decePubClient/Services/FeedMemory.cs

using decePubClient.Models;
using decePubClient.Models.Mastodon;

using PrivaPub.ClientModels.Group;

namespace decePubClient.Services
{
	/// <summary>
	/// The feed as the reader left it: its query, posts, waiting posts, cursors and scroll. Coming back from a thread or a
	/// profile shows it again at once instead of reading it anew; newer posts come behind the "new" button as usual. Kept
	/// ten minutes, and only for the same feed of the same persona.
	/// </summary>
	public class FeedMemory
	{
		public static readonly TimeSpan Keep = TimeSpan.FromMinutes(10);

		public FeedQuery Query { get; private set; }
		public List<FeedPost> Posts { get; private set; } = [];
		public List<FeedPost> Pending { get; private set; } = [];
		public List<ViewGroup> Groups { get; private set; } = [];
		public List<MastodonList> Lists { get; private set; } = [];
		public string MinId { get; private set; }
		public string MaxId { get; private set; }
		public double ScrollTop { get; private set; }
		public DateTime SavedAt { get; private set; }

		public void Save(FeedQuery query, List<FeedPost> posts, List<FeedPost> pending, List<ViewGroup> groups, List<MastodonList> lists,
			string minId, string maxId, double scrollTop)
		{
			Query = query;
			Posts = posts;
			Pending = pending;
			Groups = groups;
			Lists = lists;
			MinId = minId;
			MaxId = maxId;
			ScrollTop = scrollTop;
			SavedAt = DateTime.UtcNow;
		}

		/// <summary>Whether what is kept is recent and belongs to this persona.</summary>
		public bool Holds(string personaId) => Query is not null && Query.PersonaId == personaId && DateTime.UtcNow - SavedAt < Keep;

		public void Forget()
		{
			Query = null;
			Posts = [];
			Pending = [];
		}
	}
}