ViaVersion/velocity/src/main/java/com/viaversion/viaversion/velocity/platform/VelocityViaInjector.java

/*
 * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
 * Copyright (C) 2016-2024 ViaVersion and contributors
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.viaversion.viaversion.velocity.platform;

import com.google.gson.JsonObject;
import com.viaversion.viaversion.VelocityPlugin;
import com.viaversion.viaversion.api.Via;
import com.viaversion.viaversion.api.platform.ViaInjector;
import com.viaversion.viaversion.api.protocol.version.ProtocolVersion;
import com.viaversion.viaversion.util.ReflectionUtil;
import com.viaversion.viaversion.velocity.handlers.VelocityChannelInitializer;
import io.netty.channel.ChannelInitializer;
import it.unimi.dsi.fastutil.ints.IntLinkedOpenHashSet;
import it.unimi.dsi.fastutil.ints.IntSortedSet;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.logging.Level;
import org.jetbrains.annotations.Nullable;


public class VelocityViaInjector implements ViaInjector {
    public static final Method GET_PLAYER_INFO_FORWARDING_MODE = getPlayerInfoForwardingModeMethod();

    private static @Nullable Method getPlayerInfoForwardingModeMethod() {
        try {
            return Class.forName("com.velocitypowered.proxy.config.VelocityConfiguration").getMethod("getPlayerInfoForwardingMode");
        } catch (NoSuchMethodException | ClassNotFoundException e) {
            Via.getPlatform().getLogger().log(Level.SEVERE, "Failed to get getPlayerInfoForwardingMode method from Velocity, please report this issue on our GitHub.", e);
            return null;
        }
    }

    private ChannelInitializer getInitializer() throws Exception {
        Object connectionManager = ReflectionUtil.get(VelocityPlugin.PROXY, "cm", Object.class);
        Object channelInitializerHolder = ReflectionUtil.invoke(connectionManager, "getServerChannelInitializer");
        return (ChannelInitializer) ReflectionUtil.invoke(channelInitializerHolder, "get");
    }

    private ChannelInitializer getBackendInitializer() throws Exception {
        Object connectionManager = ReflectionUtil.get(VelocityPlugin.PROXY, "cm", Object.class);
        Object channelInitializerHolder = ReflectionUtil.invoke(connectionManager, "getBackendChannelInitializer");
        return (ChannelInitializer) ReflectionUtil.invoke(channelInitializerHolder, "get");
    }

    @Override
    public void inject() throws Exception {
        Via.getPlatform().getLogger().info("Replacing channel initializers; you can safely ignore the following two warnings.");

        Object connectionManager = ReflectionUtil.get(VelocityPlugin.PROXY, "cm", Object.class);
        Object channelInitializerHolder = ReflectionUtil.invoke(connectionManager, "getServerChannelInitializer");
        ChannelInitializer originalInitializer = getInitializer();
        channelInitializerHolder.getClass().getMethod("set", ChannelInitializer.class)
                .invoke(channelInitializerHolder, new VelocityChannelInitializer(originalInitializer, false));

        Object backendInitializerHolder = ReflectionUtil.invoke(connectionManager, "getBackendChannelInitializer");
        ChannelInitializer backendInitializer = getBackendInitializer();
        backendInitializerHolder.getClass().getMethod("set", ChannelInitializer.class)
                .invoke(backendInitializerHolder, new VelocityChannelInitializer(backendInitializer, true));
    }

    @Override
    public void uninject() {
        Via.getPlatform().getLogger().severe("ViaVersion cannot remove itself from Velocity without a reboot!");
    }

    @Override
    public int getServerProtocolVersion() throws Exception {
        return getLowestSupportedProtocolVersion();
    }

    @Override
    public IntSortedSet getServerProtocolVersions() throws Exception {
        int lowestSupportedProtocolVersion = getLowestSupportedProtocolVersion();

        IntSortedSet set = new IntLinkedOpenHashSet();
        for (com.velocitypowered.api.network.ProtocolVersion version : com.velocitypowered.api.network.ProtocolVersion.SUPPORTED_VERSIONS) {
            if (version.getProtocol() >= lowestSupportedProtocolVersion) {
                set.add(version.getProtocol());
            }
        }
        return set;
    }

    public static int getLowestSupportedProtocolVersion() {
        try {
            if (GET_PLAYER_INFO_FORWARDING_MODE != null
                    && ((Enum<?>) GET_PLAYER_INFO_FORWARDING_MODE.invoke(VelocityPlugin.PROXY.getConfiguration()))
                    .name().equals("MODERN")) {
                return ProtocolVersion.v1_13.getVersion();
            }
        } catch (IllegalAccessException | InvocationTargetException ignored) {
        }
        return com.velocitypowered.api.network.ProtocolVersion.MINIMUM_VERSION.getProtocol();
    }

    @Override
    public JsonObject getDump() {
        JsonObject data = new JsonObject();
        try {
            data.addProperty("currentInitializer", getInitializer().getClass().getName());
        } catch (Exception e) {
            // Ignored
        }
        return data;
    }
}