delete blacklisted attachments from message and replace with webhook #520

ayyhimself · 2025-07-11T18:31:14Z

new crazy amazing feature where if someone sends a message with a forbidden attachment then that attachment is removed and the whole message is replaced as a webhook with only the good attachments
works server wide
config in guild config

danthe1st

Please address the changes I wrote in the review comments.

Also, please use a proper/professional commit message. You can change the commit message of your existing commit using git commit --amend (optionally with -m <message>) and then force-pushing to your branch with git push --force-with-lease.

src/main/java/net/discordjug/javabot/data/config/GuildConfig.java

src/main/java/net/discordjug/javabot/listener/BlacklistedMessageAttachmentListener.java

src/main/java/net/discordjug/javabot/util/WebhookUtil.java

danthe1st · 2025-07-11T18:57:39Z

Please also fix the checkstyle errors. We use tabs for indentation.

src/main/java/net/discordjug/javabot/listener/BlacklistedMessageAttachmentListener.java

danthe1st

Please see the comments.

Other things to eventually convert to a filter:

AutoMod (please do this in this PR)
suggestions (can be another PR)
code formatting in help channel (can be in another PR)

It might als be a good idea to add an overload to WebhookUtil.replaceMessage without embeds/attachments to make the code simpler instead of having to add a null argument wherever calling it.

danthe1st · 2025-08-03T15:08:45Z

src/main/java/net/discordjug/javabot/data/config/GuildConfig.java

@@ -18,7 +18,10 @@
 import java.lang.reflect.Field;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.HashSet;


HashSet and List shouldn't be needed (I think the CI would complain about that)

danthe1st · 2025-08-03T15:12:48Z

src/main/java/net/discordjug/javabot/listener/handler/MessageFormatFilter.java

+import java.util.List;
+
+public interface MessageFormatFilter {
+    boolean processMessage(MessageReceivedEvent event, StringBuilder builder, List<Message.Attachment> attachments, List<MessageEmbed> embeds);


Please create one data class (probably a record is the best choice) to store the content StringBuilder, the current attachments and the embeds and pass that.

That makes it easier to add additional contents that should be changed without modifying every filter.

danthe1st · 2025-08-03T15:16:43Z

src/main/java/net/discordjug/javabot/listener/handler/MessageFormatFilter.java

+import java.util.List;
+
+public interface MessageFormatFilter {
+    boolean processMessage(MessageReceivedEvent event, StringBuilder builder, List<Message.Attachment> attachments, List<MessageEmbed> embeds);


A boolean return type will probably not be sufficient as it will probably be necessary to indicate the message being removed as well for things like converting automod to a filter.
An enum or record would likely be a better choice.

danthe1st · 2025-08-03T15:19:05Z

src/main/java/net/discordjug/javabot/listener/handler/HugFilter.java

+    @Override
+    public boolean processMessage(MessageReceivedEvent event, StringBuilder builder, List<Message.Attachment> attachments, List<MessageEmbed> embeds) {
+        replaceFucks(builder);
+        return true;


Why does this always return true independently of whether the message has been modified?

danthe1st · 2025-08-03T15:32:41Z

src/main/java/net/discordjug/javabot/listener/handler/HugFilter.java

+    }
+
+    public static void replaceFucks(StringBuilder sb) {
+        Matcher matcher = FUCKER.matcher(sb);


Matcher doesn't seem to expect the CharSequence to be modified during the matching (until the find()s are complete). Please change this to FUCKER.matcher(sb.toString()) (or similar).

example code showing that Matcher doesn't expect it to be modified:

StringBuilder sb = new StringBuilder("aba"); Matcher matcher = Pattern.compile("a").matcher(sb); sb.insert(0,"xyz");//xyzaba if(matcher.find()) { // false // alternatively move the sb.insert(0,"xyz"); here to see to break even more System.out.println(matcher.start()); System.out.println(matcher.group()); }

