extras/src/main/java/pw/kaboom/extras/modules/server/ServerCommand.java

package pw.kaboom.extras.modules.server;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.bukkit.block.CommandBlock;
import org.bukkit.command.BlockCommandSender;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.minecart.CommandMinecart;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.server.ServerCommandEvent;

public final class ServerCommand implements Listener {
	private static Pattern asAtPattern = Pattern.compile("\\b(as|at|facing entity) @[ae]\\b");

	public static boolean checkExecuteCommand(final String cmd) {
		return ("execute".equalsIgnoreCase(cmd)
			|| "banlist".equalsIgnoreCase(cmd)
			|| "clone".equalsIgnoreCase(cmd)
			|| "data".equalsIgnoreCase(cmd)
			|| "datapack".equalsIgnoreCase(cmd)
			|| "debug".equalsIgnoreCase(cmd)
			|| "difficulty".equalsIgnoreCase(cmd)
			|| "fill".equalsIgnoreCase(cmd)
			|| "forceload".equalsIgnoreCase(cmd)
			|| "help".equalsIgnoreCase(cmd)
			|| "kick".equalsIgnoreCase(cmd)
			|| "list".equalsIgnoreCase(cmd)
			|| "locate".equalsIgnoreCase(cmd)
			|| "locatebiome".equalsIgnoreCase(cmd)
			|| "me".equalsIgnoreCase(cmd)
			|| "msg".equalsIgnoreCase(cmd)
			|| "reload".equalsIgnoreCase(cmd)
			|| "save-all".equalsIgnoreCase(cmd)
			|| "say".equalsIgnoreCase(cmd)
			|| "seed".equalsIgnoreCase(cmd)
			|| "setblock".equalsIgnoreCase(cmd)
			|| "spreadplayers".equalsIgnoreCase(cmd)
			|| "stop".equalsIgnoreCase(cmd)
			|| "summon".equalsIgnoreCase(cmd)
			|| "teammsg".equalsIgnoreCase(cmd)
			|| "teleport".equalsIgnoreCase(cmd)
			|| "tell".equalsIgnoreCase(cmd)
			|| "tellraw".equalsIgnoreCase(cmd)
			|| "tm".equalsIgnoreCase(cmd)
			|| "tp".equalsIgnoreCase(cmd)
			|| "w".equalsIgnoreCase(cmd)
			|| "whitelist".equalsIgnoreCase(cmd)
		);
	}
	public static String checkCommand(final CommandSender sender, final String command, final boolean isConsoleCommand) {
		final String[] arr = command.split(" ");
		String commandName = arr[0].toLowerCase();

		if (isConsoleCommand) {
			commandName = "/" + arr[0].toLowerCase();
		}

		for (int i = 1; i < arr.length; i++) {
			if (arr[i].matches("^[+-]?(?:\\d+\\.?\\d*|\\d*\\.?\\d+)[\\r\\n]*$")) {
				try {
					int integer = Integer.parseInt(arr[i]);
					try {
						if (integer >= Integer.MAX_VALUE) {
							return "cancel";
						}
					} catch (Exception e) {
						return "cancel";
					}

				} catch (NumberFormatException e) {
					// Ignore exception
				}

			}
		}

		try {
			switch (commandName) {
				case "/minecraft:execute":
				case "/execute":
					if (arr.length >= 2) {
						int asAtCount = 0;
						Matcher asAtMatcher = asAtPattern.matcher(command.toLowerCase());
						while (asAtMatcher.find()) {
							asAtCount++;
						}
						if (asAtCount >= 2) {
							return "cancel";
						}

