util.ts

/**
 * MTKruto - Cross-runtime JavaScript library for building Telegram clients
 * Copyright (C) 2023-2024 Roj <https://roj.im/>
 *
 * This file is part of MTKruto.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

function isAlpha(string: string) {
  const c = string.charCodeAt(0) | 0x20;
  return "a".charCodeAt(0) <= c && c <= "z".charCodeAt(0);
}
function isDigit(string: string) {
  const c = string.charCodeAt(0);
  return "0".charCodeAt(0) <= c && c <= "9".charCodeAt(0);
}
const errInvalidUsername = (u: string) => new Error(`Invalid username: ${u}`);
function validateUsername(string: string, ignoreAt = false) {
  string = string.trim();
  if (ignoreAt && string.startsWith("@")) {
    string = string.slice(1);
  }
  if (string.length == 0 || string.length > 32) {
    throw errInvalidUsername(string);
  }
  if (!isAlpha(string[0])) {
    throw errInvalidUsername(string);
  }
  for (const c of string) {
    if (!isAlpha(c) && !isDigit(c) && c != "_") {
      throw errInvalidUsername(string);
    }
  }
  if (string[string.length - 1] == "_") {
    throw errInvalidUsername(string);
  }
  for (let i = 1; i < string.length; ++i) {
    if (string[i - 1] == "_" && string[i] == "_") {
      throw errInvalidUsername(string);
    }
  }

  return string;
}
export function getUsername(string: string) {
  let url: URL | null = null;
  try {
    url = new URL(string);
  } catch {
    try {
      url = new URL("https://" + string);
    } catch {
      //
    }
  }
  if (url === null || (url.protocol != "http:" && url.protocol != "https:")) {
    return validateUsername(string, true);
  }
  if (
    url.hostname != "telegram.dog" && url.hostname != "telegram.me" &&
    url.hostname != "t.me" && !url.hostname.endsWith(".t.me")
  ) {
    return validateUsername(string, true);
  }
  if (
    url.hostname == "telegram.dog" || url.hostname == "telegram.me" ||
    url.hostname == "t.me"
  ) {
    return validateUsername(url.pathname.split("/")[1]);
  }
  const parts = url.hostname.split(".");
  if (parts.length != 3) {
    return validateUsername(string);
  }
  return validateUsername(parts[0]);
}