sharp-chat/SharpChat/Packet/ChatMessageAddPacket.cs

using System.Text;

namespace SharpChat.Packet {
    public class ChatMessageAddPacket(
        long msgId,
        DateTimeOffset created,
        long userId,
        string text,
        bool isAction,
        bool isPrivate
    ) : IServerPacket {
        public string Text { get; } = text ?? throw new ArgumentNullException(nameof(text));

        public IEnumerable<string> Pack() {
            StringBuilder sb = new();

            sb.Append('2');
            sb.Append('\t');

            sb.Append(created.ToUnixTimeSeconds());
            sb.Append('\t');

            sb.Append(userId);
            sb.Append('\t');

            if(isAction)
                sb.Append("<i>");

            sb.Append(
                Text.Replace("<", "&lt;")
                    .Replace(">", "&gt;")
                    .Replace("\n", " <br/> ")
                    .Replace("\t", "    ")
            );

            if(isAction)
                sb.Append("</i>");

            sb.Append('\t');
            sb.Append(msgId);
            sb.AppendFormat(
                "\t1{0}0{1}{2}",
                isAction ? '1' : '0',
                isAction ? '0' : '1',
                isPrivate ? '1' : '0'
            );

            yield return sb.ToString();
        }
    }
}