@inherits LocalizableComponentBase

@* The administrators' announcements shown now (/api/v1/announcements) that the persona has not dismissed, one at a time
   above the feed's tabs: their words (sanitized HTML from the administrator's Markdown), when they run, and the
   reactions personas left, which the persona adds and takes back with a unicode emoji. Dismissed, one is gone for this
   persona. New, changed and removed ones, and the reactions' counts, come through the user stream
   (StreamingService.HearAnnouncements); the banner renders itself and never touches the feed's cards. *@
@if (Current is { } current)
{
	<section class="flex-none flex flex-col gap-2 p-3 rounded-xl neo-raised neo-xs" aria-label="@Localizer["Announcements"]"
			 data-announcement-banner data-announcement="@current.Id">
		<div class="flex items-center gap-2 pointer-coarse:gap-2">
			<i class="ion-md-megaphone text-lg text-primary" aria-hidden="true"></i>
			<b class="text-sm">@Localizer["Announcement"]</b>
			<span class="text-xs opacity-70" title="@current.PublishedAt.ToLocalTime().ToString(SUtility.dateTimeFormatExt)">
				@current.PublishedAt.GetPassedTime(Localizer)
			</span>
			@if (ShownCount > 1)
			{
				<span class="inline-flex items-center gap-1 pointer-coarse:gap-2">
					<DButton Size="DSize.Xs" Variant="DButtonVariant.Ghost" Disabled="index == 0" OnClick="() => index--" aria-label="@Localizer["Previous announcement"]"
							 title="@Localizer["Previous announcement"]" data-announcement-previous>
						<i class="ion-md-arrow-back" aria-hidden="true"></i>
					</DButton>
					<span class="text-xs tabular-nums" data-announcement-position>@Localizer["{0} of {1}", index + 1, ShownCount]</span>
					<DButton Size="DSize.Xs" Variant="DButtonVariant.Ghost" Disabled="index >= ShownCount - 1" OnClick="() => index++" aria-label="@Localizer["Next announcement"]"
							 title="@Localizer["Next announcement"]" data-announcement-next>
						<i class="ion-md-arrow-forward" aria-hidden="true"></i>
					</DButton>
				</span>
			}
			<span class="flex-1"></span>
			<DButton Size="DSize.Xs" Variant="DButtonVariant.Ghost" Shape="DButtonShape.Circle" Disabled="IsDefaultDisabled || isActing" OnClick="Dismiss"
					 aria-label="@Localizer["Dismiss"]" title="@Localizer["Dismiss"]" data-announcement-dismiss>
				<i class="ion-md-close" aria-hidden="true"></i>
			</DButton>
		</div>
		@if (current.StartsAt is not null || current.EndsAt is not null)
		{
			<p class="text-xs opacity-70" data-announcement-when>@When(current)</p>
		}
		<div class="post-content doc-content text-sm break-words max-h-28 md:max-h-40 overflow-y-auto">@((MarkupString)current.Content)</div>
		<div class="flex flex-wrap items-center gap-1 pointer-coarse:gap-2" data-announcement-reactions>
			@foreach (var reaction in current.Reactions)
			{
				<DButton Size="DSize.Xs" Active="reaction.Me == true" Disabled="IsDefaultDisabled || isActing" OnClick="() => React(reaction.Name, reaction.Me != true)"
						 title="@reaction.Name" aria-pressed="@(reaction.Me == true ? "true" : "false")" data-announcement-reaction="@reaction.Name">
					@if (reaction.Url is { Length: > 0 } image)
					{
						<img alt="@reaction.Name" class="h-4 w-4 object-contain" src="@image" />
					}
					else
					{
						<span>@reaction.Name</span>
					}
					<span class="tabular-nums">@reaction.Count</span>
				</DButton>
			}
			<DDropdown @bind-IsOpen="isReactionsOpen" Placement="DDropdownPlacement.Bottom" CloseOnContentClick="true" SheetOnNarrow="true"
					   TriggerClass="@(isReactionsOpen ? "btn btn-xs btn-active" : "btn btn-xs")"
					   ContentClass="mt-2 flex gap-1 p-2 rounded-box max-md:grid max-md:grid-cols-4 max-md:gap-2" title="@Localizer["React"]" data-announcement-react>
				<Trigger><i aria-hidden="true" class="ion-md-happy"></i></Trigger>
				<ChildContent>
					@foreach (var emoji in QuickReactions)
					{
						<DButton Size="DSize.Sm" Disabled="@(IsDefaultDisabled || isActing)" OnClick="() => React(emoji, true)" data-announcement-react-emoji="@emoji">@emoji</DButton>
					}
				</ChildContent>
			</DDropdown>
		</div>
	</section>
}

