Implement text display leaderboard

Author: booky10

src/main/java/dev/booky/craftattack/CaMain.java

@@ -5,6 +5,7 @@
 import dev.booky.craftattack.listener.DimensionListener;
 import dev.booky.craftattack.listener.ElytraListener;
 import dev.booky.craftattack.listener.ExplosionListener;
+import dev.booky.craftattack.listener.LeaderboardListener;
 import dev.booky.craftattack.listener.MineStatListener;
 import dev.booky.craftattack.listener.SitListener;
 import dev.booky.craftattack.listener.SpawnListener;
@@ -49,6 +50,7 @@ public void onEnable() {
         Bukkit.getPluginManager().registerEvents(new SpawnListener(this.manager), this);
         Bukkit.getPluginManager().registerEvents(new TeleportListener(this.manager), this);
         Bukkit.getPluginManager().registerEvents(new WarpPlateListener(this.manager), this);
+        Bukkit.getPluginManager().registerEvents(new LeaderboardListener(this.manager), this);
 
         Bukkit.getServicesManager().register(CaManager.class, this.manager, this, ServicePriority.Normal);
 
@@ -57,10 +59,6 @@ public void onEnable() {
 
     @Override
     public void onDisable() {
-        if (this.manager != null) {
-            this.manager.saveConfig();
-        }
-
         if (this.i18n != null) {
             this.i18n.unload();
         }

src/main/java/dev/booky/craftattack/CaManager.java

@@ -4,6 +4,7 @@
 import dev.booky.cloudcore.config.ConfigurateLoader;
 import dev.booky.cloudcore.util.BlockBBox;
 import dev.booky.craftattack.utils.CaConfig;
+import dev.booky.craftattack.utils.LeaderboardTasks;
 import dev.booky.craftattack.utils.TpResult;
 import io.papermc.paper.entity.TeleportFlag;
 import net.kyori.adventure.text.Component;
@@ -47,6 +48,7 @@ public final class CaManager {
     private final NamespacedKey elytraDataKey;
     private final NamespacedKey elytraBoostsKey;
 
+    private final LeaderboardTasks leaderboardTasks = new LeaderboardTasks(this);
     private final Map<UUID, CompletableFuture<TpResult>> teleports = new HashMap<>();
     private final Plugin plugin;
 
@@ -154,6 +156,7 @@ public void updateConfig(Consumer<CaConfig> updater) {
 
     public void reloadConfig() {
         this.config = CONFIG_LOADER.loadObject(this.configPath, CaConfig.class, CaConfig::new);
+        this.leaderboardTasks.handleReload();
     }
 
     public void saveConfig() {
@@ -230,6 +233,10 @@ public OptionalInt consumeElytraBoost(PersistentDataHolder holder) {
         return OptionalInt.empty();
     }
 
+    public LeaderboardTasks getLeaderboardTasks() {
+        return this.leaderboardTasks;
+    }
+
     public CaConfig getConfig() {
         return Objects.requireNonNull(this.config, "Config has not been loaded yet");
     }

src/main/java/dev/booky/craftattack/listener/LeaderboardListener.java

@@ -0,0 +1,33 @@
+package dev.booky.craftattack.listener;
+// Created by booky10 in CraftAttack (03:46 26.10.2025)
+
+import com.destroystokyo.paper.event.entity.EntityAddToWorldEvent;
+import dev.booky.craftattack.CaManager;
+import dev.booky.craftattack.utils.CaConfig;
+import dev.booky.craftattack.utils.LeaderboardTasks;
+import org.bukkit.entity.TextDisplay;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.jspecify.annotations.NullMarked;
+
+@NullMarked
+public class LeaderboardListener implements Listener {
+
+    private final CaManager manager;
+
+    public LeaderboardListener(CaManager manager) {
+        this.manager = manager;
+    }
+
+    @EventHandler
+    public void onEntityAdd(EntityAddToWorldEvent event) {
+        if (!(event.getEntity() instanceof TextDisplay display)) {
+            return; // not a text display
+        }
+        LeaderboardTasks tasks = this.manager.getLeaderboardTasks();
+        CaConfig.LeaderboardConfig config = tasks.getConfig(display.getUniqueId());
+        if (config != null) {
+            tasks.launchUpdater(display, config);
+        }
+    }
+}

src/main/java/dev/booky/craftattack/utils/CaConfig.java

@@ -4,18 +4,21 @@
 import dev.booky.cloudcore.util.BlockBBox;
 import io.papermc.paper.math.BlockPosition;
 import net.kyori.adventure.key.Key;
+import net.kyori.adventure.text.Component;
 import org.bukkit.Location;
 import org.bukkit.Material;
 import org.bukkit.NamespacedKey;
 import org.bukkit.block.Block;
 import org.jspecify.annotations.Nullable;
 import org.spongepowered.configurate.objectmapping.ConfigSerializable;
 
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.UUID;
 
 // Can't be final because of object mapping
 @SuppressWarnings("FieldMayBeFinal")
@@ -166,6 +169,37 @@ public boolean isPreventAbuse() {
 
     private Map<BlockPosition, String> warpPlates = new HashMap<>();
 
