feat(cool-messages): add primary logic

application/src/main/java/org/togetherjava/tjbot/features/Features.java

@@ -6,6 +6,7 @@
 import org.togetherjava.tjbot.config.FeatureBlacklist;
 import org.togetherjava.tjbot.config.FeatureBlacklistConfig;
 import org.togetherjava.tjbot.db.Database;
+import org.togetherjava.tjbot.features.basic.CoolMessagesBoardManager;
 import org.togetherjava.tjbot.features.basic.MemberCountDisplayRoutine;
 import org.togetherjava.tjbot.features.basic.PingCommand;
 import org.togetherjava.tjbot.features.basic.RoleSelectCommand;
@@ -150,6 +151,7 @@ public static Collection<Feature> createFeatures(JDA jda, Database database, Con
         features.add(new CodeMessageManualDetection(codeMessageHandler));
         features.add(new SlashCommandEducator());
         features.add(new PinnedNotificationRemover(config));
+        features.add(new CoolMessagesBoardManager(config));
 
         // Event receivers
         features.add(new RejoinModerationRoleListener(actionsStore, config));

application/src/main/java/org/togetherjava/tjbot/features/basic/CoolMessagesBoardManager.java

@@ -0,0 +1,141 @@
+package org.togetherjava.tjbot.features.basic;
+
+import net.dv8tion.jda.api.EmbedBuilder;
+import net.dv8tion.jda.api.JDA;
+import net.dv8tion.jda.api.entities.Message;
+import net.dv8tion.jda.api.entities.MessageEmbed;
+import net.dv8tion.jda.api.entities.MessageReaction;
+import net.dv8tion.jda.api.entities.User;
+import net.dv8tion.jda.api.entities.channel.concrete.TextChannel;
+import net.dv8tion.jda.api.entities.emoji.Emoji;
+import net.dv8tion.jda.api.events.message.react.MessageReactionAddEvent;
+import net.dv8tion.jda.api.requests.restaction.MessageCreateAction;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.togetherjava.tjbot.config.Config;
+import org.togetherjava.tjbot.config.CoolMessagesBoardConfig;
+import org.togetherjava.tjbot.features.MessageReceiverAdapter;
+
+import java.awt.Color;
+import java.util.Collections;
+import java.util.Optional;
+import java.util.function.Predicate;
+import java.util.regex.Pattern;
+
+/**
+ * Manager for the cool messages board. It appends highly-voted text messages to a separate channel
+ * where members of the guild can see a list of all of them.
+ */
+public final class CoolMessagesBoardManager extends MessageReceiverAdapter {
+
+    private static final Logger logger = LoggerFactory.getLogger(CoolMessagesBoardManager.class);
+    private Emoji coolEmoji;
+    private final Predicate<String> boardChannelNamePredicate;
+    private final CoolMessagesBoardConfig config;
+
+    public CoolMessagesBoardManager(Config config) {
+        this.config = config.getCoolMessagesConfig();
+        this.coolEmoji = Emoji.fromUnicode(this.config.reactionEmoji());
+
+        boardChannelNamePredicate =
+                Pattern.compile(this.config.boardChannelPattern()).asMatchPredicate();
+    }
+
+    @Override
+    public void onMessageReactionAdd(MessageReactionAddEvent event) {
+        final MessageReaction messageReaction = event.getReaction();
+        int originalReactionsCount = messageReaction.hasCount() ? messageReaction.getCount() : 0;
+        boolean isCoolEmoji = messageReaction.getEmoji().equals(coolEmoji);
+        long guildId = event.getGuild().getIdLong();
+        Optional<TextChannel> boardChannel = getBoardChannel(event.getJDA(), guildId);
+
+        if (boardChannel.isEmpty()) {
+            logger.warn(
+                    "Could not find board channel with pattern '{}' in server with ID '{}'. Skipping reaction handling...",
+                    this.config.boardChannelPattern(), guildId);
+            return;
+        }
+
+        // If the bot has already reacted to this message, then this means that
+        // the message has been quoted to the cool messages board, so skip it.
+        if (hasBotReacted(event.getJDA(), messageReaction)) {
+            return;
+        }
+
+        final int newReactionsCount = originalReactionsCount + 1;
+        if (isCoolEmoji && newReactionsCount >= config.minimumReactions()) {
+            event.retrieveMessage()
+                .queue(message -> message.addReaction(coolEmoji)
+                    .flatMap(v -> insertCoolMessage(boardChannel.get(), message))
+                    .queue(),
+                        e -> logger.warn("Tried to retrieve cool message but got: {}",
+                                e.getMessage()));
+        }
+    }
+
+    /**
+     * Gets the board text channel where the quotes go to, wrapped in an optional.
+     *
+     * @param jda the JDA
+     * @param guildId the guild ID
+     * @return the board text channel
+     */
+    private Optional<TextChannel> getBoardChannel(JDA jda, long guildId) {
+        return jda.getGuildById(guildId)
+            .getTextChannelCache()
+            .stream()
+            .filter(channel -> boardChannelNamePredicate.test(channel.getName()))
+            .findAny();
+    }
+
+    /**
+     * Inserts a message to the specified text channel
+     *
+     * @return a {@link MessageCreateAction} of the call to make
+     */
+    private static MessageCreateAction insertCoolMessage(TextChannel boardChannel,
+            Message message) {
+        return boardChannel.sendMessageEmbeds(Collections.singleton(createQuoteEmbed(message)));
+    }
+
+    /**
+     * Wraps a text message into a properly formatted quote message used for the board text channel.
+     */
+    private static MessageEmbed createQuoteEmbed(Message message) {
+        final User author = message.getAuthor();
+        EmbedBuilder embedBuilder = new EmbedBuilder();
+
+        // If the message contains image(s), include the first one
+        var firstImageAttachment = message.getAttachments()
+            .stream()
+            .parallel()
+            .filter(Message.Attachment::isImage)
+            .findAny()
+            .orElse(null);
+
+        if (firstImageAttachment != null) {
+            embedBuilder.setThumbnail(firstImageAttachment.getUrl());
+        }
+
+        return embedBuilder.setDescription(message.getContentDisplay())
+            .appendDescription("%n%n[Jump to Message](%s)".formatted(message.getJumpUrl()))
+            .setColor(Color.orange)
+            .setAuthor(author.getName(), null, author.getAvatarUrl())
+            .setTimestamp(message.getTimeCreated())
+            .build();
+    }
+
+    /**
+     * Checks a {@link MessageReaction} to see if the bot has reacted to it.
+     */
+    private boolean hasBotReacted(JDA jda, MessageReaction messageReaction) {
+        if (!coolEmoji.equals(messageReaction.getEmoji())) {
+            return false;
+        }
+
+        return messageReaction.retrieveUsers()
+            .parallelStream()
+            .anyMatch(user -> jda.getSelfUser().getIdLong() == user.getIdLong());
+    }
+}