telegram-bot/Core/GeneralHandler.cs

using System;
using System.Linq;
using System.Threading.Tasks;
using BotFramework;
using BotFramework.Attributes;
using Kruzya.TelegramBot.Core.Data;
using Microsoft.EntityFrameworkCore;
using Telegram.Bot.Types;

namespace Kruzya.TelegramBot.Core
{
    public class GeneralHandler : BotEventHandler
    {
        [AttributeUsage(AttributeTargets.Method)]
        public sealed class HandleEverythingAttribute : HandlerAttribute
        {
            protected override bool CanHandle(HandlerParams param)
            {
                return true;
            }
        }

        protected readonly CoreContext databaseContext;
        
        public GeneralHandler(CoreContext dbCtx)
        {
            databaseContext = dbCtx;
        }

        [HandleEverything]
        public async Task Listener()
        {
            foreach (var message in new Message[] {RawUpdate.Message, RawUpdate.EditedMessage, RawUpdate.ChannelPost, RawUpdate.EditedChannelPost})
            {
                if (message == null)
                {
                    continue;
                }

                await VerifyChatPair(message);
            }
            
            throw new ArgumentException();
        }

        public async Task VerifyChatPair(Message message)
        {
            await VerifyChatPair(message.Chat, message.From);
        }

        public async Task VerifyChatPair(Chat chat, User user)
        {
            await VerifyChatPair(chat.Id, user.Id);
        }

        public async Task VerifyChatPair(long chat, int user)
        {
            var hasEntry = await databaseContext.Users.AnyAsync(e => e.ChatId == chat && e.UserId == user);
            if (hasEntry)
            {
                return;
            }

            await MakeChatPair(chat, user);
        }

        public async Task MakeChatPair(long chat, int user)
        {
            await databaseContext.Users.AddAsync(new BotUser()
            {
                ChatId = chat,
                UserId = user,
                BotUserId = new Guid()
            });
        }
    }
}