Implement a plugin API for developers

Add a developer-friendly API to Grasscutter

build.gradle

@@ -37,7 +37,7 @@ sourceCompatibility = JavaVersion.VERSION_17
 targetCompatibility = JavaVersion.VERSION_17
 
 group = 'tech.xigam'
-version = '1.0.0-dev'
+version = '1.0.2-dev'
 
 sourceCompatibility = 17
 targetCompatibility = 17

src/main/java/emu/grasscutter/command/commands/CoopCommand.java

@@ -8,13 +8,14 @@ import java.util.List;
 
 @Command(label = "coop", usage = "coop",
         description = "Forces someone to join the world of others", permission = "server.coop")
-public class CoopCommand implements CommandHandler {
+public final class CoopCommand implements CommandHandler {
     @Override
     public void execute(Player sender, List<String> args) {
         if (args.size() < 2) {
             CommandHandler.sendMessage(sender, "Usage: coop <playerId> <target playerId>");
             return;
         }
+        
         try {
             int tid = Integer.parseInt(args.get(0));
             int hostId = Integer.parseInt(args.get(1));

src/main/java/emu/grasscutter/command/commands/GiveAllCommand.java

@@ -15,7 +15,7 @@ import java.util.*;
 
 @Command(label = "giveall", usage = "giveall [player] [amount]",
         description = "Gives all items", aliases = {"givea"}, permission = "player.giveall", threading = true)
-public class GiveAllCommand implements CommandHandler {
+public final class GiveAllCommand implements CommandHandler {
 
     @Override
     public void execute(Player sender, List<String> args) {
@@ -142,16 +142,11 @@ public class GiveAllCommand implements CommandHandler {
             }
         }
 
-       if (testItemsList.contains(itemId)) {
-            return true;
-        }
-
-        return false;
+        return testItemsList.contains(itemId);
     }
 
     static class Range {
-        private int min;
-        private int max;
+        private final int min, max;
 
         public Range(int min, int max) {
             if(min > max){
@@ -159,6 +154,7 @@ public class GiveAllCommand implements CommandHandler {
                 max ^= min;
                 min ^= max;
             }
+            
             this.min = min;
             this.max = max;
         }

src/main/java/emu/grasscutter/command/commands/SendMailCommand.java

@@ -6,24 +6,20 @@ import emu.grasscutter.command.CommandHandler;
 import emu.grasscutter.database.DatabaseHelper;
 import emu.grasscutter.game.mail.Mail;
 import emu.grasscutter.game.player.Player;
-import emu.grasscutter.server.packet.send.PacketMailChangeNotify;
 
-import java.time.Instant;
-import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
-import java.util.Locale;
 
 @Command(label = "sendmail", usage = "sendmail <userId|all|help> [templateId]",
         description = "Sends mail to the specified user. The usage of this command changes based on it's composition state.", permission = "server.sendmail")
-public class SendMailCommand implements CommandHandler {
+public final class SendMailCommand implements CommandHandler {
 
     // TODO: You should be able to do /sendmail and then just send subsequent messages until you finish
     //  However, due to the current nature of the command system, I don't think this is possible without rewriting
     //  the command system (again). For now this will do
 
     // Key = User that is constructing the mail.
-    private static HashMap<Integer, MailBuilder> mailBeingConstructed = new HashMap<Integer, MailBuilder>();
+    private static final HashMap<Integer, MailBuilder> mailBeingConstructed = new HashMap<Integer, MailBuilder>();
 
     // Yes this is awful and I hate it.
     @Override
@@ -48,7 +44,6 @@ public class SendMailCommand implements CommandHandler {
                         default -> {
                             if (DatabaseHelper.getPlayerById(Integer.parseInt(args.get(0))) != null) {
                                 mailBuilder = new MailBuilder(Integer.parseInt(args.get(0)), new Mail());
-                                break;
                             } else {
                                 CommandHandler.sendMessage(sender, "The user with an id of '" + args.get(0) + "' does not exist");
                                 return;
@@ -73,7 +68,7 @@ public class SendMailCommand implements CommandHandler {
                     }
                     case "finish" -> {
                         if (mailBuilder.constructionStage == 3) {
-                            if (mailBuilder.sendToAll == false) {
+                            if (!mailBuilder.sendToAll) {
                                 Grasscutter.getGameServer().getPlayerByUid(mailBuilder.recipient, true).sendMail(mailBuilder.mail);
                                 CommandHandler.sendMessage(sender, "Message sent to user " + mailBuilder.recipient + "!");
                             } else {

src/main/java/emu/grasscutter/command/commands/TpallCommand.java → src/main/java/emu/grasscutter/command/commands/TeleportAllCommand.java