@code {
	static readonly string[] QuickReactions = ["👍", "❤️", "😂", "🎉", "🔥", "😮", "😢"];

	[Inject] AnnouncementService AnnouncementService { get; set; }
	[Inject] StreamingService Streaming { get; set; }

	List<Announcement> announcements = [];
	int index;
	bool isActing;
	bool isReactionsOpen;
	string loadedPersonaId;

	// what the persona has not dismissed, oldest first as the server lists them
	List<Announcement> Shown => [.. announcements.Where(a => a.Read != true)];

	int ShownCount => announcements.Count(a => a.Read != true);

	// the one in view, or none
	Announcement Current => Shown is [_, ..] shown ? shown[Math.Clamp(index, 0, shown.Count - 1)] : null;

	protected override void OnInitialized() => Streaming.Announced += OnAnnounced;

	// another persona reads its own: its dismissals and reactions
	protected override async Task OnParametersSetAsync()
	{
		if (CascadingState.PersonaId is null || CascadingState.PersonaId == loadedPersonaId)
			return;
		loadedPersonaId = CascadingState.PersonaId;

		if (CascadingState.IsOffline)
		{
			WhenOnline(LoadData);
			StartOnlinePolling();
			IsLoading = false;
			return;
		}

		await LoadData();
		IsLoading = false;
	}

	async Task LoadData()
	{
		announcements = await AnnouncementService.List();
		index = 0;
		await Streaming.HearAnnouncements(true);
	}

	string When(Announcement announcement)
	{
		var format = announcement.AllDay ? SUtility.dateTimeFormat : SUtility.dateTimeFormatExt;
		var starts = announcement.StartsAt?.ToLocalTime().ToString(format);
		var ends = announcement.EndsAt?.ToLocalTime().ToString(format);
		return (starts, ends) switch
		{
			({ } from, { } to) => Localizer["From {0} to {1}", from, to],
			({ } from, null) => Localizer["From {0}", from],
			_ => Localizer["until {0}", ends]
		};
	}

	async Task Dismiss()
	{
		if (Current is not { } announcement)
			return;
		isActing = true;
		var result = await AnnouncementService.Dismiss(announcement.Id);
		isActing = false;
		if (result.IsInvalid)
		{
			Toast.AddResponseError(result);
			return;
		}

		announcement.Read = true;
		index = Math.Clamp(index, 0, Math.Max(0, ShownCount - 1));
	}

	// the counts are read again afterwards: the stream may have told of this very reaction already
	async Task React(string emoji, bool add)
	{
		if (Current is not { } announcement)
			return;
		isActing = true;
		var result = await AnnouncementService.React(announcement.Id, emoji, add);
		if (result.IsInvalid)
		{
			isActing = false;
			Toast.AddResponseError(result);
			return;
		}

		var position = index;
		announcements = await AnnouncementService.List();
		index = Math.Clamp(position, 0, Math.Max(0, ShownCount - 1));
		isActing = false;
	}

	Task OnAnnounced(AnnouncementMessage message) => InvokeAsync(() =>
	{
		switch (message.Event)
		{
			case "announcement" when message.Announcement is { } changed:
				var at = announcements.FindIndex(a => a.Id == changed.Id);
				if (at < 0)
					announcements.Add(changed);
				else
					announcements[at] = changed;
				break;
			case "announcement.delete" when message.DeletedId is { } id:
				announcements.RemoveAll(a => a.Id == id);
				break;
			case "announcement.reaction" when message.Reaction is { } reaction && announcements.Find(a => a.Id == reaction.AnnouncementId) is { } reacted:
				var known = reacted.Reactions.Find(r => r.Name == reaction.Name);
				reacted.Reactions = reaction.Count <= 0
					? [.. reacted.Reactions.Where(r => r.Name != reaction.Name)]
					: known is null
						? [.. reacted.Reactions, new AnnouncementReaction { Name = reaction.Name, Count = reaction.Count, Me = false }]
						: [.. reacted.Reactions.Select(r => r.Name == reaction.Name ? new AnnouncementReaction { Name = r.Name, Count = reaction.Count, Me = r.Me, Url = r.Url } : r)];
				break;
			default:
				return;
		}
		index = Math.Clamp(index, 0, Math.Max(0, ShownCount - 1));
		StateHasChanged();
	});

	public override async ValueTask DisposeAsync()
	{
		Streaming.Announced -= OnAnnounced;
		await Streaming.HearAnnouncements(false);
		await base.DisposeAsync();
	}
}