From bcaaa7b3d44be3257f8b52860d59f952476bf22b Mon Sep 17 00:00:00 2001
From: billpapat <50835814+billpapat@users.noreply.github.com>
Date: Tue, 1 Jul 2025 03:07:42 +0300
Subject: [PATCH] Notify proper post deletion

Upon the deletion of a message within a help post, a system notification will be displayed, providing guidance on the proper procedure for deleting the post.
---
 .../help/HelpThreadCreatedListener.java       | 34 +++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/application/src/main/java/org/togetherjava/tjbot/features/help/HelpThreadCreatedListener.java b/application/src/main/java/org/togetherjava/tjbot/features/help/HelpThreadCreatedListener.java
index 12ee788fa1..8653a08007 100644
--- a/application/src/main/java/org/togetherjava/tjbot/features/help/HelpThreadCreatedListener.java
+++ b/application/src/main/java/org/togetherjava/tjbot/features/help/HelpThreadCreatedListener.java
@@ -11,9 +11,12 @@
 import net.dv8tion.jda.api.entities.channel.concrete.ThreadChannel;
 import net.dv8tion.jda.api.entities.channel.forums.ForumTag;
 import net.dv8tion.jda.api.events.interaction.component.ButtonInteractionEvent;
+import net.dv8tion.jda.api.events.message.MessageDeleteEvent;
 import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
 import net.dv8tion.jda.api.hooks.ListenerAdapter;
 import net.dv8tion.jda.api.requests.RestAction;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import org.togetherjava.tjbot.features.EventReceiver;
 import org.togetherjava.tjbot.features.UserInteractionType;
@@ -38,6 +41,9 @@
  */
 public final class HelpThreadCreatedListener extends ListenerAdapter
         implements EventReceiver, UserInteractor {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(HelpThreadCreatedListener.class);
+
     private final HelpSystemHelper helper;
 
     private final Cache<Long, Instant> threadIdToCreatedAtCache = Caffeine.newBuilder()
@@ -71,6 +77,34 @@ public void onMessageReceived(MessageReceivedEvent event) {
         }
     }
 
+    @Override
+    public void onMessageDelete(MessageDeleteEvent event) {
+        // Check if the deleted message was from a thread
+        if (event.isFromThread()) {
+            ThreadChannel threadChannel = event.getChannel().asThreadChannel();
+            Channel parentChannel = threadChannel.getParentChannel();
+
+            // Check if it's a help forum thread
+            if (helper.isHelpForumName(parentChannel.getName())) {
+                // Retrieve the thread owner using the owner's ID
+                long ownerId = threadChannel.getOwnerIdLong();
+                threadChannel.getGuild()
+                    .retrieveMemberById(ownerId)
+                    .queue(member -> threadChannel
+                        .sendMessage(
+                                """
+                                        It looks like a message was deleted in this help post.\s
+                                        To properly close this post, please __right-click__ on the **Created Post** __followed by__ **Delete Post**\s
+                                        instead of deleting messages. This ensures proper record-keeping and\s
+                                        helps other users find solutions.""")
+                        .queue(),
+                            failure -> LOGGER.error(
+                                    "Could not retrieve thread owner for thread ID {}: {}",
+                                    threadChannel.getId(), failure.getMessage(), failure));
+            }
+        }
+    }
+
     private boolean wasThreadAlreadyHandled(long threadChannelId) {
         // NOTE Discord/JDA fires this event twice per thread (bug?), we work around by remembering
         // the threads we already handled