Anti flashy emoji: Take 2

Cliptok.csproj

@@ -36,6 +36,8 @@
 		<PackageReference Include="Serilog.Sinks.Console" Version="6.1.1" />
 		<PackageReference Include="Serilog.Sinks.Grafana.Loki" Version="8.3.2" />
 		<PackageReference Include="Serilog.Sinks.TextWriter" Version="3.0.0" />
+		<PackageReference Include="SkiaSharp" Version="4.148.0" />
+		<PackageReference Include="SkiaSharp.NativeAssets.Linux" Version="4.148.0" />
 		<PackageReference Include="StackExchange.Redis" Version="2.13.17" />
 		<PackageReference Include="System.Linq" Version="4.3.0" />
 		<PackageReference Include="System.Linq.Async" Version="7.0.1" />

Commands/DebugCmds.cs

@@ -9,6 +9,41 @@ public class DebugCmds
     {
         public static Dictionary<ulong, PendingUserOverride> OverridesPendingAddition = new();
 
+            [Command("gif")]
+            [Description("Debug GIF properties.")]
+            public async Task GifDebug(CommandContext ctx, string gifToCheck)
+            {
+                if (Program.cfgjson.SeizureDetection is null)
+                {
+                    await ctx.RespondAsync($"{Program.cfgjson.Emoji.Error} Seizure detection is not configured! Please check `seizureDetection` in config.json.");
+                    return;
+                }
+
+                string gifUrl;
+                var emojiMatches = Constants.RegexConstants.animoji_rx.Matches(gifToCheck);
+                if (emojiMatches.Count > 0)
+                {
+                    gifUrl = "https://cdn.discordapp.com/emojis/" + Constants.RegexConstants.id_rx.Match(emojiMatches.First().Value).Value + ".gif";
+                }
+                else
+                {
+                    gifUrl = gifToCheck;
+                }
+
+                SeizureDetectionHelpers.ImageInfo Gif = await SeizureDetectionHelpers.GetGifPropertiesAsync(gifUrl);
+                string strOut = "**GIF information**\n";
+                strOut += $"----------\nFrame count: **{Gif.FrameCount}**\n";
+                strOut += $"Unique frame count: **{Gif.UniqueFrameCount}**\n";
+                strOut += $"Average frame difference: **{Math.Round(Gif.AverageFrameDifference, 2)}**\n";
+                strOut += $"Average frame contrast: **{Math.Round(Gif.AverageContrast, 2)}**\n";
+                strOut += $"Length: **{Gif.Length}ms**\n";
+                strOut += $"Frame duration: **{Math.Round(Gif.Duration, 2)}ms**\n";
+                strOut += $"Framerate: **{Math.Round(Gif.FrameRate, 2)}fps**\n";
+                strOut += $"Seizure-inducing: **{Gif.IsSeizureInducing}**\n";
+                strOut += "----------";
+                await ctx.RespondAsync(strOut);
+            }
+
         [Command("logprint")]
         public async Task LogPrint(TextCommandContext ctx)
         {

Constants/RegexConstants.cs

@@ -21,5 +21,6 @@ public class RegexConstants
         readonly public static Regex webhook_rx = new("(?:https?:\\/\\/)?discord(?:app)?.com\\/api\\/(?:v\\d\\/)?webhooks\\/(?<id>\\d+)\\/(?<token>[A-Za-z0-9_\\-]+)", RegexOptions.ECMAScript);
         readonly public static Regex id_rx = new("[0-9]{17,}");
         readonly public static Regex image_url_rx = new(@"https:\/\/(?:(?:i\.)?imgur\.com\/(?:a\/)?[A-Za-z0-9]+(?:\.[A-Za-z]{3,4})?|i\.ibb\.co\/[A-Za-z0-9]+\/[A-Za-z0-9]+\.[A-Za-z]{3,4}|(?:cdn\.discordapp\.com|media\.discordapp\.net)\/attachments\/[0-9]{17,}\/[0-9]{17,}\/[A-Za-z0-9]+\.[A-Za-z]{3,4}\?ex=[A-Za-z0-9]+&is=[A-Za-z0-9]+&hm=[A-Za-z0-9]+&?(?:=&format=[A-Za-z0-9]+&width=[0-9]+&height=[0-9]+)?)");
+        readonly public static Regex animoji_rx = new Regex("<a:.{2,32}:[0-9]{1,32}>");
     }
 }

