From 520f1efe376f7b704a1c15ff70e1c86e0695241f Mon Sep 17 00:00:00 2001
From: Sergey Gut <kruzefag@gmail.com>
Date: Wed, 16 Feb 2022 19:44:53 +0300
Subject: [PATCH] AntiFlood service

---
 Core/Service/IAntiFlood.cs               |  9 ++++
 Core/Service/MemoryAntiFloodService.cs   | 63 ++++++++++++++++++++++++
 Core/Startup.cs                          |  1 +
 modules/Reputation/Handler/Reputation.cs | 20 ++++++--
 4 files changed, 89 insertions(+), 4 deletions(-)
 create mode 100644 Core/Service/IAntiFlood.cs
 create mode 100644 Core/Service/MemoryAntiFloodService.cs

diff --git a/Core/Service/IAntiFlood.cs b/Core/Service/IAntiFlood.cs
new file mode 100644
index 0000000..f8fec33
--- /dev/null
+++ b/Core/Service/IAntiFlood.cs
@@ -0,0 +1,9 @@
+using Telegram.Bot.Types;
+
+namespace Kruzya.TelegramBot.Core.Service;
+
+public interface IAntiFlood
+{
+    public bool IsUserFlooding(Chat chat, User user);
+    public void RecordAction(Chat chat, User user);
+}
diff --git a/Core/Service/MemoryAntiFloodService.cs b/Core/Service/MemoryAntiFloodService.cs
new file mode 100644
index 0000000..ce5086b
--- /dev/null
+++ b/Core/Service/MemoryAntiFloodService.cs
@@ -0,0 +1,63 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.Extensions.Configuration;
+using Telegram.Bot.Types;
+
+namespace Kruzya.TelegramBot.Core.Service;
+
+public class MemoryAntiFloodService : IAntiFlood
+{
+    private IDictionary<string, IList<DateTime>> _floodUsers;
+    private IDictionary<string, DateTime> _bannedUsers;
+    private int _floodStartsAfter = 3;
+    private TimeSpan _banningTimeSpan; 
+
+    public MemoryAntiFloodService(IConfiguration configuration)
+    {
+        _floodUsers = new Dictionary<string, IList<DateTime>>();
+        _bannedUsers = new Dictionary<string, DateTime>();
+        _floodStartsAfter = configuration.GetValue<int>("FloodActions");
+        _banningTimeSpan = TimeSpan.FromMinutes(configuration.GetValue<double>("FloodBanTime"));
+    }
+
+    public bool IsUserFlooding(Chat chat, User user)
+    {
+        var dictKey = DictKey(chat, user);
+        if (_bannedUsers.TryGetValue(dictKey, out var expirationTime))
+        {
+            if (DateTime.UtcNow <= expirationTime)
+            {
+                expirationTime = DateTime.MinValue;
+                _bannedUsers.Remove(dictKey);
+            }
+        }
+
+        return (DateTime.UtcNow >= expirationTime);
+    }
+
+    public void RecordAction(Chat chat, User user)
+    {
+        var dictKey = DictKey(chat, user);
+        if (!_floodUsers.TryGetValue(dictKey, out var actionTimeList))
+        {
+            actionTimeList = new List<DateTime>();
+        }
+
+        actionTimeList.Add(DateTime.UtcNow);
+        actionTimeList = actionTimeList.Where(e => e.Subtract(_banningTimeSpan) <= DateTime.UtcNow).ToList();
+        _floodUsers[dictKey] = actionTimeList;
+
+        if (actionTimeList.Count > _floodStartsAfter)
+        {
+            actionTimeList.Clear();
+            _bannedUsers[dictKey] = DateTime.UtcNow.Add(_banningTimeSpan);
+        }
+    }
+
+    private string DictKey(Chat chat, User user)
+    {
+        return $"{chat.Id}-{user.Id}";
+    }
+}
diff --git a/Core/Startup.cs b/Core/Startup.cs
index 361929c..cee6101 100644
--- a/Core/Startup.cs
+++ b/Core/Startup.cs
@@ -43,6 +43,7 @@ namespace Kruzya.TelegramBot.Core
             services.AddSingleton<ICacheStorage<long, User>, MemoryCache<long, User>>();
 
             services.AddSingleton<UserService>();
+            services.AddSingleton<IAntiFlood, MemoryAntiFloodService>();
 
             // Trigger module handlers.
             _core.Modules.ConfigureServices(services);
diff --git a/modules/Reputation/Handler/Reputation.cs b/modules/Reputation/Handler/Reputation.cs
index 71c24d6..36cd87b 100644
--- a/modules/Reputation/Handler/Reputation.cs
+++ b/modules/Reputation/Handler/Reputation.cs
@@ -19,6 +19,7 @@ public class Reputation : CommonHandler
     private readonly UserService _userService;
     private readonly ILogger _logger;
     private readonly IReputation _reputationService;
+    private readonly IAntiFlood _antiFlood;
 
     private static readonly List<string> RepUpChars = new()
     {
@@ -45,10 +46,12 @@ public class Reputation : CommonHandler
         CoreContext db, 
         UserService userService, 
         IReputation reputationService,
+        IAntiFlood antiFlood,
         ILogger<Reputation> logger) : base(db)
     {
         _reputationService = reputationService;
         _userService = userService;
+        _antiFlood = antiFlood;
         _logger = logger;
     }
 
@@ -56,7 +59,7 @@ public class Reputation : CommonHandler
     public async Task HandleReputation()
     {
         var text = Message?.Text;
-            
+
         if (string.IsNullOrEmpty(text))
         {
             text = Message?.Sticker?.Emoji;
@@ -65,14 +68,23 @@ public class Reputation : CommonHandler
         {
             return;
         }
-            
+
         var receiver = RepliedUser;
         var canChangeRep = receiver is { IsBot: false } && !From.IsBot && receiver.Id != From.Id;
            
         if (canChangeRep && (RepUpChars.Contains(text) || RepDownChars.Contains(text)))
         {
-            var senderRepCount = await GetUserReputation(From);
+            if (!_userService.IsUserSuper(From))
+            {
+                if (_antiFlood.IsUserFlooding(Chat, From))
+                {
+                    return;
+                }
 
+                _antiFlood.RecordAction(Chat, From);
+            }
+
+            var senderRepCount = await GetUserReputation(From);
             if (senderRepCount < 0)
             {
                 await Reply(new HtmlString()
@@ -143,7 +155,7 @@ public class Reputation : CommonHandler
             i++;
         }
 
-        await Bot.SendTextMessageAsync(Chat, msg.ToString(), ParseMode.Html,
+        await Bot.SendTextMessageAsync(Chat!, msg.ToString(), ParseMode.Html,
             disableNotification: true);
     }