Archive instead of simply deleting voice channels

Currently there is no way to moderate ephemeral voice channels. Members
could very easily break the rules in the channel, send NSFW content and
it can go undetected by the moderation team.

Introduce a new archival system where the ephemeral voice channels are
instead stored in an archival category.

Depending on the archival strategy, channels are removed once they are
not needed any more.

Routines are not being used since we are able to get away with
attempting cleanup every time a user leaves an ephemeral voice channel.

This results in superior performance and no scheduling involved.

Do _not_ archive ephemeral voice channels with no contents sent by
members.

Signed-off-by: Chris Sdogkos <work@chris-sdogkos.com>

Author: christolis

application/src/main/java/org/togetherjava/tjbot/features/voicechat/DynamicVoiceChat.java

@@ -4,10 +4,14 @@
 import net.dv8tion.jda.api.entities.Guild;
 import net.dv8tion.jda.api.entities.Member;
 import net.dv8tion.jda.api.entities.MessageEmbed;
+import net.dv8tion.jda.api.entities.MessageHistory;
+import net.dv8tion.jda.api.entities.channel.concrete.Category;
 import net.dv8tion.jda.api.entities.channel.concrete.VoiceChannel;
 import net.dv8tion.jda.api.entities.channel.middleman.AudioChannel;
 import net.dv8tion.jda.api.entities.channel.unions.AudioChannelUnion;
 import net.dv8tion.jda.api.events.guild.voice.GuildVoiceUpdateEvent;
+import net.dv8tion.jda.api.managers.channel.middleman.AudioChannelManager;
+import net.dv8tion.jda.api.requests.RestAction;
 import org.jetbrains.annotations.NotNull;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -16,21 +20,34 @@
 import org.togetherjava.tjbot.features.VoiceReceiverAdapter;
 
 import java.util.List;
+import java.util.Optional;
 import java.util.regex.Pattern;
 
 /**
  * Handles dynamic voice channel creation and deletion based on user activity.
  * <p>
  * When a member joins a configured root channel, a temporary copy is created and the member is
- * moved into it. Once the channel becomes empty, it is deleted.
+ * moved into it. Once the channel becomes empty, it is archived and further deleted using a
+ * {@link VoiceChatCleanupStrategy}.
  */
 public final class DynamicVoiceChat extends VoiceReceiverAdapter {
     private static final Logger logger = LoggerFactory.getLogger(DynamicVoiceChat.class);
+
+    // @christolis: Unless somebody is willing to make the category name configurable,
+    // I will leave this here as a constant since I don't see a justification for naming
+    // this category name into something different.
+    private static final String ARCHIVE_CATEGORY_NAME = "Voice Channel Archives";
+    private static final int CLEAN_CHANNELS_AMOUNT = 2;
+    private static final int MINIMUM_CHANNELS_AMOUNT = 3;
+
+    private final VoiceChatCleanupStrategy voiceChatCleanupStrategy;
     private final List<Pattern> dynamicVoiceChannelPatterns;
 
     public DynamicVoiceChat(Config config) {
         this.dynamicVoiceChannelPatterns =
                 config.getDynamicVoiceChannelPatterns().stream().map(Pattern::compile).toList();
+        this.voiceChatCleanupStrategy =
+                new OldestVoiceChatCleanup(CLEAN_CHANNELS_AMOUNT, MINIMUM_CHANNELS_AMOUNT);
     }
 
     @Override
@@ -45,7 +62,17 @@ public void onVoiceUpdate(@NotNull GuildVoiceUpdateEvent event) {
 
         if (channelLeft != null && !eventHappenOnDynamicRootChannel(channelLeft)) {
             logger.debug("Event happened on left channel {}", channelLeft);
-            deleteDynamicVoiceChannel(channelLeft);
+
+            MessageHistory messageHistory = channelLeft.asVoiceChannel().getHistory();
+            messageHistory.retrievePast(2).queue(messages -> {
+                // Don't forget that there is always one
+                // embed message sent by the bot every time.
+                if (messages.size() > 1) {
+                    archiveDynamicVoiceChannel(channelLeft);
+                } else {
+                    channelLeft.delete().queue();
+                }
+            });
         }
     }
 
@@ -82,20 +109,40 @@ private void moveMember(Guild guild, Member member, AudioChannel channel) {
                             member.getNickname(), channel.getName(), error));
     }
 
