🚧 Anti-spam system based on entities

Core/Core.cs

@@ -165,7 +165,7 @@ namespace Kruzya.TelegramBot.Core
             appDomain.AssemblyResolve += delegate(object? sender, ResolveEventArgs args)
             {
                 var basePath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
-                string assemblyPath = Path.Combine(basePath, new AssemblyName(args.Name).Name + ".dll");
+                var assemblyPath = Path.Combine(basePath, new AssemblyName(args.Name).Name + ".dll");
                 if (!File.Exists(assemblyPath))
                 {
                     return null;

Core/Extensions/StartupExtension.cs

@@ -1,4 +1,5 @@
 using System.Collections.Concurrent;
+using Kruzya.TelegramBot.Core.Cache;
 using Microsoft.Extensions.DependencyInjection;
 
 namespace Kruzya.TelegramBot.Core.Extensions
@@ -7,5 +8,8 @@ namespace Kruzya.TelegramBot.Core.Extensions
     {
         public static IServiceCollection AddQueue<T>(this IServiceCollection collection)
             => collection.AddSingleton<ConcurrentQueue<T>>();
+
+        public static IServiceCollection AddMemoryCache<TKey, TValue>(this IServiceCollection collection)
+            => collection.AddSingleton<MemoryCache<TKey, TValue>>();
     }
 }

Core/Extensions/UserExtension.cs

@@ -8,7 +8,7 @@ namespace Kruzya.TelegramBot.Core.Extensions
         public static string ToHtml(this User user)
         {
             var text = new StringBuilder();
-            text.Append("<a href=\"tg://user?id={member.Id}\">");
+            text.Append($"<a href=\"tg://user?id={user.Id}\">");
             if (!string.IsNullOrWhiteSpace(user.Username))
                 text.Append(user.Username);
             else

Kruzya.TelegramBot.sln

@@ -10,6 +10,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "RichSiteSummary", "modules\
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Tests", "tests\Tests.csproj", "{5C62CA70-F270-4029-953E-458623C31A3B}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "UrlLimitations", "modules\UrlLimitations\UrlLimitations.csproj", "{B82E3339-3B34-4600-8C59-C5A3640B1982}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -32,9 +34,14 @@ Global
 		{5C62CA70-F270-4029-953E-458623C31A3B}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{5C62CA70-F270-4029-953E-458623C31A3B}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{5C62CA70-F270-4029-953E-458623C31A3B}.Release|Any CPU.Build.0 = Release|Any CPU
+		{B82E3339-3B34-4600-8C59-C5A3640B1982}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{B82E3339-3B34-4600-8C59-C5A3640B1982}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{B82E3339-3B34-4600-8C59-C5A3640B1982}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{B82E3339-3B34-4600-8C59-C5A3640B1982}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
 		{F1E1FBB7-ABA4-4304-9A42-D4975822B002} = {C7821F15-DEDD-474F-A575-A296D4B58F10}
 		{C50D64C3-204B-4B58-927B-C8D759787252} = {C7821F15-DEDD-474F-A575-A296D4B58F10}
+		{B82E3339-3B34-4600-8C59-C5A3640B1982} = {C7821F15-DEDD-474F-A575-A296D4B58F10}
 	EndGlobalSection
 EndGlobal

modules/UrlLimitations/Data/ChatMember.cs

@@ -0,0 +1,19 @@
+using Telegram.Bot.Types;
+
+namespace Kruzya.TelegramBot.UrlLimitations
+{
+    public struct ChatMember
+    {
+        public long Chat;
+        public long User;
+
+        public static ChatMember From(long chatId, long userId)
+        {
+            return new ChatMember()
+            {
+                Chat = chatId,
+                User = userId
+            };
+        }
+    }
+}

