using MongoDB.Entities;

namespace PrivaPub.Infrastructure.Backup
{
	// What a restore did (or why it was abandoned), kept for the administrator's page and for the followers' grace: for
	// FollowersGrace after a restore the followers' digests (FEP-8fcf) are neither sent nor acted on to undo a follow, since
	// what the restore lost of either side is not the other's fault.
	public class RestoreRecord : Entity
	{
		public static readonly TimeSpan FollowersGrace = TimeSpan.FromDays(14);

		public string Backup { get; set; }
		public DateTime BackupCreatedAt { get; set; }
		public string PreRestore { get; set; }
		public string RequestedBy { get; set; }
		public DateTime RequestedAt { get; set; }
		public DateTime RestoredAt { get; set; } = DateTime.UtcNow;
		public int Attempts { get; set; }
		public bool Abandoned { get; set; }//nothing was changed: the server booted as it was
		public string Error { get; set; }
		public RestoreReport Report { get; set; } = new();

		static (DateTime Until, DateTime Read) _grace;

		/// <summary>Whether a restore ended less than FollowersGrace ago (read at most once a minute).</summary>
		public static async Task<bool> InFollowersGrace(CancellationToken token)
		{
			var now = DateTime.UtcNow;
			var cached = _grace;
			if (now - cached.Read > TimeSpan.FromMinutes(1))
			{
				var last = await DB.Default.Find<RestoreRecord>().Match(r => !r.Abandoned).Sort(r => r.RestoredAt, Order.Descending).ExecuteFirstAsync(token);
				cached = (last == default ? DateTime.MinValue : last.RestoredAt + FollowersGrace, now);
				_grace = cached;
			}
			return now < cached.Until;
		}

		/// <summary>Forgets what was read, so a restore made in this process counts at once.</summary>
		public static void Forget() => _grace = default;
	}

	public class RestoreReport
	{
		public int Collections { get; set; }
		public long Documents { get; set; }
		public int CollectionsDropped { get; set; }//live collections the backup had no documents in
		public int MediaRestored { get; set; }//files the live directory lacked, brought back
		public int MediaMissing { get; set; }
		public int RootsDeleted { get; set; }//deleted since the backup, deleted again
		public int PersonasDeleted { get; set; }
		public int GroupsDeleted { get; set; }
		public int PostsDeleted { get; set; }
		public List<string> RootsTombstoned { get; set; } = [];//made after the backup: deleted, their names kept
		public List<string> PersonasTombstoned { get; set; } = [];
		public List<string> GroupsTombstoned { get; set; } = [];
		public int PostsGone { get; set; }//local posts made after the backup: 410 from now on
		public int MediaTrashed { get; set; }
		public int ProtectiveKept { get; set; }//blocks, mutes, domain blocks, reserved names, reports, filters, deletions kept from since
		public int SessionsEnded { get; set; }
	}
}