Events/MessageEvent.cs

@@ -329,6 +329,8 @@ public static async Task MessageHandlerAsync(DiscordClient client, MockDiscordMe
 
                     if (await RunPhishingApiFilterAsync(client, message, channel, member, permLevel, msgContentWithEmbedData, isAnEdit, limitFilters, wasAutoModBlock)) return;
 
+                    if (await RunSeizureInducingEmojiFilterAsync(client, message, channel, member, permLevel, msgContentWithEmbedData, isAnEdit, limitFilters, wasAutoModBlock)) return;
+
                     if (await RunEveryoneHerePingFilterAsync(client, message, channel, member, permLevel, msgContentWithEmbedData, isAnEdit, limitFilters, wasAutoModBlock)) return;
 
                     if (await RunMassMentionsWarnFilterAsync(client, message, channel, member, permLevel, msgContentWithEmbedData, isAnEdit, limitFilters, wasAutoModBlock)) return;
@@ -1210,6 +1212,39 @@ private static async Task<bool> RunPhishingApiFilterAsync(DiscordClient client,
             return false;
         }
 
+        private static async Task<bool> RunSeizureInducingEmojiFilterAsync(DiscordClient client, MockDiscordMessage message, DiscordChannel channel, DiscordMember member, ServerPermLevel permLevel, string msgContentWithEmbedData, bool isAnEdit, bool limitFilters, bool wasAutoModBlock)
+        {
+            if (Program.cfgjson.SeizureDetection is null)
+                return false;
+
+            var emojiMatches = animoji_rx.Matches(message.Content);
+            if (emojiMatches.Count > 0)
+            {
+                foreach (Match emoji in emojiMatches)
+                {
+                    string id = id_rx.Match(emoji.Value).Value;
+                    string url = "https://cdn.discordapp.com/emojis/" + id + ".gif";
+
+                    if ((await SeizureDetectionHelpers.GetGifPropertiesAsync(url)).IsSeizureInducing)
+                    {
+                        if (wasAutoModBlock)
+                        {
+                            Program.discord.Logger.LogDebug("AutoMod-blocked message in {channelId} by user {userId} triggered seizure-inducing emoji filter", channel.Id, message.Author.Id);
+                        }
+                        else
+                        {
+                            Program.discord.Logger.LogDebug("Message {messageId} in {channelId} by user {userId} triggered seizure-inducing emoji filter", message.Id, channel.Id, message.Author.Id);
+                        }
+
+                        await DeleteAndWarnAsync(message, "Sent a seizure-inducing emoji", client, wasAutoModBlock: wasAutoModBlock);
+                        return true;
+                    }
+                }
+            }
+
+            return false;
+        }
+
         private static async Task<bool> RunEveryoneHerePingFilterAsync(DiscordClient client, MockDiscordMessage message, DiscordChannel channel, DiscordMember member, ServerPermLevel permLevel, string messageContentOverride = default, bool isAnEdit = false, bool limitFilters = false, bool wasAutoModBlock = false)
         {
             var msgContent = message.Content;

GlobalUsings.cs

@@ -25,6 +25,7 @@
 global using Newtonsoft.Json.Linq;
 global using Serilog;
 global using Serilog.Sinks.SystemConsole.Themes;
+global using SkiaSharp;
 global using StackExchange.Redis;
 global using System;
 global using System.Collections.Generic;