Feature/leaderboard command

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

@@ -38,6 +38,7 @@
 import org.togetherjava.tjbot.features.help.PinnedNotificationRemover;
 import org.togetherjava.tjbot.features.jshell.JShellCommand;
 import org.togetherjava.tjbot.features.jshell.JShellEval;
+import org.togetherjava.tjbot.features.leaderboard.LeaderboardCommand;
 import org.togetherjava.tjbot.features.mathcommands.TeXCommand;
 import org.togetherjava.tjbot.features.mathcommands.wolframalpha.WolframAlphaCommand;
 import org.togetherjava.tjbot.features.mediaonly.MediaOnlyChannelListener;
@@ -202,6 +203,7 @@ public static Collection<Feature> createFeatures(JDA jda, Database database, Con
         features.add(new AuditCommand(actionsStore));
         features.add(new MuteCommand(actionsStore, config));
         features.add(new UnmuteCommand(actionsStore, config));
+        features.add(new LeaderboardCommand(config));
         features.add(new TopHelpersCommand(topHelpersService, topHelpersAssignmentRoutine));
         features.add(new RoleSelectCommand());
         features.add(new NoteCommand(actionsStore));

application/src/main/java/org/togetherjava/tjbot/features/leaderboard/LeaderboardCommand.java

@@ -0,0 +1,171 @@
+package org.togetherjava.tjbot.features.leaderboard;
+
+import net.dv8tion.jda.api.EmbedBuilder;
+import net.dv8tion.jda.api.entities.Guild;
+import net.dv8tion.jda.api.entities.Member;
+import net.dv8tion.jda.api.entities.Message;
+import net.dv8tion.jda.api.entities.User;
+import net.dv8tion.jda.api.entities.channel.concrete.TextChannel;
+import net.dv8tion.jda.api.events.interaction.command.SlashCommandInteractionEvent;
+import net.dv8tion.jda.api.interactions.InteractionHook;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.togetherjava.tjbot.config.Config;
+import org.togetherjava.tjbot.features.CommandVisibility;
+import org.togetherjava.tjbot.features.SlashCommandAdapter;
+import org.togetherjava.tjbot.features.tophelper.TopHelpersService;
+import org.togetherjava.tjbot.features.utils.Colors;
+
+import java.time.Instant;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Map;
+import java.util.StringJoiner;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.regex.Pattern;
+
+/**
+ * Implements the {@code /leaderboard} slash command, which displays the all-time top helpers
+ * leaderboard by reading the hall-of-fame channel history.
+ */
+public final class LeaderboardCommand extends SlashCommandAdapter {
+    private static final Logger logger = LoggerFactory.getLogger(LeaderboardCommand.class);
+
+    private static final String COMMAND_NAME = "leaderboard";
+    private static final int TOP_LIMIT = 10;
+    private static final int HISTORY_LIMIT = 500;
+
+    private static final String MEDAL_FIRST = "🥇";
+    private static final String MEDAL_SECOND = "🥈";
+    private static final String MEDAL_THIRD = "🥉";
+    private static final String BULLET = "▸";
+
+    private final Config config;
+
+    private final Map<Long, Map<Long, Integer>> winsByGuild = new ConcurrentHashMap<>();
+    private final Map<Long, Instant> lastFetchedPerGuild = new ConcurrentHashMap<>();
+
+    public LeaderboardCommand(Config config) {
+        super(COMMAND_NAME, "Show the all-time top helpers leaderboard", CommandVisibility.GUILD);
+        this.config = config;
+    }
+
+    @Override
+    public void onSlashCommand(SlashCommandInteractionEvent event) {
+        Guild guild = event.getGuild();
+        if (guild == null) {
+            event.reply("This command can only be used inside a server.")
+                .setEphemeral(true)
+                .queue();
+            return;
+        }
+
+        event.deferReply().queue();
+
+        Pattern channelPattern =
+                Pattern.compile(config.getTopHelpers().getAnnouncementChannelPattern());
+        TextChannel hallOfFame = guild.getTextChannels()
+            .stream()
+            .filter(channel -> channelPattern.matcher(channel.getName()).find())
+            .findFirst()
+            .orElse(null);
+
+        if (hallOfFame == null) {
+            event.getHook().editOriginal("Could not find the hall of fame channel.").queue();
