SocialPub/PrivaPub/Models/Group/DmGroup.cs

using MongoDB.Entities;

using System.Security.Cryptography;
using System.Text;

namespace PrivaPub.Models.Group
{
	public class DmGroup : Entity
	{
		public string Description { get; set; }
		public List<GroupMember> Members { get; set; } = new();
		public string ConversationURI { get; set; }//context of the federated thread
		public string ParticipantsKey { get; set; }

		public DateTime CreationDate { get; set; } = DateTime.UtcNow;
		public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
		public DateTime? DeletionAt { get; set; }

		public static string KeyOf(IEnumerable<GroupMember> members) =>
			Convert.ToHexStringLower(SHA256.HashData(Encoding.UTF8.GetBytes(string.Join("\n",
				members.Select(m => (m.IsForeign ? "remote:" : "local:") + m.AvatarId).Distinct().Order(StringComparer.Ordinal)))));
	}
}