@@ -9,23 +9,25 @@ import java.util.List;
 
 @Command(label = "tpall", usage = "tpall",
         description = "Teleports all players in your world to your position", permission = "player.tpall")
-public class TpallCommand implements CommandHandler {
+public final class TeleportAllCommand implements CommandHandler {
     @Override
     public void execute(Player sender, List<String> args) {
         if (sender == null) {
             CommandHandler.sendMessage(null, "Run this command in-game.");
             return;
         }
+        
         if (!sender.getWorld().isMultiplayer()) {
             CommandHandler.sendMessage(sender, "You only can use this command in MP mode.");
             return;
         }
-        for (Player gp : sender.getWorld().getPlayers()) {
-            if (gp.equals(sender))
+        
+        for (Player player : sender.getWorld().getPlayers()) {
+            if (player.equals(sender))
                 continue;
             Position pos = sender.getPos();
 
-            gp.getWorld().transferPlayerToScene(gp, sender.getSceneId(), pos);
+            player.getWorld().transferPlayerToScene(player, sender.getSceneId(), pos);
         }
     }
 }

src/main/java/emu/grasscutter/game/player/Player.java

@@ -37,6 +37,9 @@ import emu.grasscutter.net.proto.ShowAvatarInfoOuterClass;
 import emu.grasscutter.net.proto.ProfilePictureOuterClass.ProfilePicture;
 import emu.grasscutter.net.proto.SocialDetailOuterClass.SocialDetail;
 import emu.grasscutter.net.proto.SocialShowAvatarInfoOuterClass;
+import emu.grasscutter.server.event.player.PlayerJoinEvent;
+import emu.grasscutter.server.event.player.PlayerQuitEvent;
+import emu.grasscutter.server.event.player.PlayerReceiveMailEvent;
 import emu.grasscutter.server.game.GameServer;
 import emu.grasscutter.server.game.GameSession;
 import emu.grasscutter.server.packet.send.*;
@@ -725,9 +728,13 @@ public class Player {
 	public List<Mail> getAllMail() { return this.mail; }
 
 	public void sendMail(Mail message) {
+		// Call mail receive event.
+		PlayerReceiveMailEvent event = new PlayerReceiveMailEvent(this, message); event.call();
+		if(event.isCanceled()) return; message = event.getMessage();
+		
 		this.mail.add(message);
 		this.save();
-		Grasscutter.getLogger().info("Mail sent to user [" + this.getUid()  + ":" + this.getNickname() + "]!");
+		Grasscutter.getLogger().debug("Mail sent to user [" + this.getUid()  + ":" + this.getNickname() + "]!");
 		if(this.isOnline()) {
 			this.sendPacket(new PacketMailChangeNotify(this, message));
 		} // TODO: setup a way for the mail notification to show up when someone receives mail when they were offline
@@ -1037,6 +1044,11 @@ public class Player {
 
 		// First notify packets sent
 		this.setHasSentAvatarDataNotify(true);
+
+		// Call join event.
+		PlayerJoinEvent event = new PlayerJoinEvent(this); event.call();
+		if(event.isCanceled()) // If event is not cancelled, continue.
+			session.close();
 	}
 
 	public void onLogout() {
@@ -1055,6 +1067,9 @@ public class Player {
 		this.save();
 		this.getTeamManager().saveAvatars();
 		this.getFriendsList().save();
+		
+		// Call quit event.
+		PlayerQuitEvent event = new PlayerQuitEvent(this); event.call();
 	}
 
 	public enum SceneLoadState {

src/main/java/emu/grasscutter/plugin/Plugin.java

 package emu.grasscutter.plugin;
 
 import emu.grasscutter.Grasscutter;
+import emu.grasscutter.plugin.api.ServerHook;
 import emu.grasscutter.server.game.GameServer;
 
