feat: assume class based off packet ID, returning a ModAPIMessage

Author: RedVortexDev

src/main/java/com/mcdiamondfire/proto/ModAPIMessage.java

@@ -0,0 +1,13 @@
+package com.mcdiamondfire.proto;
+
+import com.google.protobuf.Message;
+
+/**
+ * Represents a deserialized ModAPI message.
+ *
+ * @param id      the unique identifier of the ModAPI message type
+ * @param message the deserialized Protocol Message instance
+ */
+public record ModAPIMessage(String id, Message message) {
+
+}

src/main/java/com/mcdiamondfire/proto/ModAPIUtility.java

@@ -5,6 +5,7 @@
 import com.google.protobuf.util.JsonFormat;
 
 import java.lang.reflect.InvocationTargetException;
+import java.util.Optional;
 
 /**
  * Utility class for serializing ModAPI messages to JSON format.
@@ -28,33 +29,38 @@ private ModAPIUtility() {
 	public static String serializeMessage(final Message message) throws InvalidProtocolBufferException {
 		final String json = JsonFormat.printer().print(message);
 		final JsonObject jsonObject = JsonParser.parseString(json).getAsJsonObject();
-		jsonObject.add("packet_id", new JsonPrimitive(ModAPIMessages.getMessageId(message.getClass())));
+		final Optional<String> messageId = ModAPIMessages.getMessageId(message.getClass());
+		if (messageId.isEmpty()) {
+			throw new IllegalArgumentException("Message class not registered: " + message.getClass().getName());
+		}
+		jsonObject.add("packet_id", new JsonPrimitive(messageId.get()));
 		return jsonObject.toString();
 	}
 
 	/**
-	 * Deserializes a JSON string back into a Protocol Message of the specified class.
+	 * Deserializes a JSON string back into a {@link ModAPIMessage}.
 	 *
-	 * @param json  the JSON string to deserialize
-	 * @param clazz the class of the Protocol Message to deserialize into
-	 * @param <T>   the type of the Protocol Message
-	 * @return the deserialized Protocol Message
+	 * @param json the JSON string to deserialize
+	 * @return the deserialized Protocol Message and its ID wrapped in a {@link ModAPIMessage}
 	 * @throws InvalidProtocolBufferException if deserialization fails
 	 * @throws JsonSyntaxException            if the JSON is not properly formatted
 	 * @throws IllegalStateException          if the JSON does not contain a valid packet ID
 	 * @throws RuntimeException               if reflection fails to create a new builder instance
-	 * @throws ClassCastException             if the built message is not of the expected type
+	 * @throws ClassCastException             if the packet ID is not of the expected type
 	 */
-	public static <T extends Message> T deserializeMessage(final String json, final Class<T> clazz) throws InvalidProtocolBufferException {
+	public static ModAPIMessage deserializeMessage(final String json) throws InvalidProtocolBufferException {
 		try {
 			final JsonObject jsonObject = JsonParser.parseString(json).getAsJsonObject();
-			jsonObject.remove("packet_id").getAsString();
+			final String packetId = jsonObject.remove("packet_id").getAsString();
 			final String cleanedJson = jsonObject.toString();
 
-			final Message.Builder builder = (Message.Builder) clazz.getMethod("newBuilder").invoke(null);
+			final Optional<Class<? extends Message>> clazz = ModAPIMessages.getMessageClass(packetId);
+			if (clazz.isEmpty()) {
+				throw new IllegalStateException("No message class registered for packet ID: " + packetId);
+			}
+			final Message.Builder builder = (Message.Builder) clazz.get().getMethod("newBuilder").invoke(null);
 			JSON_PARSER.merge(cleanedJson, builder);
-			//noinspection unchecked -- on the caller to ensure the type is correct.
-			return (T) builder.build();
+			return new ModAPIMessage(packetId, builder.build());
 		} catch (final NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
 			throw new RuntimeException("Failed to deserialize message.", e);
 		}