+    private List<LeaderboardConfig> leaderboards = new ArrayList<>();
+
+    @ConfigSerializable
+    public static final class LeaderboardConfig {
+
+        private String objective;
+        private UUID entityId;
+        private int entries = 10;
+        private Component wrapper = Component.text("");
+
+        public String getObjective() {
+            return this.objective;
+        }
+
+        public UUID getEntityId() {
+            return this.entityId;
+        }
+
+        public int getEntries() {
+            return this.entries;
+        }
+
+        public Component getWrapper() {
+            return this.wrapper;
+        }
+    }
+
+    public List<LeaderboardConfig> getLeaderboards() {
+        return this.leaderboards;
+    }
+
     public @Nullable String getWarpPlateTarget(BlockPosition pos) {
         return this.warpPlates.get(pos);
     }

src/main/java/dev/booky/craftattack/utils/LeaderboardTask.java

@@ -0,0 +1,35 @@
+package dev.booky.craftattack.utils;
+// Created by booky10 in CraftAttack (02:47 26.10.2025)
+
+import org.bukkit.Bukkit;
+import org.bukkit.entity.TextDisplay;
+import org.jspecify.annotations.NullMarked;
+
+import java.lang.ref.WeakReference;
+
+@NullMarked
+public final class LeaderboardTask implements Runnable {
+
+    private final CaConfig.LeaderboardConfig config;
+    private final WeakReference<TextDisplay> display;
+    private int taskId;
+
+    public LeaderboardTask(CaConfig.LeaderboardConfig config, WeakReference<TextDisplay> display) {
+        this.config = config;
+        this.display = display;
+    }
+
+    @Override
+    public void run() {
+        TextDisplay display = this.display.get();
+        if (display == null || !display.isValid()) {
+            Bukkit.getScheduler().cancelTask(this.taskId); // entity has been removed
+        } else if (!Bukkit.getOnlinePlayers().isEmpty()) {
+            LeaderboardUtil.applyLeaderboard(display, this.config);
+        }
+    }
+
+    public void setTaskId(int taskId) {
+        this.taskId = taskId;
+    }
+}

src/main/java/dev/booky/craftattack/utils/LeaderboardTasks.java

@@ -0,0 +1,60 @@
+package dev.booky.craftattack.utils;
+// Created by booky10 in CraftAttack (03:17 26.10.2025)
+
+import dev.booky.craftattack.CaManager;
+import dev.booky.craftattack.utils.CaConfig.LeaderboardConfig;
+import net.kyori.adventure.util.Ticks;
+import org.bukkit.Bukkit;
+import org.bukkit.entity.TextDisplay;
+import org.bukkit.scheduler.BukkitTask;
+import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
+
+import java.lang.ref.WeakReference;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.UUID;
+
+@NullMarked
+public class LeaderboardTasks {
+
+    private static final long UPDATE_INTERVAL = Ticks.TICKS_PER_SECOND * 42;
+
+    private final CaManager manager;
+
+    private final List<Integer> taskIds = new ArrayList<>();
+    private final Map<UUID, LeaderboardConfig> configs = new HashMap<>();
+
+    public LeaderboardTasks(CaManager manager) {
+        this.manager = manager;
+    }
+
+    public void handleReload() {
+        for (int taskId : this.taskIds) {
+            Bukkit.getScheduler().cancelTask(taskId);
+        }
+        this.taskIds.clear();
+
+        this.configs.clear();
+        for (LeaderboardConfig config : this.manager.getConfig().getLeaderboards()) {
+            this.configs.put(config.getEntityId(), config);
+            if (Bukkit.getEntity(config.getEntityId()) instanceof TextDisplay display) {
+                this.launchUpdater(display, config);
+            }
+        }
+    }
+
+    public void launchUpdater(TextDisplay display, LeaderboardConfig config) {
+        LeaderboardTask lbTask = new LeaderboardTask(config, new WeakReference<>(display));
+        BukkitTask task = Bukkit.getScheduler().runTaskTimer(this.manager.getPlugin(), lbTask, 0L, UPDATE_INTERVAL);
+        // save task id for cancelling later
+        lbTask.setTaskId(task.getTaskId());
+        this.taskIds.add(task.getTaskId());
+    }
+
+    public @Nullable LeaderboardConfig getConfig(UUID entityId) {
+        return this.configs.get(entityId);
+    }
+}

src/main/java/dev/booky/craftattack/utils/LeaderboardUtil.java

@@ -2,9 +2,12 @@
 // Created by booky10 in CraftAttack (02:58 26.10.2025)
 
 import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.TextComponent;
 import net.kyori.adventure.text.format.NamedTextColor;
 import net.minecraft.world.scores.PlayerScoreEntry;
+import org.bukkit.Bukkit;
 import org.bukkit.craftbukkit.scoreboard.CraftScoreboard;
+import org.bukkit.entity.TextDisplay;
 import org.bukkit.scoreboard.Objective;
 import org.bukkit.scoreboard.Scoreboard;
 import org.bukkit.util.NumberConversions;
@@ -43,6 +46,28 @@ private static LeaderboardEntry calcPlacedEntry(UnplacedLeaderboardEntry entry,
         return entry.withPlacement(placement);
     }
 
+    public static void applyLeaderboard(TextDisplay display, CaConfig.LeaderboardConfig config) {
+        LeaderboardResult leaderboard = buildLeaderboard(config);
+        if (leaderboard == null) {
+            return; // objective can't be found
+        }
+        TextComponent.Builder builder = text();
+        for (LeaderboardEntry line : leaderboard.entries()) {
+            Component wrappedComp = config.getWrapper().append(line.buildLine());
+            builder.append(wrappedComp).appendNewline();
+        }
+        display.text(builder.build());
+    }
+
+    public static @Nullable LeaderboardResult buildLeaderboard(CaConfig.LeaderboardConfig config) {
+        Scoreboard scoreboard = Bukkit.getScoreboardManager().getMainScoreboard();
+        Objective objective = scoreboard.getObjective(config.getObjective());
+        if (objective != null) {
+            return buildLeaderboard(objective, config.getEntries(), null);
+        }
+        return null;
+    }
+
     public static LeaderboardResult buildLeaderboard(Objective objective, int size, @Nullable String self) {
         Scoreboard scoreboard = objective.getScoreboard();
         if (scoreboard == null) {