360 lines
12 KiB
TypeScript
360 lines
12 KiB
TypeScript
import * as Cookies from "js-cookie";
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import {Commands} from "./Commands";
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import {Environment} from "./Environment";
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import {Directory, File, FileSystem, Node, Path} from "./FileSystem";
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import {InputParser} from "./InputParser";
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import {asciiHeaderHtml, IllegalStateError, stripHtmlTags} from "./Shared";
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import {EscapeCharacters, InputHistory} from "./Terminal";
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import {UserList} from "./UserList";
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/**
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* A shell that interacts with the user session and file system to execute commands.
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*/
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export class Shell {
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/**
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* The environment in which commands are executed.
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*/
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private readonly environment: Environment;
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/**
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* The history of the user's inputs.
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*/
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private readonly inputHistory: InputHistory;
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/**
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* The user session describing the user that interacts with the shell.
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*/
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private readonly userList: UserList;
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/**
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* The file system.
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*/
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private readonly fileSystem: FileSystem;
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/**
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* The set of commands that can be executed.
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*/
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private readonly commands: Commands;
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/**
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* The name of the user that the user is currently trying to log in as, or `undefined` if the user is not currently
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* trying to log in.
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*/
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private attemptUser: string | undefined;
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/**
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* Constructs a new shell.
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*
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* @param inputHistory the history of inputs
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*/
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constructor(inputHistory: InputHistory) {
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this.inputHistory = inputHistory;
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this.userList = new UserList();
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this.fileSystem = Shell.loadFileSystem();
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this.environment = Shell.loadEnvironment(this.fileSystem, this.userList);
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this.commands = new Commands(this.environment, this.userList, this.fileSystem);
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this.saveState();
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}
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/**
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* Returns the header that is displayed when a user logs in.
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*/
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generateHeader(): string {
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if (this.environment.get("user") === "")
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return "";
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return `${asciiHeaderHtml}
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Student MSc Computer Science <span class="smallScreenOnly">
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</span>@ <a href="https://www.tudelft.nl/en/">TU Delft</a>, the Netherlands
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<span class="wideScreenOnly">${(new Date()).toISOString()}
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</span>
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Type "<a href="#" onclick="execute('help');">help</a>" for help.
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`.trimLines();
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}
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/**
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* Returns the prefix based on the current state of the terminal.
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*/
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generatePrefix(): string {
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const userName = this.environment.get("user");
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if (userName === "") {
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return this.attemptUser === undefined
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? "login as: "
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: `Password for ${this.attemptUser}@fwdekker.com: `;
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}
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const cwd = new Path(this.environment.get("cwd"));
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const link = cwd.ancestors.reverse()
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.concat(cwd)
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.map(part => this.fileSystem.get(part)?.nameString(part.fileName + "/", part)).join("");
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return `${userName}@fwdekker.com <span class="prefixPath">${link}</span>> `;
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}
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/**
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* Processes a user's input.
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*
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* @param inputString the input to process
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*/
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execute(inputString: string): string {
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if (this.environment.get("user") === "") {
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if (this.attemptUser === undefined) {
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this.attemptUser = inputString.trim() ?? undefined; // Set to undefined if empty string
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this.saveState();
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return EscapeCharacters.Escape + EscapeCharacters.HideInput;
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} else {
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const attemptUser = this.userList.get(this.attemptUser);
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let resultString: string;
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if (attemptUser !== undefined && attemptUser.password === inputString) {
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this.environment.set("user", this.attemptUser);
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resultString = this.generateHeader();
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} else {
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resultString = "Access denied\n";
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}
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this.attemptUser = undefined;
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this.saveState();
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return EscapeCharacters.Escape + EscapeCharacters.ShowInput + resultString;
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}
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}
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this.inputHistory.addEntry(inputString.trim());
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const parser = InputParser.create(this.environment, this.fileSystem);
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let input;
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try {
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input = parser.parse(stripHtmlTags(inputString));
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} catch (error) {
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return error.message;
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}
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if (input.redirectTarget[0] === "write") {
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try {
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const path = Path.interpret(this.environment.get("cwd"), input.redirectTarget[1]);
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this.fileSystem.remove(path, true, false, false);
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} catch (error) {
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return error.message;
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}
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}
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let output = this.commands.execute(input);
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if (input.redirectTarget[0] !== "default") {
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const path = Path.interpret(this.environment.get("cwd"), input.redirectTarget[1]);
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output = this.writeToFile(path, output, input.redirectTarget[0] === "append");
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}
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if (this.environment.get("user") === "") {
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this.inputHistory.clear();
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this.environment.clear();
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this.environment.set("cwd", "/");
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this.environment.set("user", "");
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}
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this.saveState();
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return input.redirectTarget[0] === "default" ? output : "";
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}
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/**
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* Writes or appends `data` to `file`.