+import java.io.File;
+import java.io.InputStream;
+import java.net.URLClassLoader;
+
 /**
  * The base class for all plugins to extend.
  */
 public abstract class Plugin {
+    private final ServerHook server = ServerHook.getInstance();
+    
     private PluginIdentifier identifier;
+    private URLClassLoader classLoader;
+    private File dataFolder;
 
     /**
      * This method is reflected into.
@@ -15,10 +24,20 @@ public abstract class Plugin {
      * Set plugin variables.
      * @param identifier The plugin's identifier.
      */
-    private void initializePlugin(PluginIdentifier identifier) {
-        if(this.identifier == null)
+    private void initializePlugin(PluginIdentifier identifier, URLClassLoader classLoader) {
+        if(this.identifier != null) {
+            Grasscutter.getLogger().warn(this.identifier.name + " had a reinitialization attempt.");
+            return;
+        }
+        
         this.identifier = identifier;
-        else Grasscutter.getLogger().warn(this.identifier.name + " had a reinitialization attempt.");
+        this.classLoader = classLoader;
+        this.dataFolder = new File(Grasscutter.getConfig().PLUGINS_FOLDER, identifier.name);
+        
+        if(!this.dataFolder.exists() && !this.dataFolder.mkdirs()) {
+            Grasscutter.getLogger().warn("Failed to create plugin data folder for " + this.identifier.name);
+            return;
+        }
     }
 
     /**
@@ -55,7 +74,32 @@ public abstract class Plugin {
      * @return A server instance.
      */
     public final GameServer getServer() {
-        return Grasscutter.getGameServer();
+        return this.server.getGameServer();
+    }
+
+    /**
+     * Returns an input stream for a resource in the JAR file.
+     * @param resourceName The name of the resource.
+     * @return An input stream.
+     */
+    public final InputStream getResource(String resourceName) {
+        return this.classLoader.getResourceAsStream(resourceName);
+    }
+
+    /**
+     * Returns a directory where plugins can store data files.
+     * @return A directory on the file system.
+     */
+    public final File getDataFolder() {
+        return this.dataFolder;
+    }
+
+    /**
+     * Returns the server hook.
+     * @return A server hook singleton.
+     */
+    public final ServerHook getHandle() {
+        return this.server;
     }
     
     /* Called when the plugin is first loaded. */

src/main/java/emu/grasscutter/plugin/PluginManager.java

@@ -3,9 +3,9 @@ package emu.grasscutter.plugin;
 import emu.grasscutter.Grasscutter;
 import emu.grasscutter.server.event.Event;
 import emu.grasscutter.server.event.EventHandler;
-import emu.grasscutter.server.event.Listener;
+import emu.grasscutter.server.event.HandlerPriority;
+import emu.grasscutter.utils.EventConsumer;
 import emu.grasscutter.utils.Utils;
-import org.reflections.Reflections;
 
 import java.io.File;
 import java.io.InputStreamReader;
@@ -21,7 +21,7 @@ import java.util.jar.JarFile;
  */
 public final class PluginManager {
     private final Map<String, Plugin> plugins = new HashMap<>();
-    private final Map<Plugin, List<Listener>> listeners = new HashMap<>();
+    private final List<EventHandler<? extends Event>> listeners = new LinkedList<>();
     
     public PluginManager() {
         this.loadPlugins(); // Load all plugins from the plugins directory.
@@ -68,12 +68,12 @@ public final class PluginManager {
                         JarEntry entry = entries.nextElement();
                         if(entry.isDirectory() || !entry.getName().endsWith(".class") || entry.getName().contains("module-info")) continue;
                         String className = entry.getName().replace(".class", "").replace("/", ".");
-                        Class<?> clazz = loader.loadClass(className);
+                        loader.loadClass(className);
                     }
                     