						for (int i = 1; i < arr.length; i++) {
							if ("run".equalsIgnoreCase(arr[i])) {
								if (i + 1 < arr.length) {
									if (checkExecuteCommand(arr[i + 1])) {
										return "cancel";
									} else if (i + 3 < arr.length
											&& "gamerule".equalsIgnoreCase(arr[i + 1])) {
										if ("randomTickSpeed".equalsIgnoreCase(arr[i + 2])
												&& Double.parseDouble(arr[i + 3]) > 6) {
											return command.replaceFirst("(?i)" + "randomTickSpeed " + arr[i + 3], "randomTickSpeed 6");
										}
									} else if ("give".equalsIgnoreCase(arr[i + 1])) {
										if (Double.parseDouble(arr[arr.length - 1]) > 64) {
											arr[arr.length - 1] = "64";
											return String.join(" ", arr);
										}
									} else if ("bossbar".equalsIgnoreCase(arr[i + 1])
									        || "fill".equalsIgnoreCase(arr[i + 1])
									        || "setblock".equalsIgnoreCase(arr[i + 1])
									        || "tellraw".equalsIgnoreCase(arr[i + 1])
									        || "title".equalsIgnoreCase(arr[i + 1])) {
										final String charCommand = parseCharCodes(command);
										if (charCommand.contains("selector")) {
											return "cancel";
										}
									}
								}
								break;
							}
						}
					}
					break;
				case "/minecraft:fill":
				case "/fill":
					if (command.contains("auto")) {
						return command.replace("auto", "[auto]");
					}
					if (command.contains("selector")) {
						return "cancel";
					}
				case "/minecraft:gamerule":
				case "/gamerule":
					if (arr.length >= 3) {
						if ("randomTickSpeed".equalsIgnoreCase(arr[1])
								&& Double.parseDouble(arr[2]) > 6) {
							return command.replaceFirst(arr[2], "6");
						}
					}
					break;
				case "/minecraft:give":
				case "/give":
					if (Double.parseDouble(arr[arr.length - 1]) > 64) {
						arr[arr.length - 1] = "64";
						return String.join(" ", arr);
					}
					break;
				case "/minecraft:particle":
				case "/particle":
					if (arr.length >= 10
							&& Double.parseDouble(arr[9]) > 10) {
						arr[9] = "10";
						return String.join(" ", arr);
					}
					break;
				case "/minecraft:spreadplayers":
				case "/spreadplayers":
					if (arr.length == 7 && arr[6].contains("@")) {
						return "cancel";
					} else if (arr.length >= 5) {
						if (Double.parseDouble(arr[3]) > 0) {
							arr[3] = "0";
						}
						if (Double.parseDouble(arr[4]) < 8) {
							arr[4] = "8";
						}
						if (Double.parseDouble(arr[4]) > 50) {
							arr[4] = "50";
						}
						return String.join(" ", arr);
					}
					break;
				case "/minecraft:bossbar":
				case "/minecraft:setblock":
				case "/minecraft:tellraw":
				case "/minecraft:title":
				case "/bossbar":
				case "/setblock":
				case "/tellraw":
				case "/title":
					final String charCommand = parseCharCodes(command);
					if (charCommand.contains("selector")) {
						return "cancel";
					}
					break;
				case "/viaversion:viaver":
				case "/viaversion:viaversion":
				case "/viaversion:vvbukkit":
				case "/viaver":
				case "/viaversion":
				case "/vvbukkit":
					if (arr.length >= 2
							&& "debug".equalsIgnoreCase(arr[1])) {
						return "cancel";
					}
					break;
				default:
					break;
			}
		} catch (NumberFormatException exception) {
			// Do nothing
		}

		if (command.contains("distance")) {
			return command.replace("distance=", "]").replace("\"distance\"=", "]").replace("'distance'=", "]");
		}

		return null;
	}

	@EventHandler
	void onServerCommand(final ServerCommandEvent event) {
		final CommandSender sender = event.getSender();

		if (sender instanceof BlockCommandSender) {
			final CommandBlock commandBlock = (CommandBlock) ((BlockCommandSender) sender).getBlock().getState();

			commandBlock.setCommand("");
			commandBlock.update();
		} else if (sender instanceof CommandMinecart) {
			final CommandMinecart commandMinecart = (CommandMinecart) sender;

			commandMinecart.setCommand("");
		}

		final String command = event.getCommand();
		final boolean isConsoleCommand = true;
		final String checkedCommand = checkCommand(sender, command, isConsoleCommand);

		if (checkedCommand != null) {
			if ("cancel".equals(checkedCommand)) {
				event.setCancelled(true);
			} else {
				event.setCommand(checkedCommand);
			}
		}

		System.out.println("Console command: " + command);
	}

	public static String parseCharCodes(final String input) {
		if (input.contains("\\u")) {
			StringBuilder output = new StringBuilder();
			String[] split = input.split("\\\\u");
			int index = 0;
			for (String item:split) {
				if (index == 0) {
					output.append(item);
				} else {
					String charCode = item.substring(0, 4);
					output.append((char) Integer.parseInt(charCode, 16));
					output.append(item.substring(4));
				}
				index++;
			}
			return output.toString();
		} else {
			return input;
		}
	}
}