+            return;
+        }
+
+        long guildId = guild.getIdLong();
+        InteractionHook hook = event.getHook();
+
+        Map<Long, Integer> cachedWins =
+                winsByGuild.computeIfAbsent(guildId, _ -> new ConcurrentHashMap<>());
+        Instant lastFetched = lastFetchedPerGuild.get(guildId);
+
+        fetchNewMessages(hallOfFame, lastFetched).thenAccept(newMessages -> {
+            if (!newMessages.isEmpty()) {
+                countWinsInto(newMessages, cachedWins);
+                lastFetchedPerGuild.put(guildId,
+                        newMessages.getFirst().getTimeCreated().toInstant());
+            }
+            sendLeaderboard(guild, cachedWins, hook);
+        }).exceptionally(error -> {
+            logger.error("Failed to read hall of fame channel", error);
+            hook.editOriginal("Failed to read the hall of fame channel.").queue();
+            return null;
+        });
+    }
+
+    private static CompletableFuture<List<Message>> fetchNewMessages(TextChannel channel,
+            Instant lastFetched) {
+        if (lastFetched == null) {
+            return channel.getIterableHistory().takeAsync(HISTORY_LIMIT);
+        }
+        return channel.getIterableHistory()
+            .takeWhileAsync(HISTORY_LIMIT,
+                    msg -> msg.getTimeCreated().toInstant().isAfter(lastFetched));
+    }
+
+    private void sendLeaderboard(Guild guild, Map<Long, Integer> wins, InteractionHook hook) {
+        List<Map.Entry<Long, Integer>> sorted = wins.entrySet()
+            .stream()
+            .sorted(Map.Entry.comparingByValue(Comparator.reverseOrder()))
+            .limit(TOP_LIMIT)
+            .toList();
+
+        if (sorted.isEmpty()) {
+            hook.editOriginal("No top helper data found.").queue();
+            return;
+        }
+
+        List<Long> ids = sorted.stream().map(Map.Entry::getKey).toList();
+
+        guild.retrieveMembersByIds(ids).onSuccess(members -> {
+            Map<Long, Member> memberById = TopHelpersService.mapUserIdToMember(members);
+
+            StringJoiner description = new StringJoiner("\n");
+            for (int i = 0; i < sorted.size(); i++) {
+                Map.Entry<Long, Integer> entry = sorted.get(i);
+                Member member = memberById.get(entry.getKey());
+                String name = TopHelpersService.getUsernameDisplay(member);
+                int winCount = entry.getValue();
+                description.add("%s **%s** — %d month%s".formatted(rankPrefix(i), name, winCount,
+                        winCount == 1 ? "" : "s"));
+            }
+
+            EmbedBuilder embed = new EmbedBuilder().setTitle("🏆 Top Helpers — Hall of Fame")
+                .setDescription(description.toString())
+                .setColor(Colors.SUCCESS_COLOR)
+                .setFooter("Times awarded Top Helper");
+
+            hook.editOriginalEmbeds(embed.build()).queue();
+
+        }).onError(error -> {
+            logger.error("Failed to retrieve members for leaderboard", error);
+            hook.editOriginal("Failed to load member data, please try again.").queue();
+        });
+    }
+
+    private static void countWinsInto(List<Message> messages, Map<Long, Integer> wins) {
+        for (Message message : messages) {
+            String content = message.getContentRaw();
+            if (!content.toLowerCase().contains("top helper")) {
+                continue;
+            }
+            for (User user : message.getMentions().getUsers()) {
+                wins.merge(user.getIdLong(), 1, Integer::sum);
+            }
+        }
+    }
+
+    private static String rankPrefix(int zeroBasedIndex) {
+        return switch (zeroBasedIndex) {
+            case 0 -> MEDAL_FIRST;
+            case 1 -> MEDAL_SECOND;
+            case 2 -> MEDAL_THIRD;
+            default -> BULLET + " #" + (zeroBasedIndex + 1);
+        };
+    }
+}

application/src/main/java/org/togetherjava/tjbot/features/leaderboard/package-info.java

@@ -0,0 +1,4 @@
+@MethodsReturnNonnullByDefault
+package org.togetherjava.tjbot.features.leaderboard;
+
+import org.togetherjava.tjbot.annotations.MethodsReturnNonnullByDefault;