                     Class<?> pluginClass = loader.loadClass(pluginConfig.mainClass);
                     Plugin pluginInstance = (Plugin) pluginClass.getDeclaredConstructor().newInstance();
-                    this.loadPlugin(pluginInstance, PluginIdentifier.fromPluginConfig(pluginConfig));
+                    this.loadPlugin(pluginInstance, PluginIdentifier.fromPluginConfig(pluginConfig), loader);
                     
                     fileReader.close(); // Close the file reader.
                 } catch (ClassNotFoundException ignored) {
@@ -89,14 +89,14 @@ public final class PluginManager {
      * Load the specified plugin.
      * @param plugin The plugin instance.
      */
-    private void loadPlugin(Plugin plugin, PluginIdentifier identifier) {
+    private void loadPlugin(Plugin plugin, PluginIdentifier identifier, URLClassLoader classLoader) {
         Grasscutter.getLogger().info("Loading plugin: " + identifier.name);
         
         // Add the plugin's identifier.
         try {
             Class<Plugin> pluginClass = Plugin.class;
-            Method method = pluginClass.getDeclaredMethod("initializePlugin", PluginIdentifier.class);
-            method.setAccessible(true); method.invoke(plugin, identifier); method.setAccessible(false);
+            Method method = pluginClass.getDeclaredMethod("initializePlugin", PluginIdentifier.class, URLClassLoader.class);
+            method.setAccessible(true); method.invoke(plugin, identifier, classLoader); method.setAccessible(false);
         } catch (Exception ignored) {
             Grasscutter.getLogger().warn("Failed to add plugin identifier: " + identifier.name);
         }
@@ -129,11 +129,10 @@ public final class PluginManager {
 
     /**
      * Registers a plugin's event listener.
-     * @param plugin The plugin instance.
      * @param listener The event listener.
      */
-    public void registerListener(Plugin plugin, Listener listener) {
-        this.listeners.computeIfAbsent(plugin, k -> new ArrayList<>()).add(listener);
+    public void registerListener(EventHandler<? extends Event> listener) {
+        this.listeners.add(listener);
     }
     
     /**
@@ -141,23 +140,31 @@ public final class PluginManager {
      * @param event The event to invoke.
      */
     public void invokeEvent(Event event) {
-        this.listeners.values().stream()
-                .flatMap(Collection::stream)
-                .forEach(listener -> this.invokeOnListener(listener, event));
+        EnumSet.allOf(HandlerPriority.class)
+                .forEach(priority -> this.checkAndFilter(event, priority));
     }
 
     /**
-     * Attempts to invoke the event on the provided listener.
+     * Check an event to handlers for the priority.
+     * @param event The event being called.
+     * @param priority The priority to call for.
      */
-    private void invokeOnListener(Listener listener, Event event) {
-        try {
-            Class<?> listenerClass = listener.getClass();
-            Method[] methods = listenerClass.getMethods();
-            for (Method method : methods) {
-                if(!method.isAnnotationPresent(EventHandler.class)) return;
-                if(!method.getParameterTypes()[0].isAssignableFrom(event.getClass())) return;
-                method.invoke(listener, event);
-            }
-        } catch (Exception ignored) { }
+    private void checkAndFilter(Event event, HandlerPriority priority) {
+        this.listeners.stream()
+                .filter(handler -> handler.handles().isInstance(event))
+                .filter(handler -> handler.getPriority() == priority)
+                .toList().forEach(handler -> this.invokeHandler(event, handler));
+    }
+
+    /**
+     * Performs logic checks then invokes the provided event handler.
+     * @param event The event passed through to the handler.
+     * @param handler The handler to invoke.
+     */
+    @SuppressWarnings("unchecked")
+    private <T extends Event> void invokeHandler(Event event, EventHandler<T> handler) {
+        if(!event.isCanceled() ||
+                (event.isCanceled() && handler.ignoresCanceled())
+        ) handler.getCallback().consume((T) event);
     }
 }
\ No newline at end of file

src/main/java/emu/grasscutter/plugin/api/ServerHook.java

 package emu.grasscutter.plugin.api;
 
