override team rules to always hide the player name when njn is present

src/main/java/me/youhavetrouble/notjustnameplates/nameplates/NameplateManager.java

@@ -2,6 +2,7 @@ package me.youhavetrouble.notjustnameplates.nameplates;
 
 import me.youhavetrouble.notjustnameplates.NotJustNameplates;
 import me.youhavetrouble.notjustnameplates.displays.DisplayContent;
+import me.youhavetrouble.notjustnameplates.packets.TeamPacketListener;
 import net.minecraft.world.phys.AABB;
 import org.bukkit.*;
 import org.bukkit.block.Block;
@@ -40,6 +41,7 @@ public class NameplateManager implements Listener {
 
     @EventHandler(ignoreCancelled = true, priority = EventPriority.HIGHEST)
     public void onPlayerJoin(PlayerJoinEvent event) {
+        TeamPacketListener.addPlayer(event.getPlayer());
         UUID joinerUuid = event.getPlayer().getUniqueId();
         DisplayContent displayContent = NotJustNameplates.getInstance().getDisplayContentForPlayerBasedOnPermission(event.getPlayer());
         if (displayContent == null) return;
@@ -102,6 +104,11 @@ public class NameplateManager implements Listener {
         event.setShouldRetry(true);
     }
 
+    @EventHandler
+    public void onPlayerQuit(PlayerQuitEvent event) {
+        TeamPacketListener.removePlayer(event.getPlayer());
+    }
+
     public void reloadNameplates() {
         this.nameplates.values().forEach(Nameplate::remove);
         this.nameplates.clear();

src/main/java/me/youhavetrouble/notjustnameplates/packets/PacketTeam.java

@@ -0,0 +1,29 @@
+package me.youhavetrouble.notjustnameplates.packets;
+
+import net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.world.scores.PlayerTeam;
+import net.minecraft.world.scores.Team;
+import org.jetbrains.annotations.Nullable;
+
+public class PacketTeam extends PlayerTeam {
+
+    private PacketTeam(String name, ClientboundSetPlayerTeamPacket.Parameters parameters) {
+        super(MinecraftServer.getServer().getScoreboard(), name);
+        if (parameters != null) {
+            Team.CollisionRule collisionRule = Team.CollisionRule.byName(parameters.getCollisionRule());
+            if (collisionRule != null) setCollisionRule(collisionRule);
+            setColor(parameters.getColor());
+            setPlayerPrefix(parameters.getPlayerPrefix());
+            setPlayerSuffix(parameters.getPlayerSuffix());
+            setDisplayName(parameters.getDisplayName());
+            unpackOptions(parameters.getOptions());
+        }
+
+        setNameTagVisibility(Team.Visibility.NEVER);
+    }
+
+    public static PacketTeam create(String name, @Nullable ClientboundSetPlayerTeamPacket.Parameters parameters) {
+        return new PacketTeam(name, parameters);
+    }
+}

src/main/java/me/youhavetrouble/notjustnameplates/packets/TeamPacketListener.java

@@ -0,0 +1,57 @@
+package me.youhavetrouble.notjustnameplates.packets;
+
+import io.netty.channel.*;
+import me.youhavetrouble.notjustnameplates.NotJustNameplates;
+import net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket;
+import org.bukkit.craftbukkit.entity.CraftPlayer;
+import org.bukkit.entity.Player;
+import org.bukkit.scoreboard.Team;
+
+import java.util.Locale;
+
+public class TeamPacketListener extends ChannelDuplexHandler {
+
+    public static final String HANDLER_NAME = "njn_team_packet_handler";
+
+    @Override
+    public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
+        if (!(msg instanceof ClientboundSetPlayerTeamPacket originalPacket)) {
+            super.write(ctx, msg, promise);
+            return;
+        }
+        // if nametag visibility is already never, no need to override the packet
+        if (originalPacket.getParameters().isPresent()) {
+            ClientboundSetPlayerTeamPacket.Parameters parameters = originalPacket.getParameters().get();
+            Team.OptionStatus nametagVisibility = Team.OptionStatus.valueOf(parameters.getNametagVisibility().toUpperCase(Locale.ENGLISH));
+            if (nametagVisibility == Team.OptionStatus.NEVER) {
+                super.write(ctx, msg, promise);
+                return;
+            }
+        }
+
+        NotJustNameplates.getInstance().getLogger().info(msg.toString());
+        PacketTeam packetTeam = PacketTeam.create(originalPacket.getName(), originalPacket.getParameters().orElse(null));
+        ClientboundSetPlayerTeamPacket newPacket = ClientboundSetPlayerTeamPacket.createAddOrModifyPacket(packetTeam, true);
+        super.write(ctx, newPacket, promise);
+    }
+
+
+    public static void addPlayer(Player player) {
+        CraftPlayer craftPlayer = (CraftPlayer) player;
+        Channel channel = craftPlayer.getHandle().connection.connection.channel;
+        ChannelPipeline pipeline = channel.pipeline();
+        if (pipeline.get(HANDLER_NAME) == null) {
+            pipeline.addBefore("packet_handler", HANDLER_NAME, new TeamPacketListener());
+        }
+    }
+
+    public static void removePlayer(Player player) {
+        CraftPlayer craftPlayer = (CraftPlayer) player;
+        Channel channel = craftPlayer.getHandle().connection.connection.channel;
+        ChannelPipeline pipeline = channel.pipeline();
+        if (pipeline.get(HANDLER_NAME) != null) {
+            pipeline.remove(HANDLER_NAME);
+        }
+    }
+
+}