telegram-bot/Core/Extensions/UserExtension.cs

using System.Text;
using Telegram.Bot.Types;

namespace Kruzya.TelegramBot.Core.Extensions;

public static class UserExtension
{
    public static string ToHtml(this User user, bool byUsername = false)
    {
        var text = new StringBuilder();
        text.Append($"<a href=\"tg://user?id={user.Id}\">");
           
        if (byUsername && !string.IsNullOrWhiteSpace(user.Username))
        {
            text.Append(user.Username);
        }
        else
        {
            text.Append($"{user.FirstName} {user.LastName}".Trim().HtmlEncode());
        }
        return text.Append("</a>").ToString();
    }

    public static string ToLog(this User user)
    {
        var name = $"{user.FirstName} {user.LastName}".Trim();

        return $"{name} (ID: {user.Id}, Username: {user.Username ?? "N/A"})";
    }
}