+import emu.grasscutter.command.Command;
+import emu.grasscutter.command.CommandHandler;
 import emu.grasscutter.game.player.Player;
+import emu.grasscutter.server.dispatch.DispatchServer;
 import emu.grasscutter.server.game.GameServer;
 
 import java.util.LinkedList;
@@ -11,7 +14,8 @@ import java.util.List;
  */
 public final class ServerHook {
     private static ServerHook instance;
-    private final GameServer server;
+    private final GameServer gameServer;
+    private final DispatchServer dispatchServer;
 
     /**
      * Gets the server hook instance.
@@ -23,19 +27,47 @@ public final class ServerHook {
 
     /**
      * Hooks into a server.
-     * @param server The server to hook into.
+     * @param gameServer The game server to hook into.
+     * @param dispatchServer The dispatch server to hook into.
      */
-    public ServerHook(GameServer server) {
-        this.server = server;
+    public ServerHook(GameServer gameServer, DispatchServer dispatchServer) {
+        this.gameServer = gameServer;
+        this.dispatchServer = dispatchServer;
 
         instance = this;
     }
 
+    /**
+     * @return The game server.
+     */
+    public GameServer getGameServer() {
+        return this.gameServer;
+    }
+
+    /**
+     * @return The dispatch server.
+     */
+    public DispatchServer getDispatchServer() {
+        return this.dispatchServer;
+    }
+
     /**
      * Gets all online players.
      * @return Players connected to the server.
      */
     public List<Player> getOnlinePlayers() {
-        return new LinkedList<>(this.server.getPlayers().values());
+        return new LinkedList<>(this.gameServer.getPlayers().values());
+    }
+
+    /**
+     * Registers a command to the {@link emu.grasscutter.command.CommandMap}.
+     * @param handler The command handler.
+     */
+    public void registerCommand(CommandHandler handler) {
+        Class<? extends CommandHandler> clazz = handler.getClass();
+        if(!clazz.isAnnotationPresent(Command.class))
+            throw new IllegalArgumentException("Command handler must be annotated with @Command.");
+        Command commandData = clazz.getAnnotation(Command.class);
+        this.gameServer.getCommandMap().registerCommand(commandData.label(), handler);
     }
 }
\ No newline at end of file

src/main/java/emu/grasscutter/server/dispatch/DispatchServer.java

@@ -30,6 +30,7 @@ import java.net.BindException;
 import java.net.InetSocketAddress;
 import java.net.URI;
 import java.net.URLDecoder;
+import java.nio.charset.StandardCharsets;
 import java.security.KeyStore;
 import java.util.*;
 
@@ -209,7 +210,7 @@ public final class DispatchServer {
 		return null;
 	}
 	
-	private KeyManagerFactory createKeyManagerFactory(File keystore, String password) throws Exception {
+	private KeyManagerFactory createKeyManagerFactory(File keystore, String password) {
 		char[] pass = password.toCharArray();
 		KeyManagerFactory kmf = null;
 		
@@ -220,8 +221,8 @@ public final class DispatchServer {
 			
 			kmf = KeyManagerFactory.getInstance("SunX509");
 			kmf.init(ks, pass);
-		} catch (Exception e) {
-			throw e;
+		} catch (Exception exception) {
+			Grasscutter.getLogger().error("Unable to load keystore.", exception);
 		}
 		
 		return kmf;
@@ -243,10 +244,9 @@ public final class DispatchServer {
 					try {
 						kmf = createKeyManagerFactory(keystoreFile, "123456");
 						Grasscutter.getLogger().warn(
-							"[Dispatch] The default keystore password was loaded successfully. Please consider setting the password to 123456 in config.json.");
+							"[Dispatch] The default keystore password was loaded successfully. Please consider setting the password to '123456' in config.json.");
 					} catch (Exception e2) {
-						Grasscutter.getLogger().warn("[Dispatch] Error while loading keystore!");
-						e2.printStackTrace();
+						Grasscutter.getLogger().warn("[Dispatch] Error while loading keystore!", e2);
 					}
 				}
 			}
@@ -257,7 +257,7 @@ public final class DispatchServer {
 				server = this.safelyCreateServer(this.getAddress());
 			}
 			
-			HttpsServer httpsServer = null;
+			HttpsServer httpsServer;
 			
 			try {
 				httpsServer = HttpsServer.create(getAddress(), 0);
@@ -339,10 +339,6 @@ public final class DispatchServer {
 					// added.
 					account = DatabaseHelper.createAccountWithId(requestData.account, 0);
 
