sharp-chat/SharpChat/Packet/UserConnectPacket.cs

using System;
using System.Text;

namespace SharpChat.Packet {
    public class UserConnectPacket : ServerPacket {
        public DateTimeOffset Joined { get; private set; }
        public ChatUser User { get; private set; }

        public UserConnectPacket(DateTimeOffset joined, ChatUser user) {
            Joined = joined;
            User = user ?? throw new ArgumentNullException(nameof(user));
        }

        public override string Pack() {
            StringBuilder sb = new();

            sb.Append('1');
            sb.Append('\t');
            sb.Append(Joined.ToUnixTimeSeconds());
            sb.Append('\t');
            sb.Append(User.Pack());
            sb.Append('\t');
            sb.Append(SequenceId);

            return sb.ToString();
        }
    }
}