minecraft-src/net/minecraft/server/chase/ChaseClient.java

package net.minecraft.server.chase;

import com.google.common.base.Charsets;
import com.mojang.logging.LogUtils;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.StringReader;
import java.net.Socket;
import java.util.List;
import java.util.Locale;
import java.util.NoSuchElementException;
import java.util.Optional;
import java.util.Scanner;
import net.minecraft.commands.CommandSourceStack;
import net.minecraft.commands.Commands;
import net.minecraft.network.chat.CommonComponents;
import net.minecraft.resources.ResourceKey;
import net.minecraft.server.MinecraftServer;
import net.minecraft.server.commands.ChaseCommand;
import net.minecraft.server.level.ServerLevel;
import net.minecraft.server.level.ServerPlayer;
import net.minecraft.world.level.Level;
import net.minecraft.world.phys.Vec2;
import net.minecraft.world.phys.Vec3;
import org.apache.commons.io.IOUtils;
import org.jetbrains.annotations.Nullable;
import org.slf4j.Logger;

public class ChaseClient {
	private static final Logger LOGGER = LogUtils.getLogger();
	private static final int RECONNECT_INTERVAL_SECONDS = 5;
	private final String serverHost;
	private final int serverPort;
	private final MinecraftServer server;
	private volatile boolean wantsToRun;
	@Nullable
	private Socket socket;
	@Nullable
	private Thread thread;

	public ChaseClient(String serverHost, int serverPort, MinecraftServer server) {
		this.serverHost = serverHost;
		this.serverPort = serverPort;
		this.server = server;
	}

	public void start() {
		if (this.thread != null && this.thread.isAlive()) {
			LOGGER.warn("Remote control client was asked to start, but it is already running. Will ignore.");
		}

		this.wantsToRun = true;
		this.thread = new Thread(this::run, "chase-client");
		this.thread.setDaemon(true);
		this.thread.start();
	}

	public void stop() {
		this.wantsToRun = false;
		IOUtils.closeQuietly(this.socket);
		this.socket = null;
		this.thread = null;
	}

	public void run() {
		String string = this.serverHost + ":" + this.serverPort;

		while (this.wantsToRun) {
			try {
				LOGGER.info("Connecting to remote control server {}", string);
				this.socket = new Socket(this.serverHost, this.serverPort);
				LOGGER.info("Connected to remote control server! Will continuously execute the command broadcasted by that server.");

				try {
					BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(this.socket.getInputStream(), Charsets.US_ASCII));

					try {
						while (this.wantsToRun) {
							String string2 = bufferedReader.readLine();
							if (string2 == null) {
								LOGGER.warn("Lost connection to remote control server {}. Will retry in {}s.", string, 5);
								break;
							}

							this.handleMessage(string2);
						}
					} catch (Throwable var7) {
						try {
							bufferedReader.close();
						} catch (Throwable var6) {
							var7.addSuppressed(var6);
						}

						throw var7;
					}

					bufferedReader.close();
				} catch (IOException var8) {
					LOGGER.warn("Lost connection to remote control server {}. Will retry in {}s.", string, 5);
				}
			} catch (IOException var9) {
				LOGGER.warn("Failed to connect to remote control server {}. Will retry in {}s.", string, 5);
			}

			if (this.wantsToRun) {
				try {
					Thread.sleep(5000L);
				} catch (InterruptedException var5) {
				}
			}
		}
	}

	private void handleMessage(String message) {
		try {
			Scanner scanner = new Scanner(new StringReader(message));

			try {
				scanner.useLocale(Locale.ROOT);
				String string = scanner.next();
				if ("t".equals(string)) {
					this.handleTeleport(scanner);
				} else {
					LOGGER.warn("Unknown message type '{}'", string);
				}
			} catch (Throwable var6) {
				try {
					scanner.close();
				} catch (Throwable var5) {
					var6.addSuppressed(var5);
				}

				throw var6;
			}

			scanner.close();
		} catch (NoSuchElementException var7) {
			LOGGER.warn("Could not parse message '{}', ignoring", message);
		}
	}

	private void handleTeleport(Scanner scanner) {
		this.parseTarget(scanner)
			.ifPresent(
				teleportTarget -> this.executeCommand(
					String.format(
						Locale.ROOT,
						"execute in %s run tp @s %.3f %.3f %.3f %.3f %.3f",
						teleportTarget.level.location(),
						teleportTarget.pos.x,
						teleportTarget.pos.y,
						teleportTarget.pos.z,
						teleportTarget.rot.y,
						teleportTarget.rot.x
					)
				)
			);
	}

	private Optional<ChaseClient.TeleportTarget> parseTarget(Scanner scanner) {
		ResourceKey<Level> resourceKey = (ResourceKey<Level>)ChaseCommand.DIMENSION_NAMES.get(scanner.next());
		if (resourceKey == null) {
			return Optional.empty();
		} else {
			float f = scanner.nextFloat();
			float g = scanner.nextFloat();
			float h = scanner.nextFloat();
			float i = scanner.nextFloat();
			float j = scanner.nextFloat();
			return Optional.of(new ChaseClient.TeleportTarget(resourceKey, new Vec3(f, g, h), new Vec2(j, i)));
		}
	}

	private void executeCommand(String command) {
		this.server
			.execute(
				() -> {
					List<ServerPlayer> list = this.server.getPlayerList().getPlayers();
					if (!list.isEmpty()) {
						ServerPlayer serverPlayer = (ServerPlayer)list.get(0);
						ServerLevel serverLevel = this.server.overworld();
						CommandSourceStack commandSourceStack = new CommandSourceStack(
							serverPlayer.commandSource(),
							Vec3.atLowerCornerOf(serverLevel.getSharedSpawnPos()),
							Vec2.ZERO,
							serverLevel,
							4,
							"",
							CommonComponents.EMPTY,
							this.server,
							serverPlayer
						);
						Commands commands = this.server.getCommands();
						commands.performPrefixedCommand(commandSourceStack, command);
					}
				}
			);
	}

	record TeleportTarget(ResourceKey<Level> level, Vec3 pos, Vec2 rot) {
	}
}