Add optional round-target billboard display

src/main/java/us/tss3/blockparty/arena/Arena.java

@@ -10,6 +10,7 @@ import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.scheduler.BukkitTask;
 import us.tss3.blockparty.BlockPartyPlugin;
+import us.tss3.blockparty.billboard.BillboardManager;
 import us.tss3.blockparty.config.ArenaConfig;
 import us.tss3.blockparty.floor.FloorManager;
 import us.tss3.blockparty.logic.ArenaPhase;
@@ -35,6 +36,7 @@ public class Arena {
     private final BlockPartyPlugin plugin;
     private final ArenaConfig config;
     private final FloorManager floorManager;
+    private final BillboardManager billboardManager;
     private final ArenaStateMachine stateMachine = new ArenaStateMachine(ArenaPhase.DISABLED);
     private final Random random = new Random();
     private final TargetColorSelector selector = new TargetColorSelector(random::nextInt);
@@ -56,6 +58,7 @@ public class Arena {
         this.plugin = plugin;
         this.config = config;
         this.floorManager = new FloorManager(plugin, config);
+        this.billboardManager = new BillboardManager(plugin, config);
         if (config.isEnabled()) {
             stateMachine.transition(ArenaPhase.WAITING);
         }
@@ -109,6 +112,7 @@ public class Arena {
 
     public void disable() {
         cancelAllTasks();
+        billboardManager.despawn();
         // Force reset players out regardless of state
         List<UUID> all = new ArrayList<>();
         all.addAll(players);
@@ -318,6 +322,7 @@ public class Arena {
             p.getInventory().setItem(8, display.clone());
             plugin.getSoundUtil().play(p, plugin.getConfigManager().getSound("target-select"), 1f, 1f);
         }
+        billboardManager.show(currentTarget);
     }
 
     private void setupBossBar() {
@@ -493,6 +498,7 @@ public class Arena {
         floorManager.cancelActiveTask();
         cancelAllTasks();
         round = 0;
+        billboardManager.clear();
         stateMachine.transition(ArenaPhase.WAITING);
     }
 
@@ -516,6 +522,7 @@ public class Arena {
     /** Called on plugin disable / world unload to safely stop everything and restore players. */
     public void shutdown() {
         cancelAllTasks();
+        billboardManager.despawn();
         List<UUID> all = allParticipants();
         for (UUID uuid : all) {
             Player p = plugin.getServer().getPlayer(uuid);
@@ -529,6 +536,10 @@ public class Arena {
         spectators.clear();
     }
 
+    public BillboardManager getBillboardManager() {
+        return billboardManager;
+    }
+
     private String formatMaterial(Material material) {
         String name = material.name().replace("_CONCRETE", "").replace("_", " ").toLowerCase();
         return name.substring(0, 1).toUpperCase() + name.substring(1);

