fix: AI message dismiss button (#1403)

* fix: AI message dismiss button

when message that created thread was deleted,
retrieveStartMessage() threw an error UNKNOWN_MESSAGE
leading to non-functional dismiss button.

this adds a handler, specifically for parent message
deleted error by using getIterableHistoryInstead.

* refactor: HelpThreadCreatedListener

* move AI dismiss fallback consumer to a seperate function for clarity
* move variable FIRST_MESSAGE_ONLY to function scope as noOfMessage for
  clarity
* improve error log message for clarity

Author: ankitsmt211

application/src/main/java/org/togetherjava/tjbot/features/help/HelpThreadCreatedListener.java

@@ -12,8 +12,12 @@
 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.MessageReceivedEvent;
+import net.dv8tion.jda.api.exceptions.ErrorResponseException;
 import net.dv8tion.jda.api.hooks.ListenerAdapter;
+import net.dv8tion.jda.api.requests.ErrorResponse;
 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;
@@ -28,8 +32,10 @@
 import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.TimeUnit;
+import java.util.function.Consumer;
 import java.util.stream.Collectors;
 
+
 /**
  * Listens for new help threads being created. That is, a user posted a question in the help forum.
  * <p>
@@ -38,6 +44,7 @@
  */
 public final class HelpThreadCreatedListener extends ListenerAdapter
         implements EventReceiver, UserInteractor {
+    private static final Logger log = LoggerFactory.getLogger(HelpThreadCreatedListener.class);
     private final HelpSystemHelper helper;
 
     private final Cache<Long, Instant> threadIdToCreatedAtCache = Caffeine.newBuilder()
@@ -159,6 +166,25 @@ public void acceptComponentIdGenerator(ComponentIdGenerator generator) {
         componentIdInteractor.acceptComponentIdGenerator(generator);
     }
 
+    private Consumer<Throwable> handleParentMessageDeleted(Member user, ThreadChannel channel,
+            ButtonInteractionEvent event, List<String> args) {
+        int noOfMessages = 1; // we only care about first message from channel history
+        return error -> {
+            if (error instanceof ErrorResponseException ere
+                    && ere.getErrorResponse() == ErrorResponse.UNKNOWN_MESSAGE) {
+                channel.getIterableHistory().reverse().limit(noOfMessages).queue(messages -> {
+                    if (!messages.isEmpty()) {
+                        handleDismiss(user, channel, messages.getFirst(), event, args);
+                    }
+                });
+            } else {
+                log.error(
+                        "Trying to dismiss AI help message for thread: {}, unable to find original message.",
+                        channel.getId(), error);
+            }
+        };
+    }
+
     @Override
     public void onButtonClick(ButtonInteractionEvent event, List<String> args) {
         // This method handles chatgpt's automatic response "dismiss" button
@@ -169,7 +195,8 @@ public void onButtonClick(ButtonInteractionEvent event, List<String> args) {
 
         channel.retrieveStartMessage()
             .queue(forumPostMessage -> handleDismiss(interactionUser, channel, forumPostMessage,
-                    event, args));
+                    event, args),
+                    handleParentMessageDeleted(interactionUser, channel, event, args));
 
     }