Implement merchant blacklist, blocking any listed characters from entering

src/main/java/net/server/channel/handlers/PlayerInteractionHandler.java

@@ -44,7 +44,6 @@ import tools.PacketCreator;
 import java.awt.*;
 import java.sql.SQLException;
 import java.util.Arrays;
-import java.util.List;
 
 /**
  * @author Matze
@@ -286,8 +285,7 @@ public final class PlayerInteractionHandler extends AbstractPacketHandler {
 
                     int oid = p.readInt();
                     MapObject ob = chr.getMap().getMapObject(oid);
-                    if (ob instanceof PlayerShop) {
-                        PlayerShop shop = (PlayerShop) ob;
+                    if (ob instanceof PlayerShop shop) {
                         shop.visitShop(chr);
                     } else if (ob instanceof MiniGame) {
                         p.skip(1);
@@ -691,10 +689,26 @@ public final class PlayerInteractionHandler extends AbstractPacketHandler {
                 }
                 c.sendPacket(PacketCreator.viewMerchantVisitorHistory(merchant.getVisitorHistory()));
             } else if (mode == Action.VIEW_BLACKLIST.getCode()) {
-                List<String> blacklistedNames = List.of("Blanca", "Betsy", "Kevin", "Rosa", "Evan", "Terence",
-                        "Cecilia", "Gayle", "Erma", "Dorothy", "Willis", "Alberta", "Marilyn", "Myron", "Sheryl",
-                        "Marco", "Jose", "Kendra", "Laurence", "Victoria", "NonListed");
-                c.sendPacket(PacketCreator.viewMerchantBlacklist(blacklistedNames));
+                HiredMerchant merchant = chr.getHiredMerchant();
+                if (merchant == null || !merchant.isOwner(chr)) {
+                    return;
+                }
+
+                c.sendPacket(PacketCreator.viewMerchantBlacklist(merchant.getBlacklist()));
+            } else if (mode == Action.ADD_TO_BLACKLIST.getCode()) {
+                HiredMerchant merchant = chr.getHiredMerchant();
+                if (merchant == null || !merchant.isOwner(chr)) {
+                    return;
+                }
+                String chrName = p.readString();
+                merchant.addToBlacklist(chrName);
+            } else if (mode == Action.REMOVE_FROM_BLACKLIST.getCode()) {
+                HiredMerchant merchant = chr.getHiredMerchant();
+                if (merchant == null || !merchant.isOwner(chr)) {
+                    return;
+                }
+                String chrName = p.readString();
+                merchant.removeFromBlacklist(chrName);
             } else if (mode == Action.MERCHANT_ORGANIZE.getCode()) {
                 HiredMerchant merchant = chr.getHiredMerchant();
                 if (merchant == null || !merchant.isOwner(chr)) {

src/main/java/server/maps/HiredMerchant.java

@@ -47,10 +47,7 @@ import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.time.Duration;
 import java.time.Instant;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.LinkedList;
-import java.util.List;
+import java.util.*;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.locks.Lock;
 
@@ -78,6 +75,7 @@ public class HiredMerchant extends AbstractMapObject {
     private MapleMap map;
     private final Visitor[] visitors = new Visitor[3];
     private final LinkedList<PastVisitor> visitorHistory = new LinkedList<>();
+    private final LinkedHashSet<String> blacklist = new LinkedHashSet<>(); // case-sensitive character names
     private final Lock visitorLock = MonitoredReentrantLockFactory.createLock(MonitoredLockType.VISITOR_MERCH, true);
 
     private record Visitor(Character chr, Instant enteredAt) {}
@@ -489,6 +487,9 @@ public class HiredMerchant extends AbstractMapObject {
             } else if (!this.isOpen()) {
                 chr.sendPacket(PacketCreator.getMiniRoomError(18));
                 return;
+            } else if (isBlacklisted(chr.getName())) {
+                chr.sendPacket(PacketCreator.getMiniRoomError(17));
+                return;
             } else if (!this.addVisitor(chr)) {
                 chr.sendPacket(PacketCreator.getMiniRoomError(2));
                 return;
@@ -722,6 +723,40 @@ public class HiredMerchant extends AbstractMapObject {
         return Collections.unmodifiableList(visitorHistory);
     }
 
+    public void addToBlacklist(String chrName) {
+        visitorLock.lock();
+        try {
+            if (blacklist.size() >= BLACKLIST_LIMIT) {
+                return;
+            }
+            blacklist.add(chrName);
+        } finally {
+            visitorLock.unlock();
+        }
+    }
+
+    public void removeFromBlacklist(String chrName) {
+        visitorLock.lock();
+        try {
+            blacklist.remove(chrName);
+        } finally {
+            visitorLock.unlock();
+        }
+    }
+
+    public Set<String> getBlacklist() {
+        return Collections.unmodifiableSet(blacklist);
+    }
+
+    private boolean isBlacklisted(String chrName) {
+        visitorLock.lock();
+        try {
+            return blacklist.contains(chrName);
+        } finally {
+            visitorLock.unlock();
+        }
+    }
+
     public int getMapId() {
         return map.getId();
     }

src/main/java/tools/PacketCreator.java

@@ -5221,7 +5221,7 @@ public class PacketCreator {
     /**
      * @param chrNames Blacklisted names. The first 20 names will be displayed, anything beyond does no difference.
      */
-    public static Packet viewMerchantBlacklist(List<String> chrNames) {
+    public static Packet viewMerchantBlacklist(Set<String> chrNames) {
         final OutPacket p = OutPacket.create(SendOpcode.PLAYER_INTERACTION);
         p.writeByte(PlayerInteractionHandler.Action.VIEW_BLACKLIST.getCode());
         p.writeShort(chrNames.size());