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(true)} 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: ParseMode.Html);
                
            if (canKickMembers)
            {
                await Bot.BanChatMemberAsync(Chat, member.Id);
            }
        }
    }
}