter]
+	public required Func<Task<T>> DataSource { private get; set; }
+
+	public T Data { get; private set; }
+
+	public ComponentState ComponentState { get; private set; } = ComponentState.Loading;
+
+	public event EventHandler? OnStateChanged;
+
+	private bool   reloadRequested = false;
+	private Task?  loadTask        = null;
+	private object loadLock        = new();
+
+	protected override void OnInitialized() => Load();
+
+	public void Load() {
+		lock(loadLock) {
+			reloadRequested = true;
+			if(loadTask is null || loadTask.IsCompleted) {
+				//loadTask = Task.Run(LoadInternalAsync);
+				loadTask = LoadInternalAsync();
+			}
+		}
+	}
+
+	private async Task LoadInternalAsync() {
+		while(true) {
+			lock(loadLock) {
+				if(!reloadRequested)
+					break;
+				reloadRequested = false;
+			}
+
+			//ComponentState = ComponentState.Loading;
+			//await InvokeAsync(() => OnStateChanged?.Invoke(this, EventArgs.Empty));
+			//await InvokeAsync(() => StateHasChanged());
+			try {
+				Data           = await DataSource.Invoke();
+				ComponentState = ComponentState.Loaded;
+			} catch {
+				ComponentState = ComponentState.Error;
+			}
+
+			await InvokeAsync(() => OnStateChanged?.Invoke(this, EventArgs.Empty));
+			await InvokeAsync(() => StateHasChanged());
+		}
+	}
+}