telegram-bot/modules/CombotAntiSpam/UserJoinHandler.cs

using System.Text;
using System.Threading.Tasks;
using BotFramework;
using BotFramework.Attributes;
using BotFramework.Enums;
using BotFramework.Setup;
using Kruzya.TelegramBot.CombotAntiSpam.Combot;
using Kruzya.TelegramBot.Core.Extensions;
using Microsoft.Extensions.Logging;
using Telegram.Bot;
using Telegram.Bot.Types;
using Telegram.Bot.Types.Enums;

namespace Kruzya.TelegramBot.CombotAntiSpam
{
    public class UserJoinHandler : BotEventHandler
    {
        protected ICombotClient _combotClient;
        protected ILogger _logger;

        public UserJoinHandler(ICombotClient combotClient)
        {
            _combotClient = combotClient;
        }

        [Message(InChat.Public, MessageFlag.HasNewChatMembers)]
        public async Task OnUserJoined()
        {
            // var canKickMembers = (await Bot.GetChatMemberAsync(Chat, (await Bot.GetMeAsync()).Id)).CanRestrictMembers == true;
            var meUserId = (await Bot.GetMeAsync()).Id;
            var meChatMember = await Bot.GetChatMemberAsync(Chat, meUserId);

            var canKickMembers = false;
            if (meChatMember is ChatMemberAdministrator adminMember)
            {
                canKickMembers = adminMember.CanRestrictMembers;
            }

            foreach (var member in RawUpdate.Message.NewChatMembers)
            {
                if (!(await _combotClient.IsSpammerAsync(member)))
                {
                    continue;
                }
                
                var messageText = new StringBuilder();
                messageText.Append($"⚠️ <b>Combot Anti-Spam</b>\n\n");
                messageText.Append($"User {member.ToHtml()} is spammer.\n");
                messageText.Append(
                    $"More details you can find on <a href=\"https://cas.chat/query?u={member.Id}\">CAS site</a>.");
                
                await Bot.SendTextMessageAsync(Chat, messageText.ToString(), ParseMode.Html);
                
                if (canKickMembers)
                {
                    await Bot.BanChatMemberAsync(Chat, member.Id);
                }
            }
        }
    }
}