-					for (String permission : Grasscutter.getConfig().getDispatchOptions().defaultPermissions) {
-						account.addPermission(permission);
-					}
-
 					if (account != null) {
 						responseData.message = "OK";
 						responseData.data.account.uid = account.getId();
@@ -352,6 +348,9 @@ public final class DispatchServer {
 						Grasscutter.getLogger()
 								.info(String.format("[Dispatch] Client %s failed to log in: Account %s created",
 										t.getRemoteAddress(), responseData.data.account.uid));
+						for (String permission : Grasscutter.getConfig().getDispatchOptions().defaultPermissions) {
+							account.addPermission(permission);
+						}
 					} else {
 						responseData.retcode = -201;
 						responseData.message = "Username not found, create failed.";
@@ -575,15 +574,11 @@ public final class DispatchServer {
 
 			if (next > last) {
 				int eqPos = qs.indexOf('=', last);
-				try {
 				if (eqPos < 0 || eqPos > next) {
-						result.put(URLDecoder.decode(qs.substring(last, next), "utf-8"), "");
+					result.put(URLDecoder.decode(qs.substring(last, next), StandardCharsets.UTF_8), "");
 				} else {
-						result.put(URLDecoder.decode(qs.substring(last, eqPos), "utf-8"),
-								URLDecoder.decode(qs.substring(eqPos + 1, next), "utf-8"));
-					}
-				} catch (UnsupportedEncodingException e) {
-					throw new RuntimeException(e); // will never happen, utf-8 support is mandatory for java
+					result.put(URLDecoder.decode(qs.substring(last, eqPos), StandardCharsets.UTF_8),
+							URLDecoder.decode(qs.substring(eqPos + 1, next), StandardCharsets.UTF_8));
 				}
 			}
 			last = next + 1;

src/main/java/emu/grasscutter/server/event/EventHandler.java

 package emu.grasscutter.server.event;
 
-import java.lang.annotation.Retention;
-import java.lang.annotation.RetentionPolicy;
+import emu.grasscutter.Grasscutter;
+import emu.grasscutter.utils.EventConsumer;
 
-/**
- * Declares a class as an event listener/handler.
+public final class EventHandler<T extends Event> {
+    private final Class<T> eventClass;
+    private EventConsumer<T> listener;
+    private HandlerPriority priority;
+    private boolean handleCanceled;
+    
+    public EventHandler(Class<T> eventClass) {
+        this.eventClass = eventClass;
+    }
+
+    /**
+     * Gets which event this handler is handling.
+     * @return An event class.
+     */
+    public Class<T> handles() {
+        return this.eventClass;
+    }
+
+    /**
+     * Returns the callback for the handler.
+     * @return A consumer callback.
+     */
+    public EventConsumer<T> getCallback() {
+        return this.listener;
+    }
+
+    /**
+     * Returns the handler's priority.
+     * @return The priority of the handler.
+     */
+    public HandlerPriority getPriority() {
+        return this.priority;
+    }
+
+    /**
+     * Returns if the handler will ignore cancelled events.
+     * @return The ignore cancelled state.
+     */
+    public boolean ignoresCanceled() {
+        return this.handleCanceled;
+    }
+
+    /**
+     * Sets the callback method for when the event is invoked.
+     * @param listener An event handler method.
+     * @return Method chaining.
+     */
+    public EventHandler<T> listener(EventConsumer<T> listener) {
+        this.listener = listener; return this;
+    }
+
+    /**
+     * Changes the handler's priority in handling events.
+     * @param priority The priority of the handler.
+     * @return Method chaining.
+     */
+    public EventHandler<T> priority(HandlerPriority priority) {
+        this.priority = priority; return this;
+    }
+
+    /**
+     * Sets if the handler will ignore cancelled events.
+     * @param ignore If the handler should ignore cancelled events.
+     * @return Method chaining.
+     */
+    public EventHandler<T> ignore(boolean ignore) {
+        this.handleCanceled = ignore; return this;
+    }
+
+    /**
+     * Registers the handler into the PluginManager.
      */
-@Retention(RetentionPolicy.RUNTIME)
-public @interface EventHandler {
+    public void register() {
+        Grasscutter.getPluginManager().registerListener(this);
+    }
 }
\ No newline at end of file

