MessageReceivers now subscribe to channels by name patterns

Author: Zabuzard

application/src/main/java/org/togetherjava/tjbot/commands/MessageReceiver.java

@@ -4,18 +4,33 @@
 import net.dv8tion.jda.api.events.message.guild.GuildMessageUpdateEvent;
 import org.jetbrains.annotations.NotNull;
 
+import java.util.regex.Pattern;
+
 /**
- * Receives incoming Discord guild messages.
+ * Receives incoming Discord guild messages from channels matching a given pattern.
  * <p>
  * All message receivers have to implement this interface. For convenience, there is a
  * {@link MessageReceiverAdapter} available that implemented most methods already. A new receiver
  * can then be registered by adding it to {@link Features}.
  * <p>
  * <p>
  * After registration, the system will notify a receiver whenever a new message was sent or an
- * existing message was updated in any of the guilds the bot is added to.
+ * existing message was updated in any channel matching the {@link #getChannelNamePattern()} the bot
+ * is added to.
  */
 public interface MessageReceiver extends Feature {
+    /**
+     * Retrieves the pattern matching the names of channels of which this receiver is interested in
+     * receiving sent messages from. Called by the core system once during the startup in order to
+     * register the receiver accordingly.
+     * <p>
+     * Changes on the pattern returned by this method afterwards will not be picked up.
+     *
+     * @return the pattern matching the names of relevant channels
+     */
+    @NotNull
+    Pattern getChannelNamePattern();
+
     /**
      * Triggered by the core system whenever a new message was sent and received in a text channel
      * of a guild the bot has been added to.

application/src/main/java/org/togetherjava/tjbot/commands/MessageReceiverAdapter.java

@@ -4,6 +4,8 @@
 import net.dv8tion.jda.api.events.message.guild.GuildMessageUpdateEvent;
 import org.jetbrains.annotations.NotNull;
 
+import java.util.regex.Pattern;
+
 /**
  * Adapter implementation of a {@link MessageReceiver}. A new receiver can then be registered by
  * adding it to {@link Features}.
@@ -14,6 +16,23 @@
  */
 public abstract class MessageReceiverAdapter implements MessageReceiver {
 
+    private final Pattern channelNamePattern;
+
+    /**
+     * Creates an instance of a message receiver with the given pattern.
+     *
+     * @param channelNamePattern the pattern matching names of channels interested in, only messages
+     *        from matching channels will be received
+     */
+    protected MessageReceiverAdapter(@NotNull Pattern channelNamePattern) {
+        this.channelNamePattern = channelNamePattern;
+    }
+
+    @Override
+    public final @NotNull Pattern getChannelNamePattern() {
+        return channelNamePattern;
+    }
+
     @SuppressWarnings("NoopMethodInAbstractClass")
     @Override
     public void onMessageReceived(@NotNull GuildMessageReceivedEvent event) {

application/src/main/java/org/togetherjava/tjbot/commands/system/BotCore.java

@@ -2,17 +2,16 @@
 
 import net.dv8tion.jda.api.JDA;
 import net.dv8tion.jda.api.Permission;
+import net.dv8tion.jda.api.entities.AbstractChannel;
 import net.dv8tion.jda.api.entities.Guild;
 import net.dv8tion.jda.api.entities.TextChannel;
-import net.dv8tion.jda.api.events.GenericEvent;
 import net.dv8tion.jda.api.events.ReadyEvent;
 import net.dv8tion.jda.api.events.interaction.ButtonClickEvent;
 import net.dv8tion.jda.api.events.interaction.SelectionMenuEvent;
 import net.dv8tion.jda.api.events.interaction.SlashCommandEvent;
 import net.dv8tion.jda.api.events.message.guild.GuildMessageReceivedEvent;
 import net.dv8tion.jda.api.events.message.guild.GuildMessageUpdateEvent;
 import net.dv8tion.jda.api.exceptions.ErrorHandler;
-import net.dv8tion.jda.api.hooks.EventListener;
 import net.dv8tion.jda.api.hooks.ListenerAdapter;
 import net.dv8tion.jda.api.interactions.commands.Command;
 import net.dv8tion.jda.api.interactions.components.ComponentInteraction;
@@ -32,7 +31,9 @@
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.function.Function;
+import java.util.regex.Pattern;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 /**
  * The bot core is the core of command handling in this application.
@@ -53,6 +54,7 @@ public final class BotCore extends ListenerAdapter implements SlashCommandProvid
     private final Map<String, SlashCommand> nameToSlashCommands;
     private final ComponentIdParser componentIdParser;
     private final ComponentIdStore componentIdStore;
+    private final Map<Pattern, MessageReceiver> channelNameToMessageReceiver = new HashMap<>();
 
     /**
      * Creates a new command system which uses the given database to allow commands to persist data.
@@ -70,8 +72,8 @@ public BotCore(@NotNull JDA jda, @NotNull Database database) {
         features.stream()
             .filter(MessageReceiver.class::isInstance)
             .map(MessageReceiver.class::cast)
-            .map(MessageReceiverAsEventListener::new)
-            .forEach(jda::addEventListener);
+            .forEach(messageReceiver -> channelNameToMessageReceiver
+                .put(messageReceiver.getChannelNamePattern(), messageReceiver));
 
         // Event receivers
         features.stream()
@@ -129,6 +131,29 @@ public void onReady(@NotNull ReadyEvent event) {
         logger.debug("Bot core is now ready");
     }
 
+    @Override
+    public void onGuildMessageReceived(@NotNull GuildMessageReceivedEvent event) {
+        getMessageReceiversSubscribedTo(event.getChannel())
+            .forEach(messageReceiver -> messageReceiver.onMessageReceived(event));
+    }
+
+    @Override
+    public void onGuildMessageUpdate(@NotNull GuildMessageUpdateEvent event) {
+        getMessageReceiversSubscribedTo(event.getChannel())
+            .forEach(messageReceiver -> messageReceiver.onMessageUpdated(event));
+    }
+
+    private @NotNull Stream<MessageReceiver> getMessageReceiversSubscribedTo(
+            @NotNull AbstractChannel channel) {
+        String channelName = channel.getName();
+        return channelNameToMessageReceiver.entrySet()
+            .stream()
+            .filter(patternAndReceiver -> patternAndReceiver.getKey()
+                .matcher(channelName)
+                .matches())
+            .map(Map.Entry::getValue);
+    }
+
     @Override
     public void onSlashCommand(@NotNull SlashCommandEvent event) {
         logger.debug("Received slash command '{}' (#{}) on guild '{}'", event.getName(),
@@ -283,25 +308,4 @@ private interface TriConsumer<A, B, C> {
          */
         void accept(A first, B second, C third);
     }
-
-    private static final class MessageReceiverAsEventListener implements EventListener {
-        private final MessageReceiver messageReceiver;
-
-        MessageReceiverAsEventListener(MessageReceiver messageReceiver) {
-            this.messageReceiver = messageReceiver;
-        }
-
-        @SuppressWarnings("squid:S2583") // False-positive about the if-else-instanceof, sonar
-                                         // thinks the second case is unreachable; but it passes
-                                         // without pattern-matching. Probably a bug in SonarLint
-                                         // with Java 17.
-        @Override
-        public void onEvent(@NotNull GenericEvent event) {
-            if (event instanceof GuildMessageReceivedEvent receivedEvent) {
-                messageReceiver.onMessageReceived(receivedEvent);
-            } else if (event instanceof GuildMessageUpdateEvent updateEvent) {
-                messageReceiver.onMessageUpdated(updateEvent);
-            }
-        }
-    }
 }