Aside from that, I think the easiest (and most robust) approach would be to keep the existing logic using Matcher#replaceAll and replace the StringBuilder content if the returned String is different (or alternatively use if(matcher.find()) with matcher.replaceAll(...) inside).

danthe1st · 2025-08-03T15:52:31Z

src/main/java/net/discordjug/javabot/listener/handler/MessageFormatHandler.java

+
+        for (MessageFormatFilter filter : filters) {
+            boolean processed = filter.processMessage(event, builder, attachments, embeds);
+            if (processed) {


Alternatively, this could be handled |= filter.processMessage() but since you'll need multiple states for automod (filter execution aborted), that's probably irrelevant.

danthe1st · 2025-08-03T15:54:02Z

src/main/java/net/discordjug/javabot/listener/handler/MessageFormatHandler.java

+            if (webhookContainer == null) {
+                return;
+            }
+            replaceMessage(event, webhookContainer, builder.toString(), threadId, attachments, embeds);


I assume this works correctly with initial forum posts (i.e. the first message in a forum post/thread)?

danthe1st · 2025-08-03T15:54:59Z

src/main/java/net/discordjug/javabot/listener/handler/MessageFormatHandler.java

+    }
+
+    private static void replaceMessage(@NotNull MessageReceivedEvent event, IWebhookContainer webhookContainer,
+                                       String messageContentRaw, long threadId, List<Message.Attachment> attachments,


When using a record for these parameters, it would be good to pass the record until here btw.

danthe1st · 2025-08-03T16:00:05Z

src/main/java/net/discordjug/javabot/util/WebhookUtil.java

 	}

 	private static CompletableFuture<ReadonlyMessage> mirrorMessageToWebhook(@NotNull Webhook webhook, Message originalMessage, String newMessageContent, long threadId,
-			List<LayoutComponent> components, List<MessageEmbed> embeds, Member member) {
+																			 List<LayoutComponent> components, List<Message.Attachment> attachments, List<MessageEmbed> embeds, Member member) {


I see a whitespace change here and a bit above. Is there a reason for this?

danthe1st · 2025-08-03T16:00:46Z

src/main/java/net/discordjug/javabot/util/WebhookUtil.java

@@ -118,11 +118,12 @@ private static CompletableFuture<ReadonlyMessage> mirrorMessageToWebhook(@NotNul
 		message.addEmbeds(embeds.stream()
 				.map(e -> WebhookEmbedBuilder.fromJDA(e).build())
 				.toList());
-		List<Attachment> attachments = originalMessage.getAttachments();
+		List<Attachment> newAttachments = attachments != null ? attachments : originalMessage.getAttachments();
+		System.out.println(newAttachments.size());


Please remove this use of System.out.

danthe1st · 2025-08-03T16:10:04Z

src/main/java/net/discordjug/javabot/listener/handler/MessageFormatHandler.java

+                ),
+                e -> ExceptionLogger.capture(
+                        e,
+                        "Error creating webhook for BlacklistedMessageAttachmentListener"


This isn't BlacklistedMessageAttachmentListener any more ;)
You can use getClass().getSimpleName().

ayyhimself requested a review from a team as a code owner July 11, 2025 18:31

danthe1st requested changes Jul 11, 2025

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danthe1st reviewed Jul 12, 2025

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src/main/java/net/discordjug/javabot/listener/BlacklistedMessageAttachmentListener.java Outdated Show resolved Hide resolved

add message format handler and message attachment filter

a2b3d33

ayyhimself force-pushed the ayys-crazy-attachment-remover branch from 699283b to a2b3d33 Compare August 3, 2025 15:07

danthe1st requested changes Aug 3, 2025

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danthe1st reviewed Aug 3, 2025

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delete blacklisted attachments from message and replace with webhook #520

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delete blacklisted attachments from message and replace with webhook #520

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ayyhimself commented Jul 11, 2025

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danthe1st commented Jul 11, 2025

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