src/main/java/emu/grasscutter/server/event/HandlerPriority.java

+package emu.grasscutter.server.event;
+
+public enum HandlerPriority {
+    /**
+     * The handler will be called before every other handler.
+     */
+    HIGH,
+
+    /**
+     * The handler will be called the same time as other handlers.
+     */
+    NORMAL,
+
+    /**
+     * The handler will be called after every other handler.
+     */
+    LOW
+}

src/main/java/emu/grasscutter/server/event/Listener.java

-package emu.grasscutter.server.event;
-
-/**
- * Implementing this interface declares a class as an event listener.
- */
-public interface Listener {
-}

src/main/java/emu/grasscutter/server/event/dispatch/QueryAllRegionsEvent.java

 package emu.grasscutter.server.event.dispatch;
 
-import emu.grasscutter.server.event.ServerEvent;
+import emu.grasscutter.server.event.types.ServerEvent;
 
 public final class QueryAllRegionsEvent extends ServerEvent {
     private String regionList;

src/main/java/emu/grasscutter/server/event/dispatch/QueryCurrentRegionEvent.java

 package emu.grasscutter.server.event.dispatch;
 
-import emu.grasscutter.server.event.ServerEvent;
+import emu.grasscutter.server.event.types.ServerEvent;
 
 public final class QueryCurrentRegionEvent extends ServerEvent {
     private String regionInfo;

src/main/java/emu/grasscutter/server/event/game/PlayerCreationEvent.java

+package emu.grasscutter.server.event.game;
+
+import emu.grasscutter.game.player.Player;
+import emu.grasscutter.server.event.types.GameEvent;
+import emu.grasscutter.server.game.GameSession;
+
+public final class PlayerCreationEvent extends GameEvent {
+    private final GameSession session;
+    private Class<? extends Player> playerClass;
+    
+    public PlayerCreationEvent(GameSession session, Class<? extends Player> playerClass) {
+        this.session = session;
+        this.playerClass = playerClass;
+    }
+    
+    public GameSession getSession() {
+        return this.session;
+    }
+    
+    public void setPlayerClass(Class<? extends Player> playerClass) {
+        this.playerClass = playerClass;
+    }
+    
+    public Class<? extends Player> getPlayerClass() {
+        return this.playerClass;
+    }
+}

src/main/java/emu/grasscutter/server/event/game/ReceivePacketEvent.java

 package emu.grasscutter.server.event.game;
 
 import emu.grasscutter.server.event.Cancellable;
-import emu.grasscutter.server.event.ServerEvent;
+import emu.grasscutter.server.event.types.ServerEvent;
 import emu.grasscutter.server.game.GameSession;
 
 public final class ReceivePacketEvent extends ServerEvent implements Cancellable {

src/main/java/emu/grasscutter/server/event/game/SendPacketEvent.java

@@ -2,7 +2,7 @@ package emu.grasscutter.server.event.game;
 
 import emu.grasscutter.net.packet.BasePacket;
 import emu.grasscutter.server.event.Cancellable;
-import emu.grasscutter.server.event.ServerEvent;
+import emu.grasscutter.server.event.types.ServerEvent;
 import emu.grasscutter.server.game.GameSession;
 
 public final class SendPacketEvent extends ServerEvent implements Cancellable {

src/main/java/emu/grasscutter/server/event/game/ServerTickEvent.java

 package emu.grasscutter.server.event.game;
 
-import emu.grasscutter.server.event.ServerEvent;
+import emu.grasscutter.server.event.types.ServerEvent;
 
 public final class ServerTickEvent extends ServerEvent {
     public ServerTickEvent() {

src/main/java/emu/grasscutter/server/event/internal/ServerStartEvent.java

 package emu.grasscutter.server.event.internal;
 
-import emu.grasscutter.server.event.ServerEvent;
+import emu.grasscutter.server.event.types.ServerEvent;
 
 import java.time.OffsetDateTime;