modules/UrlLimitations/MessageHandler.cs

@@ -0,0 +1,58 @@
+using System;
+using System.Linq;
+using System.Threading.Tasks;
+using BotFramework;
+using BotFramework.Attributes;
+using BotFramework.Setup;
+using Kruzya.TelegramBot.Core.Cache;
+using Kruzya.TelegramBot.Core.Extensions;
+using Microsoft.Extensions.Logging;
+using Telegram.Bot.Types;
+using Telegram.Bot.Types.Enums;
+
+namespace Kruzya.TelegramBot.UrlLimitations
+{
+    public class MessageHandler : BotEventHandler
+    {
+        protected ILogger Logger;
+        protected MemoryCache<ChatMember, UInt16> ChatMembersCache;
+
+        public MessageHandler(ILogger<MessageHandler> logger, MemoryCache<ChatMember, UInt16> chatMembersCache)
+        {
+            Logger = logger;
+            ChatMembersCache = chatMembersCache;
+        }
+
+        [TextMessage(InChat.Public)]
+        public async Task OnMessageReceived()
+        {
+            Logger.LogDebug($"Message received from {From.Id} in {Chat.Id}");
+
+            UInt16 messageCount;
+            var chatMember = ChatMember.From(Chat.Id, From.Id);
+            if (!ChatMembersCache.TryGetValue(chatMember, out messageCount))
+            {
+                return;
+            }
+
+            if (messageCount > 10)
+            {
+                ChatMembersCache.SetValue(chatMember, 0, 0);
+                return;
+            }
+
+            messageCount++;
+            ChatMembersCache.SetValue(chatMember, messageCount);
+            var message = RawUpdate.Message;
+            if (message.Entities.Count(e => e.Type == MessageEntityType.Url || e.Type == MessageEntityType.TextLink) >
+                0)
+            {
+                var targetChat = new ChatId(Chat.Id);
+                await Bot.KickChatMemberAsync(new ChatId(Chat.Id), From.Id, DateTime.Now.AddDays(1));
+                await Bot.DeleteMessageAsync(targetChat, message.MessageId);
+                await Bot.SendTextMessageAsync(targetChat,
+                    $"Member {From.ToHtml()} has been banned.\n<b>Reason</b>: <pre>Spam suspicion</pre>", ParseMode.Html);
+            }
+        }
+    }
+}

modules/UrlLimitations/UrlLimitations.cs

@@ -0,0 +1,19 @@
+using System;
+using Kruzya.TelegramBot.Core;
+using Kruzya.TelegramBot.Core.Extensions;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Kruzya.TelegramBot.UrlLimitations
+{
+    public class UrlLimitations : Module
+    {
+        public UrlLimitations(Core.Core core) : base(core)
+        {
+        }
+
+        public override void ConfigureServices(IServiceCollection services)
+        {
+            services.AddMemoryCache<ChatMember, UInt16>();
+        }
+    }
+}

modules/UrlLimitations/UrlLimitations.csproj

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>netcoreapp3.1</TargetFramework>
+        <AssemblyName>TelegramBot.UrlLimitations</AssemblyName>
+        <RootNamespace>Kruzya.TelegramBot.UrlLimitations</RootNamespace>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <ProjectReference Include="..\..\Core\Core.csproj" />
+    </ItemGroup>
+
+</Project>

modules/UrlLimitations/UserJoinHandler.cs

@@ -0,0 +1,25 @@
+using System;
+using BotFramework;
+using BotFramework.Attributes;
+using BotFramework.Setup;
+using Kruzya.TelegramBot.Core.Cache;
+using Telegram.Bot.Types.Enums;
+
+namespace Kruzya.TelegramBot.UrlLimitations
+{
+    public class UserJoinHandler : BotEventHandler
+    {
+        protected MemoryCache<ChatMember, UInt16> ChatMembersCache;
+        
+        public UserJoinHandler(MemoryCache<ChatMember, UInt16> chatMembersCache)
+        {
+            ChatMembersCache = chatMembersCache;
+        }
+        
+        [Message(MessageType.ChatMembersAdded, InChat.Public)]
+        public void OnChatMembersAdded()
+        {
+            ChatMembersCache.SetValue(ChatMember.From(Chat.Id, From.Id), 0);
+        }
+    }
+}