Grasscutter/src/main/java/emu/grasscutter/server/game/GameServerPacketHandler.java

package emu.grasscutter.server.game;

import java.util.Set;

import emu.grasscutter.server.event.game.ReceivePacketEvent;
import org.reflections.Reflections;

import emu.grasscutter.Grasscutter;
import emu.grasscutter.Grasscutter.ServerDebugMode;
import emu.grasscutter.net.packet.Opcodes;
import emu.grasscutter.net.packet.PacketHandler;
import emu.grasscutter.net.packet.PacketOpcodes;
import emu.grasscutter.server.game.GameSession.SessionState;
import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;

import static emu.grasscutter.Configuration.*;

@SuppressWarnings("unchecked")
public class GameServerPacketHandler {
	private final Int2ObjectMap<PacketHandler> handlers;
	
	public GameServerPacketHandler(Class<? extends PacketHandler> handlerClass) {
		this.handlers = new Int2ObjectOpenHashMap<>();
		
		this.registerHandlers(handlerClass);
	}

	public void registerPacketHandler(Class<? extends PacketHandler> handlerClass) {
		try {
			Opcodes opcode = handlerClass.getAnnotation(Opcodes.class);

			if (opcode == null || opcode.disabled() || opcode.value() <= 0) {
				return;
			}

			PacketHandler packetHandler = (PacketHandler) handlerClass.newInstance();

			this.handlers.put(opcode.value(), packetHandler);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public void registerHandlers(Class<? extends PacketHandler> handlerClass) {
		Reflections reflections = new Reflections("emu.grasscutter.server.packet");
		Set<?> handlerClasses = reflections.getSubTypesOf(handlerClass);
		
		for (Object obj : handlerClasses) {
			this.registerPacketHandler((Class<? extends PacketHandler>) obj);
		}
		
		// Debug
		Grasscutter.getLogger().info("Registered " + this.handlers.size() + " " + handlerClass.getSimpleName() + "s");
	}
	
	public void handle(GameSession session, int opcode, byte[] header, byte[] payload) {
		PacketHandler handler = this.handlers.get(opcode);
		
		if (handler != null) {
			try {
				// Make sure session is ready for packets
				SessionState state = session.getState();
				
				if (opcode == PacketOpcodes.PingReq) {
					// Always continue if packet is ping request
				} else if (opcode == PacketOpcodes.GetPlayerTokenReq) {
					if (state != SessionState.WAITING_FOR_TOKEN) {
						return;
					}
				} else if (opcode == PacketOpcodes.PlayerLoginReq) {
					if (state != SessionState.WAITING_FOR_LOGIN) {
						return;
					}
				} else if (opcode == PacketOpcodes.SetPlayerBornDataReq) {
					if (state != SessionState.PICKING_CHARACTER) {
						return;
					}
				} else {
					if (state != SessionState.ACTIVE) {
						return;
					}
				}
				
				// Invoke event.
				ReceivePacketEvent event = new ReceivePacketEvent(session, opcode, payload); event.call();
				if(!event.isCanceled()) // If event is not canceled, continue.
					handler.handle(session, header, event.getPacketData());				
			} catch (Exception ex) {
				// TODO Remove this when no more needed
				ex.printStackTrace();
			}
			return; // Packet successfully handled
		}
		
		// Log unhandled packets
		if (SERVER.debugLevel == ServerDebugMode.MISSING) {
			Grasscutter.getLogger().info("Unhandled packet (" + opcode + "): " + emu.grasscutter.net.packet.PacketOpcodesUtil.getOpcodeName(opcode));
		}
	}
}