SocialPub/PrivaPub/Domain/Social/Notifications.cs

using MongoDB.Driver;
using MongoDB.Entities;

using PrivaPub.Models.Social;

namespace PrivaPub.Domain.Social
{
	public static class Notifications
	{
		// told of every notification once it is kept for the persona's lists and streams: never one the notification policy
		// filtered or dropped, nor one its blocks and mutes hid. Web Push hangs here (R9, WebPushDispatcher, set while the
		// host runs; the command line sets nothing). Whatever it does never fails the notification.
		public static Func<Notification, CancellationToken, Task> Told { get; set; }

		static async Task Tell(Notification notification, CancellationToken token)
		{
			if (Told is not { } told)
				return;
			try
			{
				await told(notification, token);
			}
			catch (Exception)
			{
				//the hook logs its own failures
			}
		}

		public static async Task Add(string avatarId, NotificationType type, string fromAccountId, string fromActorUri, string postId,
			CancellationToken token, string emoji = default, string emojiUrl = default, string text = default)
		{
			if (string.IsNullOrEmpty(avatarId) || avatarId == fromAccountId && type != NotificationType.Poll)
				return;
			if ((await Relationships.Hidden.AuthorsHiddenFrom(avatarId, new[] { fromActorUri }, forNotifications: true, token)).Count > 0)
				return;
			var action = await NotificationPolicies.Judge(avatarId, type, fromAccountId, fromActorUri, postId, token);
			if (action == NotificationAction.Drop)
				return;
			try
			{
				var notification = new Notification
				{
					AvatarId = avatarId,
					Type = type,
					FromAccountId = fromAccountId,
					FromActorURI = fromActorUri,
					PostId = postId,
					Emoji = emoji,
					EmojiURL = emojiUrl,
					Text = text,
					DedupeKey = emoji == default ? $"{type}|{avatarId}|{fromActorUri}|{postId}" : $"{type}|{avatarId}|{fromActorUri}|{postId}|{emoji}",
					Filtered = action == NotificationAction.Filter
				};
				await DB.Default.SaveAsync(notification, token);
				// filtered: in its account's request, told to no stream
				if (notification.Filtered)
				{
					await NotificationPolicies.Requested(notification, token);
					return;
				}
				var told = new Timelines.Streams.Event("notification", notification.ID);
				Timelines.Streams.ToPersona(avatarId, new Timelines.Streams.Key(Timelines.Streams.User), told);
				Timelines.Streams.ToPersona(avatarId, new Timelines.Streams.Key(Timelines.Streams.UserNotification), told);
				await Tell(notification, token);
			}
			catch (MongoWriteException ex) when (ex.WriteError?.Category == ServerErrorCategory.DuplicateKey)
			{
			}
		}

		// A warning from this server's staff (completion program R6): Mastodon's moderation_warning, from the persona itself as
		// Mastodon's are (an AccountWarning has no account behind it), never judged by the notification policy, one for each
		// act. A suspended persona reads it once its suspension is lifted; until then its login sees it suspended in its list
		// of personas (/clientapi/avatar/private/list).
		public static async Task Warn(string avatarId, string personaUri, string action, string text, IReadOnlyList<string> postIds, CancellationToken token)
		{
			if (string.IsNullOrEmpty(avatarId))
				return;
			var ids = postIds?.Where(id => !string.IsNullOrEmpty(id)).Distinct().ToList() ?? new List<string>();
			var notification = new Notification
			{
				AvatarId = avatarId,
				Type = NotificationType.ModerationWarning,
				FromAccountId = avatarId,
				FromActorURI = personaUri,
				PostId = ids.FirstOrDefault(),
				StatusIds = ids.Count > 1 ? ids : null,
				Text = string.IsNullOrWhiteSpace(text) ? default : text.Trim(),
				WarningAction = action,
				DedupeKey = $"{NotificationType.ModerationWarning}|{avatarId}|staff|{MongoDB.Bson.ObjectId.GenerateNewId()}"
			};
			await DB.Default.SaveAsync(notification, CancellationToken.None);//an act that was done is told even when its request went away
			var told = new Timelines.Streams.Event("notification", notification.ID);
			Timelines.Streams.ToPersona(avatarId, new Timelines.Streams.Key(Timelines.Streams.User), told);
			Timelines.Streams.ToPersona(avatarId, new Timelines.Streams.Key(Timelines.Streams.UserNotification), told);
			await Tell(notification, CancellationToken.None);
		}
	}
}