src/main/java/us/tss3/blockparty/billboard/BillboardManager.java

@@ -0,0 +1,109 @@
+package us.tss3.blockparty.billboard;
+
+import org.bukkit.Location;
+import org.bukkit.Material;
+import org.bukkit.entity.BlockDisplay;
+import org.bukkit.entity.Entity;
+import org.bukkit.util.Transformation;
+import org.joml.AxisAngle4f;
+import org.joml.Vector3f;
+import us.tss3.blockparty.BlockPartyPlugin;
+import us.tss3.blockparty.config.ArenaConfig;
+
+import java.util.UUID;
+import java.util.logging.Level;
+
+/**
+ * Owns an optional {@link BlockDisplay} entity that visually mirrors an arena's currently
+ * selected target color. Purely cosmetic: fully optional (global toggle + per-arena
+ * toggle/location), and every method safely no-ops when disabled, unset, or the arena's
+ * world isn't loaded.
+ */
+public class BillboardManager {
+
+    private static final AxisAngle4f NO_ROTATION = new AxisAngle4f(0f, 0f, 0f, 1f);
+
+    private final BlockPartyPlugin plugin;
+    private final ArenaConfig config;
+    private UUID entityId;
+
+    public BillboardManager(BlockPartyPlugin plugin, ArenaConfig config) {
+        this.plugin = plugin;
+        this.config = config;
+    }
+
+    private boolean isActive() {
+        return plugin.getConfigManager().isBillboardEnabled() && config.hasBillboard()
+                && config.getBillboard().getWorld() != null;
+    }
+
+    /** Shows (spawning the display entity if needed) the given material as the current target. */
+    public void show(Material material) {
+        if (!isActive()) {
+            return;
+        }
+        try {
+            BlockDisplay display = resolve();
+            if (display == null) {
+                display = spawn();
+            }
+            if (display != null) {
+                display.setBlock(material.createBlockData());
+            }
+        } catch (Exception ex) {
+            plugin.getLogger().log(Level.WARNING, "Failed to update billboard for arena '" + config.getName() + "'", ex);
+        }
+    }
+
+    /** Blanks the display (e.g. between matches) without destroying the entity. */
+    public void clear() {
+        BlockDisplay display = resolve();
+        if (display != null) {
+            display.setBlock(Material.AIR.createBlockData());
+        }
+    }
+
+    /** Fully removes the display entity. Safe to call even if nothing was ever spawned. */
+    public void despawn() {
+        BlockDisplay display = resolve();
+        if (display != null) {
+            display.remove();
+        }
+        entityId = null;
+    }
+
+    /** Forces the entity to be re-created at its (possibly updated) configured location next time it's shown. */
+    public void invalidate() {
+        despawn();
+    }
+
+    private BlockDisplay resolve() {
+        if (entityId == null) {
+            return null;
+        }
+        Entity entity = plugin.getServer().getEntity(entityId);
+        if (entity instanceof BlockDisplay display && !display.isDead()) {
+            return display;
+        }
+        entityId = null;
+        return null;
+    }
+
+    private BlockDisplay spawn() {
+        Location loc = config.getBillboard();
+        if (loc == null || loc.getWorld() == null) {
+            return null;
+        }
+        BlockDisplay display = loc.getWorld().spawn(loc, BlockDisplay.class, bd -> {
+            bd.setPersistent(false);
+            bd.setGlowing(true);
+            bd.setTransformation(new Transformation(
+                    new Vector3f(-0.75f, 0f, -0.75f),
+                    NO_ROTATION,
+                    new Vector3f(1.5f, 1.5f, 1.5f),
+                    NO_ROTATION));
+        });
+        entityId = display.getUniqueId();
+        return display;
+    }
+}

src/main/java/us/tss3/blockparty/command/BlockPartyCommand.java

@@ -45,6 +45,8 @@ public class BlockPartyCommand implements CommandExecutor, TabCompleter {
             case "setlobby" -> setLobby(sender, args);
             case "setspawn" -> setSpawn(sender, args);
             case "setspectator" -> setSpectator(sender, args);
+            case "setbillboard" -> setBillboard(sender, args);
+            case "delbillboard" -> delBillboard(sender, args);
             case "pos1" -> pos1(sender, args);
             case "pos2" -> pos2(sender, args);
             case "setfloor" -> setFloor(sender, args);
@@ -75,6 +77,8 @@ public class BlockPartyCommand implements CommandExecutor, TabCompleter {
                 "/blockparty setlobby <arena>",
                 "/blockparty setspawn <arena>",
                 "/blockparty setspectator <arena>",
+                "/blockparty setbillboard <arena>",
+                "/blockparty delbillboard <arena>",
                 "/blockparty pos1 <arena>",
                 "/blockparty pos2 <arena>",
                 "/blockparty setfloor <arena>",
@@ -191,6 +195,27 @@ public class BlockPartyCommand implements CommandExecutor, TabCompleter {
         });
     }
 
