minecraft-src/net/minecraft/server/commands/ChaseCommand.java

package net.minecraft.server.commands;

import com.google.common.collect.BiMap;
import com.google.common.collect.ImmutableBiMap;
import com.mojang.brigadier.CommandDispatcher;
import com.mojang.brigadier.arguments.IntegerArgumentType;
import com.mojang.brigadier.arguments.StringArgumentType;
import com.mojang.logging.LogUtils;
import java.io.IOException;
import net.minecraft.commands.CommandSourceStack;
import net.minecraft.commands.Commands;
import net.minecraft.network.chat.Component;
import net.minecraft.resources.ResourceKey;
import net.minecraft.server.chase.ChaseClient;
import net.minecraft.server.chase.ChaseServer;
import net.minecraft.world.level.Level;
import org.jetbrains.annotations.Nullable;
import org.slf4j.Logger;

public class ChaseCommand {
	private static final Logger LOGGER = LogUtils.getLogger();
	private static final String DEFAULT_CONNECT_HOST = "localhost";
	private static final String DEFAULT_BIND_ADDRESS = "0.0.0.0";
	private static final int DEFAULT_PORT = 10000;
	private static final int BROADCAST_INTERVAL_MS = 100;
	public static BiMap<String, ResourceKey<Level>> DIMENSION_NAMES = ImmutableBiMap.of("o", Level.OVERWORLD, "n", Level.NETHER, "e", Level.END);
	@Nullable
	private static ChaseServer chaseServer;
	@Nullable
	private static ChaseClient chaseClient;

	public static void register(CommandDispatcher<CommandSourceStack> dispatcher) {
		dispatcher.register(
			Commands.literal("chase")
				.then(
					Commands.literal("follow")
						.then(
							Commands.argument("host", StringArgumentType.string())
								.executes(commandContext -> follow(commandContext.getSource(), StringArgumentType.getString(commandContext, "host"), 10000))
								.then(
									Commands.argument("port", IntegerArgumentType.integer(1, 65535))
										.executes(
											commandContext -> follow(
												commandContext.getSource(), StringArgumentType.getString(commandContext, "host"), IntegerArgumentType.getInteger(commandContext, "port")
											)
										)
								)
						)
						.executes(commandContext -> follow(commandContext.getSource(), "localhost", 10000))
				)
				.then(
					Commands.literal("lead")
						.then(
							Commands.argument("bind_address", StringArgumentType.string())
								.executes(commandContext -> lead(commandContext.getSource(), StringArgumentType.getString(commandContext, "bind_address"), 10000))
								.then(
									Commands.argument("port", IntegerArgumentType.integer(1024, 65535))
										.executes(
											commandContext -> lead(
												commandContext.getSource(), StringArgumentType.getString(commandContext, "bind_address"), IntegerArgumentType.getInteger(commandContext, "port")
											)
										)
								)
						)
						.executes(commandContext -> lead(commandContext.getSource(), "0.0.0.0", 10000))
				)
				.then(Commands.literal("stop").executes(commandContext -> stop(commandContext.getSource())))
		);
	}

	private static int stop(CommandSourceStack source) {
		if (chaseClient != null) {
			chaseClient.stop();
			source.sendSuccess(() -> Component.literal("You have now stopped chasing"), false);
			chaseClient = null;
		}

		if (chaseServer != null) {
			chaseServer.stop();
			source.sendSuccess(() -> Component.literal("You are no longer being chased"), false);
			chaseServer = null;
		}

		return 0;
	}

	private static boolean alreadyRunning(CommandSourceStack source) {
		if (chaseServer != null) {
			source.sendFailure(Component.literal("Chase server is already running. Stop it using /chase stop"));
			return true;
		} else if (chaseClient != null) {
			source.sendFailure(Component.literal("You are already chasing someone. Stop it using /chase stop"));
			return true;
		} else {
			return false;
		}
	}

	private static int lead(CommandSourceStack source, String bindAddress, int port) {
		if (alreadyRunning(source)) {
			return 0;
		} else {
			chaseServer = new ChaseServer(bindAddress, port, source.getServer().getPlayerList(), 100);

			try {
				chaseServer.start();
				source.sendSuccess(
					() -> Component.literal("Chase server is now running on port " + port + ". Clients can follow you using /chase follow <ip> <port>"), false
				);
			} catch (IOException var4) {
				LOGGER.error("Failed to start chase server", (Throwable)var4);
				source.sendFailure(Component.literal("Failed to start chase server on port " + port));
				chaseServer = null;
			}

			return 0;
		}
	}

	private static int follow(CommandSourceStack source, String host, int port) {
		if (alreadyRunning(source)) {
			return 0;
		} else {
			chaseClient = new ChaseClient(host, port, source.getServer());
			chaseClient.start();
			source.sendSuccess(
				() -> Component.literal(
					"You are now chasing "
						+ host
						+ ":"
						+ port
						+ ". If that server does '/chase lead' then you will automatically go to the same position. Use '/chase stop' to stop chasing."
				),
				false
			);
			return 0;
		}
	}
}