decePubClient/Components/Admin/RelaysPanel.razor

@inherits LocalizableComponentBase

@* The relays the server's actor subscribes to (/clientapi/admin/relays): the configuration's (Federation:Relays, removed
   only there) and the ones added here, each with its subscription's state. PrivaPub answers an addition or a removal at
   once (202) and subscribes or unsubscribes in the background, since reaching a relay takes a fetch, so the panel reads
   the list again a few seconds later. *@
<div class="flex flex-col gap-3 w-full" data-relays>
	<div class="flex flex-wrap items-center gap-2 pointer-coarse:gap-2">
		<DInput TValue="string" class="flex-1 min-w-48" Type="url" @bind-Value="address" Immediate="true" autocomplete="off" maxlength="2048"
				placeholder="@Localizer["https://relay.example/actor"]" aria-label="@Localizer["The relay's address"]" data-relay-address>
			<Prefix><i class="ion-md-radio" aria-hidden="true"></i></Prefix>
		</DInput>
		<DButton Size="DSize.Sm" Color="DColor.Primary" Disabled="IsDefaultDisabled || isSaving || string.IsNullOrWhiteSpace(address)" OnClick="Add" data-relay-add>
			<i class="ion-md-add" aria-hidden="true"></i><span>@Localizer["Add the relay"]</span>
		</DButton>
	</div>
	<p class="text-xs opacity-70">@Localizer["The https address of the relay's actor, or of its inbox. Public posts of this server go to it, and its posts come here."]</p>

	@if (IsLoading)
	{
		<p class="flex w-full items-center justify-center gap-2">
			<DLoading Variant="DLoadingVariant.Dots" LabelText="@Localizer["loading"]" />
			@Localizer["loading"]
		</p>
	}
	else if (relays.Count == 0)
	{
		<p class="text-sm opacity-70" data-relays-empty>@Localizer["The server subscribes to no relay."]</p>
	}

	@foreach (var relay in relays)
	{
		<div class="flex flex-col gap-1 p-2 rounded-lg neo-raised neo-2xs" data-relay="@relay.Address" data-relay-state="@relay.State"
			 data-relay-source="@relay.Source">
			<div class="flex flex-wrap items-center gap-2 pointer-coarse:gap-2">
				<b class="flex-1 min-w-0 break-all text-sm">@relay.Address</b>
				@switch (relay.State)
				{
					case "accepted":
						<DBadge Size="DSize.Sm" Variant="DBadgeVariant.Soft" Color="DColor.Success">@Localizer["Subscribed"]</DBadge>
						break;
					case "pending":
						<DBadge Size="DSize.Sm" Variant="DBadgeVariant.Soft" Color="DColor.Warning">@Localizer["Waiting for the relay"]</DBadge>
						break;
					case "rejected":
						<DBadge Size="DSize.Sm" Variant="DBadgeVariant.Soft" Color="DColor.Error">@Localizer["Refused by the relay"]</DBadge>
						break;
					default:
						<DBadge Size="DSize.Sm" Variant="DBadgeVariant.Soft">@Localizer["Not asked yet"]</DBadge>
						break;
				}
				@if (relay.Source == "configuration")
				{
					<DBadge Size="DSize.Sm" Variant="DBadgeVariant.Outline" title="@Localizer["Named by the configuration (Federation:Relays): removed only there."]">
						@Localizer["Configured"]
					</DBadge>
				}
				else
				{
					<DButton Size="DSize.Sm" Disabled="IsDefaultDisabled || isSaving" OnClick="() => Remove(relay)" data-relay-remove>
						<i class="ion-md-trash text-error" aria-hidden="true"></i><span>@Localizer["Remove"]</span>
					</DButton>
				}
			</div>
			@if (relay.ActorURI is { Length: > 0 } actor && actor != relay.Address)
			{
				<p class="text-xs opacity-70 break-all">@Localizer["Its actor: {0}", actor]</p>
			}
			<p class="text-xs opacity-70">
				@if (relay.RequestedAt is { } requested)
				{
					<span title="@requested.ToLocalTime().ToString(SUtility.dateTimeFormatExt)">@Localizer["Asked {0} ago", requested.GetPassedTime(Localizer)]</span>
				}
				@if (relay.AnsweredAt is { } answered)
				{
					<span title="@answered.ToLocalTime().ToString(SUtility.dateTimeFormatExt)"> · @Localizer["answered {0} ago", answered.GetPassedTime(Localizer)]</span>
				}
			</p>
			@if (relay.Source == "configuration")
			{
				<p class="text-xs opacity-70">@Localizer["Named by the configuration (Federation:Relays): removed only there."]</p>
			}
		</div>
	}
</div>

@code {
	// when the list is read again after a change: subscribing to a relay is a fetch, then its answer
	static readonly TimeSpan[] Rereads = [TimeSpan.FromSeconds(4), TimeSpan.FromSeconds(15)];

	[Inject] InstanceAdminService InstanceAdminService { get; set; }

	List<ViewRelay> relays = [];
	string address;
	bool isSaving;
	CancellationTokenSource rereading;

	protected override async Task OnInitializedAsync()
	{
		if (CascadingState.IsOffline)
		{
			WhenOnline(LoadData);
			StartOnlinePolling();
			IsLoading = false;
			return;
		}

		await LoadData();
		IsLoading = false;
	}

	async Task LoadData() => relays = await InstanceAdminService.Relays();

	async Task Add()
	{
		isSaving = true;
		var result = await InstanceAdminService.AddRelay(address);
		isSaving = false;
		if (result.IsInvalid)
		{
			Toast.AddResponseError(result);
			return;
		}

		relays = (List<ViewRelay>)result.Data;
		address = null;
		Toast.AddResponseSuccess(Localizer["The relay is added: the server subscribes to it now."]);
		await ReadAgainSoon();
	}

	async Task Remove(ViewRelay relay)
	{
		isSaving = true;
		var result = await InstanceAdminService.RemoveRelay(relay.Address);
		isSaving = false;
		if (result.IsInvalid)
		{
			Toast.AddResponseError(result);
			return;
		}

		relays = (List<ViewRelay>)result.Data;
		Toast.AddResponseSuccess(Localizer["The relay is removed: the server unsubscribes from it now."]);
		await ReadAgainSoon();
	}

	// the background subscription answers later: the list is read again, the last change's timer replacing the one before
	async Task ReadAgainSoon()
	{
		if (rereading is not null)
		{
			await rereading.CancelAsync();
			rereading.Dispose();
		}
		rereading = new();
		_ = ReadAgain(rereading.Token);
	}

	async Task ReadAgain(CancellationToken cancellationToken)
	{
		foreach (var pause in Rereads)
		{
			try
			{
				await Task.Delay(pause, cancellationToken);
			}
			catch (OperationCanceledException)
			{
				return;
			}
			var read = await InstanceAdminService.Relays(cancellationToken);
			if (cancellationToken.IsCancellationRequested)
				return;
			// an empty answer to a list that had relays is a failed read: a change here showed its own list at once
			if (read.Count == 0 && relays.Count > 0)
				continue;
			relays = read;
			await InvokeAsync(StateHasChanged);
		}
	}

	public override async ValueTask DisposeAsync()
	{
		if (rereading is not null)
		{
			await rereading.CancelAsync();
			rereading.Dispose();
		}
		await base.DisposeAsync();
	}
}