Fixed bugs with rate limiting by adding cooldown

* close command
* change category command

application/src/main/java/org/togetherjava/tjbot/commands/help/ChangeHelpCategoryCommand.java

@@ -1,5 +1,7 @@
 package org.togetherjava.tjbot.commands.help;
 
+import com.github.benmanes.caffeine.cache.Cache;
+import com.github.benmanes.caffeine.cache.Caffeine;
 import net.dv8tion.jda.api.entities.Guild;
 import net.dv8tion.jda.api.entities.Message;
 import net.dv8tion.jda.api.entities.Role;
@@ -14,7 +16,10 @@
 import org.togetherjava.tjbot.commands.SlashCommandVisibility;
 import org.togetherjava.tjbot.config.Config;
 
+import java.time.Instant;
+import java.time.temporal.ChronoUnit;
 import java.util.Optional;
+import java.util.concurrent.TimeUnit;
 
 /**
  * Implements the {@code /change-help-category} command, which is able to change the category of a
@@ -29,7 +34,11 @@
 public final class ChangeHelpCategoryCommand extends SlashCommandAdapter {
     private static final String CATEGORY_OPTION = "category";
 
+    private static final int COOLDOWN_DURATION_VALUE = 1;
+    private static final ChronoUnit COOLDOWN_DURATION_UNIT = ChronoUnit.HOURS;
+
     private final HelpSystemHelper helper;
+    private final Cache<Long, Instant> helpThreadIdToLastCategoryChange;
 
     /**
      * Creates a new instance.
@@ -49,6 +58,11 @@ public ChangeHelpCategoryCommand(@NotNull Config config, @NotNull HelpSystemHelp
 
         getData().addOptions(category);
 
+        helpThreadIdToLastCategoryChange = Caffeine.newBuilder()
+            .maximumSize(1_000)
+            .expireAfterAccess(COOLDOWN_DURATION_VALUE, TimeUnit.of(COOLDOWN_DURATION_UNIT))
+            .build();
+
         this.helper = helper;
     }
 
@@ -66,6 +80,16 @@ public void onSlashCommand(@NotNull SlashCommandInteractionEvent event) {
             return;
         }
 
+        if (isHelpThreadOnCooldown(helpThread)) {
+            event
+                .reply("Please wait a bit, this command can only be used once per %d %s."
+                    .formatted(COOLDOWN_DURATION_VALUE, COOLDOWN_DURATION_UNIT))
+                .setEphemeral(true)
+                .queue();
+            return;
+        }
+        helpThreadIdToLastCategoryChange.put(helpThread.getIdLong(), Instant.now());
+
         event.deferReply().queue();
 
         helper.renameChannelToCategoryTitle(helpThread, category)
@@ -96,4 +120,13 @@ public void onSlashCommand(@NotNull SlashCommandInteractionEvent event) {
         return action.flatMap(any -> helpThread.sendMessage(headsUpWithoutRole)
             .flatMap(message -> message.editMessage(headsUpWithRole)));
     }
+
+    private boolean isHelpThreadOnCooldown(@NotNull ThreadChannel helpThread) {
+        return Optional
+            .ofNullable(helpThreadIdToLastCategoryChange.getIfPresent(helpThread.getIdLong()))
+            .map(lastCategoryChange -> lastCategoryChange.plus(COOLDOWN_DURATION_VALUE,
+                    COOLDOWN_DURATION_UNIT))
+            .filter(Instant.now()::isBefore)
+            .isPresent();
+    }
 }

application/src/main/java/org/togetherjava/tjbot/commands/help/CloseCommand.java

@@ -1,5 +1,7 @@
 package org.togetherjava.tjbot.commands.help;
 
+import com.github.benmanes.caffeine.cache.Cache;
+import com.github.benmanes.caffeine.cache.Caffeine;
 import net.dv8tion.jda.api.EmbedBuilder;
 import net.dv8tion.jda.api.entities.MessageEmbed;
 import net.dv8tion.jda.api.entities.ThreadChannel;
@@ -8,14 +10,23 @@
 import org.togetherjava.tjbot.commands.SlashCommandAdapter;
 import org.togetherjava.tjbot.commands.SlashCommandVisibility;
 
+import java.time.Instant;
+import java.time.temporal.ChronoUnit;
+import java.util.Optional;
+import java.util.concurrent.TimeUnit;
+
 /**
  * Implements the {@code /close} command to close question threads.
  * <p>
  * Can be used in active (non-archived) question threads. Will close, i.e. archive, the thread upon
  * use. Meant to be used once a question has been resolved.
  */
 public final class CloseCommand extends SlashCommandAdapter {
+    private static final int COOLDOWN_DURATION_VALUE = 1;
+    private static final ChronoUnit COOLDOWN_DURATION_UNIT = ChronoUnit.HOURS;
+
     private final HelpSystemHelper helper;
+    private final Cache<Long, Instant> helpThreadIdToLastClose;
 
     /**
      * Creates a new instance.
@@ -25,6 +36,11 @@ public final class CloseCommand extends SlashCommandAdapter {
     public CloseCommand(@NotNull HelpSystemHelper helper) {
         super("close", "Close this question thread", SlashCommandVisibility.GUILD);
 
+        helpThreadIdToLastClose = Caffeine.newBuilder()
+            .maximumSize(1_000)
+            .expireAfterAccess(COOLDOWN_DURATION_VALUE, TimeUnit.of(COOLDOWN_DURATION_UNIT))
+            .build();
+
         this.helper = helper;
     }
 
@@ -40,10 +56,28 @@ public void onSlashCommand(@NotNull SlashCommandInteractionEvent event) {
             return;
         }
 
+        if (isHelpThreadOnCooldown(helpThread)) {
+            event
+                .reply("Please wait a bit, this command can only be used once per %d %s."
+                    .formatted(COOLDOWN_DURATION_VALUE, COOLDOWN_DURATION_UNIT))
+                .setEphemeral(true)
+                .queue();
+            return;
+        }
+        helpThreadIdToLastClose.put(helpThread.getIdLong(), Instant.now());
+
         MessageEmbed embed = new EmbedBuilder().setDescription("Closed the thread.")
             .setColor(HelpSystemHelper.AMBIENT_COLOR)
             .build();
 
         event.replyEmbeds(embed).flatMap(any -> helpThread.getManager().setArchived(true)).queue();
     }
+
+    private boolean isHelpThreadOnCooldown(@NotNull ThreadChannel helpThread) {
+        return Optional.ofNullable(helpThreadIdToLastClose.getIfPresent(helpThread.getIdLong()))
+            .map(lastCategoryChange -> lastCategoryChange.plus(COOLDOWN_DURATION_VALUE,
+                    COOLDOWN_DURATION_UNIT))
+            .filter(Instant.now()::isBefore)
+            .isPresent();
+    }
 }