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*
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* @param path the path of the file to write or append to
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* @param data the data to write or append
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* @param append `true` if and only if the data should be appended
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*/
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private writeToFile(path: Path, data: string, append: boolean): string {
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try {
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this.fileSystem.add(path, new File(), true);
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} catch (error) {
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return error.message;
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}
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const target = this.fileSystem.get(path);
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if (!(target instanceof File))
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throw new IllegalStateError("File unexpectedly disappeared since last check.");
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if (append)
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target.contents += data;
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else
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target.contents = data;
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return "";
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}
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/**
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* Saves the shell's state in cookies.
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*/
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private saveState() {
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Cookies.set("files", this.fileSystem.root, {
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"expires": new Date(new Date().setFullYear(new Date().getFullYear() + 25)),
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"path": "/"
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});
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Cookies.set("env", this.environment.variables, {"path": "/"});
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}
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/**
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* Returns the file system loaded from a cookie, or the default file system if no cookie is present or the cookie
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* is invalid.
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*/
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private static loadFileSystem(): FileSystem {
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let files: Directory | undefined = undefined;
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const filesString = Cookies.get("files");
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if (filesString !== undefined) {
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try {
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const parsedFiles = Node.deserialize(filesString);
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if (parsedFiles instanceof Directory)
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files = parsedFiles;
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else
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console.warn("`files` cookie contains non-directory.");
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} catch (error) {
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console.warn("Failed to deserialize `files` cookie.", error);
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}
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}
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return new FileSystem(files);
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}
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/**
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* Returns the environment loaded from a cookie, or the default environment if no cookie is present or the cookie
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* is invalid.
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*
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* @param fileSystem the file system used to validate the `cwd` environment variable
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* @param userList the list of users used to validate the `user` environment variable
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*/
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private static loadEnvironment(fileSystem: FileSystem, userList: UserList): Environment {
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const environmentString = Cookies.get("env") ?? "{}";
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let environment: Environment;
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try {
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environment = new Environment(["cwd", "user"], JSON.parse(environmentString));
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} catch (error) {
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console.warn("Failed to set environment from cookie.");
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environment = new Environment(["cwd", "user"]);
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}
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// Check cwd in environment
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if (!environment.has("cwd")) {
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environment.set("cwd", "/");
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} else if (!fileSystem.has(new Path(environment.get("cwd")))) {
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console.warn(`Invalid cwd '${environment.get("cwd")}' in environment.`);
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environment.set("cwd", "/");
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}
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// Check user in environment
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if (!environment.has("user")) {
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environment.set("user", "felix");
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} else if (environment.get("user") !== "" && !userList.has(environment.get("user"))) {
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console.warn(`Invalid user '${environment.get("user")}' in environment.`);
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environment.set("user", "felix");
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}
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return environment;
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}
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}
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export module InputArgs {
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/**
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* The options given to a command.
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*/
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export type Options = { [key: string]: string | null };
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/**
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* The intended target of the output of a command.
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*
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* <ul>
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* <li>`default` means that the output should be written to the standard output</li>
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* <li>`write` means that the output should be written to the file in the given string</li>
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* <li>`append` means that the output should be appended to the file in the given string</li>
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* </ul>
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*/
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export type RedirectTarget = ["default"] | ["write" | "append", string];
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}
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/**
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* A set of parsed command-line arguments.
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*/
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export class InputArgs {
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/**
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* The name of the command, i.e. the first token in the input string.
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*/
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readonly command: string;
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/**
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* The set of options and the corresponding values that the user has given.
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*/
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private readonly _options: InputArgs.Options;
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/**
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* The remaining non-option arguments that the user has given.
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*/
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private readonly _args: string[];
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/**
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* The target of the output stream.
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*/
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readonly redirectTarget: InputArgs.RedirectTarget;
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/**
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* Constructs a new set of parsed command-line arguments.
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*
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* @param command the name of the command, i.e. the first token in the input string
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* @param options the set of options and the corresponding values that the user has given
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* @param args the remaining non-option arguments that the user has given
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* @param redirectTarget the target of the output stream
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*/
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constructor(command: string, options: InputArgs.Options, args: string[], redirectTarget: InputArgs.RedirectTarget) {
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this.command = command;
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this._options = options;
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this._args = args;
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this.redirectTarget = redirectTarget;
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}
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/**
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* Returns a copy of the options the user has given.
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*/
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get options(): InputArgs.Options {
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return Object.assign({}, this._options);
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}
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/**
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* Returns `true` if and only if the option with the given key has been set.
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*
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* @param key the key to check
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*/
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hasOption(key: string): boolean {
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return this._options.hasOwnProperty(key);
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}
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/**
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* Returns `true` if and only if at least one of the options with the given keys has been set.
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*
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* @param keys the keys to check
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*/
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hasAnyOption(keys: string[]): boolean {
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for (let i = 0; i < keys.length; i++)
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if (this.hasOption(keys[i]))
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return true;
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return false;
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}
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/**
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* Returns a copy of the arguments the user has given.
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*/
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get args(): string[] {
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return this._args.slice();
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}
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/**
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* Returns `true` if and only if there is an argument at the given index.
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*
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* @param index the index to check
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*/
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hasArg(index: number): boolean {
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return this._args[index] !== undefined;
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}
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}
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