+    private void setBillboard(CommandSender sender, String[] args) {
+        if (!requireAdmin(sender, "blockparty.admin.setup") || !requirePlayer(sender)) return;
+        withArena(sender, args, arena -> {
+            arena.getConfig().setBillboard(((Player) sender).getLocation());
+            arena.getConfig().setBillboardEnabled(true);
+            arena.getBillboardManager().invalidate();
+            plugin.getArenaManager().save(arena);
+            sender.sendMessage(plugin.getMessages().get("admin.billboard-set", Map.of("arena", arena.getConfig().getName())));
+        });
+    }
+
+    private void delBillboard(CommandSender sender, String[] args) {
+        if (!requireAdmin(sender, "blockparty.admin.setup")) return;
+        withArena(sender, args, arena -> {
+            arena.getBillboardManager().despawn();
+            arena.getConfig().setBillboard(null);
+            plugin.getArenaManager().save(arena);
+            sender.sendMessage(plugin.getMessages().get("admin.billboard-removed", Map.of("arena", arena.getConfig().getName())));
+        });
+    }
+
     private void pos1(CommandSender sender, String[] args) {
         if (!requireAdmin(sender, "blockparty.admin.setup") || !requirePlayer(sender)) return;
         withArena(sender, args, arena -> {
@@ -277,6 +302,7 @@ public class BlockPartyCommand implements CommandExecutor, TabCompleter {
         sender.sendMessage("§7Lobby set: §f" + (cfg.getLobby() != null));
         sender.sendMessage("§7Spawn set: §f" + (cfg.getSpawn() != null));
         sender.sendMessage("§7Spectator set: §f" + (cfg.getSpectator() != null));
+        sender.sendMessage("§7Billboard set: §f" + (cfg.getBillboard() != null) + (cfg.getBillboard() != null ? " (enabled: " + cfg.isBillboardEnabled() + ")" : ""));
         sender.sendMessage("§7Floor region set: §f" + cfg.hasFloorRegion());
         sender.sendMessage("§7Floor generated: §f" + cfg.hasGeneratedLayout());
         sender.sendMessage("§7Floor materials: §f" + cfg.getFloorMaterials().size());
@@ -394,7 +420,7 @@ public class BlockPartyCommand implements CommandExecutor, TabCompleter {
     public List<String> onTabComplete(CommandSender sender, Command command, String alias, String[] args) {
         if (args.length == 1) {
             return List.of("help", "join", "leave", "arenas", "stats", "create", "delete", "enable", "disable",
-                            "setlobby", "setspawn", "setspectator", "pos1", "pos2", "setfloor", "generate", "info", "list", "reload")
+                            "setlobby", "setspawn", "setspectator", "setbillboard", "delbillboard", "pos1", "pos2", "setfloor", "generate", "info", "list", "reload")
                     .stream().filter(s -> s.startsWith(args[0].toLowerCase())).collect(Collectors.toList());
         }
         if (args.length == 2) {

src/main/java/us/tss3/blockparty/config/ArenaConfig.java

@@ -15,6 +15,8 @@ public class ArenaConfig {
     private Location lobby;
     private Location spawn;
     private Location spectator;
+    private Location billboard;
+    private boolean billboardEnabled = true;
     private int[] pos1; // x,y,z block coords
     private int[] pos2;
 
@@ -84,6 +86,26 @@ public class ArenaConfig {
         this.spectator = spectator;
     }
 
+    public Location getBillboard() {
+        return billboard;
+    }
+
+    public void setBillboard(Location billboard) {
+        this.billboard = billboard;
+    }
+
+    public boolean isBillboardEnabled() {
+        return billboardEnabled;
+    }
+
+    public void setBillboardEnabled(boolean billboardEnabled) {
+        this.billboardEnabled = billboardEnabled;
+    }
+
+    public boolean hasBillboard() {
+        return billboard != null && billboardEnabled;
+    }
+
     public int[] getPos1() {
         return pos1;
     }

src/main/java/us/tss3/blockparty/config/ArenaConfigLoader.java

@@ -57,6 +57,8 @@ public class ArenaConfigLoader {
         cfg.setLobby(LocationUtil.fromSection(yml.getConfigurationSection("lobby")));
         cfg.setSpawn(LocationUtil.fromSection(yml.getConfigurationSection("spawn")));
         cfg.setSpectator(LocationUtil.fromSection(yml.getConfigurationSection("spectator")));
+        cfg.setBillboard(LocationUtil.fromSection(yml.getConfigurationSection("billboard")));
+        cfg.setBillboardEnabled(yml.getBoolean("billboard-enabled", true));
         if (yml.contains("pos1")) {
             cfg.setPos1(new int[]{yml.getInt("pos1.x"), yml.getInt("pos1.y"), yml.getInt("pos1.z")});
         }
@@ -106,6 +108,10 @@ public class ArenaConfigLoader {
         if (cfg.getSpectator() != null) {
             LocationUtil.toSection(yml.createSection("spectator"), cfg.getSpectator());
         }
+        if (cfg.getBillboard() != null) {
+            LocationUtil.toSection(yml.createSection("billboard"), cfg.getBillboard());
+        }
+        yml.set("billboard-enabled", cfg.isBillboardEnabled());
         if (cfg.getPos1() != null) {
             yml.set("pos1.x", cfg.getPos1()[0]);
             yml.set("pos1.y", cfg.getPos1()[1]);

src/main/java/us/tss3/blockparty/config/ConfigManager.java

@@ -33,6 +33,10 @@ public class ConfigManager {
         return config.getBoolean("ui.bossbar", true);
     }
 
+    public boolean isBillboardEnabled() {
+        return config.getBoolean("ui.billboard", true);
+    }
+
     public boolean isTitlesEnabled() {
         return config.getBoolean("ui.titles", true);
     }