-    private void deleteDynamicVoiceChannel(AudioChannelUnion channel) {
+    private void archiveDynamicVoiceChannel(AudioChannelUnion channel) {
         int memberCount = channel.getMembers().size();
+        String channelName = channel.getName();
 
         if (memberCount > 0) {
-            logger.debug("Voice channel {} not empty ({} members), so not removing.",
-                    channel.getName(), memberCount);
+            logger.debug("Voice channel {} not empty ({} members), so not removing.", channelName,
+                    memberCount);
+            return;
+        }
+
+        Optional<Category> archiveCategoryOptional = channel.getGuild()
+            .getCategoryCache()
+            .stream()
+            .filter(c -> c.getName().equalsIgnoreCase(ARCHIVE_CATEGORY_NAME))
+            .findFirst();
+
+        AudioChannelManager<?, ?> channelManager = channel.getManager();
+        RestAction<Void> restActionChain =
+                channelManager.setName(String.format("%s (Archived)", channelName))
+                    .and(channel.getPermissionContainer().getManager().clearOverridesAdded());
+
+        if (archiveCategoryOptional.isEmpty()) {
+            logger.warn("Could not find archive category. Attempting to create one...");
+            channel.getGuild()
+                .createCategory(ARCHIVE_CATEGORY_NAME)
+                .queue(newCategory -> restActionChain.and(channelManager.setParent(newCategory))
+                    .queue());
             return;
         }
 
-        channel.delete()
-            .queue(_ -> logger.trace("Deleted dynamically created voice channel: {} ",
-                    channel.getName()),
-                    error -> logger.error("Failed to delete dynamically created voice channel: {} ",
-                            channel.getName(), error));
+        archiveCategoryOptional.ifPresent(archiveCategory -> restActionChain
+            .and(channelManager.setParent(archiveCategory))
+            .queue(_ -> voiceChatCleanupStrategy.cleanup(archiveCategory.getVoiceChannels()),
+                    err -> logger.error("Could not archive dynamic voice chat", err)));
     }
 
     private void sendWarningEmbed(VoiceChannel channel) {

application/src/main/java/org/togetherjava/tjbot/features/voicechat/OldestVoiceChatCleanup.java

@@ -0,0 +1,40 @@
+package org.togetherjava.tjbot.features.voicechat;
+
+import net.dv8tion.jda.api.entities.ISnowflake;
+import net.dv8tion.jda.api.entities.channel.concrete.VoiceChannel;
+
+import java.util.Comparator;
+import java.util.List;
+
+/**
+ * Cleans up voice chats from an archive prioritizing the oldest {@link VoiceChannel}.
+ * <p>
+ * Considering a list of voice channels is provided with all of them obviously having a different
+ * addition time, the first few {@link VoiceChannel} elements provided, amounting to the value of
+ * <code>cleanChannelsAmount</code> will be removed from the guild.
+ * <p>
+ * The cleanup strategy will <i>not</i> be executed if the amount of voice channels does not exceed
+ * the value of <code>minimumChannelsAmountToTrigger</code>.
+ */
+final class OldestVoiceChatCleanup implements VoiceChatCleanupStrategy {
+
+    private final int cleanChannelsAmount;
+    private final int minimumChannelsAmountToTrigger;
+
+    OldestVoiceChatCleanup(int cleanChannelsAmount, int minimumChannelsAmountToTrigger) {
+        this.cleanChannelsAmount = cleanChannelsAmount;
+        this.minimumChannelsAmountToTrigger = minimumChannelsAmountToTrigger;
+    }
+
+    @Override
+    public void cleanup(List<VoiceChannel> voiceChannels) {
+        if (voiceChannels.size() < minimumChannelsAmountToTrigger) {
+            return;
+        }
+
+        voiceChannels.stream()
+            .sorted(Comparator.comparing(ISnowflake::getTimeCreated))
+            .limit(cleanChannelsAmount)
+            .forEach(voiceChannel -> voiceChannel.delete().queue());
+    }
+}

application/src/main/java/org/togetherjava/tjbot/features/voicechat/VoiceChatCleanupStrategy.java

@@ -0,0 +1,21 @@
+package org.togetherjava.tjbot.features.voicechat;
+
+import net.dv8tion.jda.api.entities.channel.concrete.VoiceChannel;
+
+import java.util.List;
+
+/**
+ * Voice chat cleanup strategy interface for handling voice chat archive removal.
+ * <p>
+ * See provided implementation {@link OldestVoiceChatCleanup} for a more concrete usage example.
+ */
+public interface VoiceChatCleanupStrategy {
+
+    /**
+     * Attempts to delete the {@link VoiceChannel} channels from the Discord guild found in the
+     * inputted list.
+     *
+     * @param voiceChannels a list of voice channels to be considered for removal
+     */
+    void cleanup(List<VoiceChannel> voiceChannels);
+}