feat: update LabyMod extension to neo packet format (#128)

LabyMod released a v4 (neo) version last year, we can by this point assume that most active users migrated to v4. Therefore the LabyMod extension can now use the new LabyMod neo protocol instead of the legacy v3 protocol.

ext/labymod/src/main/java/com/github/juliarn/npclib/ext/labymod/BufferUtil.java

@@ -25,8 +25,8 @@
 package com.github.juliarn.npclib.ext.labymod;
 
 import java.nio.ByteBuffer;
-import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
+import java.util.UUID;
 import org.jetbrains.annotations.NotNull;
 
 final class BufferUtil {
@@ -62,23 +62,13 @@ private BufferUtil() {
     }
   }
 
-  public static @NotNull ByteBuffer putString(@NotNull ByteBuffer buffer, @NotNull String string) {
-    // get the bytes of the buffer to write
-    byte[] bytes = string.getBytes(StandardCharsets.UTF_8);
-
-    // write the content
-    ByteBuffer writeBuffer = putVarInt(buffer, bytes.length);
-    writeBuffer = putBytes(writeBuffer, bytes);
-
+  public static @NotNull ByteBuffer putUUID(@NotNull ByteBuffer buffer, @NotNull UUID uuid) {
+    ByteBuffer writeBuffer = ensureWriteable(buffer, Long.BYTES * 2);
+    writeBuffer.putLong(uuid.getMostSignificantBits());
+    writeBuffer.putLong(uuid.getLeastSignificantBits());
     return writeBuffer;
   }
 
-  public static @NotNull ByteBuffer putBytes(@NotNull ByteBuffer buffer, byte[] bytes) {
-    // ensure that the target buffer has enough space to fit the bytes and write them
-    ByteBuffer writeBuffer = ensureWriteable(buffer, bytes.length);
-    return writeBuffer.put(bytes);
-  }
-
   public static @NotNull ByteBuffer putVarInt(@NotNull ByteBuffer buffer, int value) {
     // ensure that the target buffer has enough space to fit the var int
     int varIntBytes = VAR_INT_BYTE_LENGTHS[Integer.numberOfLeadingZeros(value)];

ext/labymod/src/main/java/com/github/juliarn/npclib/ext/labymod/LabyModExtension.java

@@ -26,77 +26,65 @@
 
 import com.github.juliarn.npclib.api.protocol.OutboundPacket;
 import com.github.juliarn.npclib.api.protocol.PlatformPacketAdapter;
-import com.google.gson.JsonArray;
-import com.google.gson.JsonObject;
 import java.nio.ByteBuffer;
-import java.util.UUID;
+import java.util.function.UnaryOperator;
 import org.jetbrains.annotations.NotNull;
 
 public final class LabyModExtension {
 
-  private static final String EMOTE_ID_PROPERTY = "emote_id";
-  private static final String STICKER_ID_PROPERTY = "sticker_id";
+  // full list of packet ids can be found here:
+  // https://github.com/LabyMod/labymod4-server-api/blob/master/core/src/main/java/net/labymod/serverapi/core/LabyModProtocol.java
+  private static final int EMOTE_PACKET_ID = 16;
+  private static final int SPRAY_PACKET_ID = 17;
+  private static final String LM_PLUGIN_CHANNEL = "labymod:neo";
 
-  private static final String EMOTE_API_MESSAGE_KEY = "emote_api";
-  private static final String STICKER_API_MESSAGE_KEY = "sticker_api";
-
-  private static final String LM_PLUGIN_CHANNEL = "labymod3:main";
-
-  private static final int DEFAULT_BUFFER_ALLOCATION_BYTES = 128;
+  // a sensitive default for users that only send out a single sticker or emote via one packet
+  private static final int DEFAULT_BUFFER_ALLOCATION_BYTES = 32;
 
   private LabyModExtension() {
     throw new UnsupportedOperationException();
   }
 
+  // list of emote ids can be found here:
+  // https://dev.labymod.net/pages/server/labymod/features/emotes
   public static <W, P, I, E> @NotNull OutboundPacket<W, P, I, E> createEmotePacket(
     @NotNull PlatformPacketAdapter<W, P, I, E> packetAdapter,
     int... emoteIds
   ) {
     return (player, npc) -> {
-      // construct the data we need to write
-      JsonArray data = createIdJsonData(EMOTE_ID_PROPERTY, npc.profile().uniqueId(), emoteIds);
-      byte[] payloadData = constructPayloadData(EMOTE_API_MESSAGE_KEY, data.toString());
+      byte[] payloadData = constructPayloadData(EMOTE_PACKET_ID, buffer -> {
+        // put the amount of emotes to send into the buffer & write each emote into the buffer
+        // an emote is also prefixed with the npc uuid which is always the target npc id in our case
+        ByteBuffer target = BufferUtil.putVarInt(buffer, emoteIds.length);
+        for (int emoteId : emoteIds) {
+          target = BufferUtil.putUUID(target, npc.profile().uniqueId());
+          target = BufferUtil.putVarInt(target, emoteId);
+        }
+        return target;
+      });
 
       // create a new plugin message outbound packet and schedule the payload data
       packetAdapter.createCustomPayloadPacket(LM_PLUGIN_CHANNEL, payloadData).schedule(player, npc);
     };
   }
 
+  // currently not supported by the LM api
   public static <W, P, I, E> @NotNull OutboundPacket<W, P, I, E> createStickerPacket(
     @NotNull PlatformPacketAdapter<W, P, I, E> packetAdapter,
     int... stickerIds
   ) {
     return (player, npc) -> {
-      // construct the data we need to write
-      JsonArray data = createIdJsonData(STICKER_ID_PROPERTY, npc.profile().uniqueId(), stickerIds);
-      byte[] payloadData = constructPayloadData(STICKER_API_MESSAGE_KEY, data.toString());
-
-      // create a new plugin message outbound packet and schedule the payload data
-      packetAdapter.createCustomPayloadPacket(LM_PLUGIN_CHANNEL, payloadData).schedule(player, npc);
     };
   }
 
-  private static byte[] constructPayloadData(@NotNull String apiMessageKey, @NotNull String data) {
+  private static byte[] constructPayloadData(int packetId, @NotNull UnaryOperator<ByteBuffer> packetWriter) {
     ByteBuffer buffer = ByteBuffer.allocate(DEFAULT_BUFFER_ALLOCATION_BYTES);
 
     // put the message key, then the data
-    buffer = BufferUtil.putString(buffer, apiMessageKey);
-    buffer = BufferUtil.putString(buffer, data);
+    buffer = BufferUtil.putVarInt(buffer, packetId);
+    buffer = packetWriter.apply(buffer);
 
     // get the buffer content
     return BufferUtil.extractData(buffer);
   }
-
-  private static @NotNull JsonArray createIdJsonData(@NotNull String idProperty, @NotNull UUID npcId, int... ids) {
-    // put the id api data
-    JsonArray array = new JsonArray();
-    for (int id : ids) {
-      JsonObject object = new JsonObject();
-      object.addProperty(idProperty, id);
-      object.addProperty("uuid", npcId.toString());
-      array.add(object);
-    }
-
-    return array;
-  }
 }