AccountSwitcher.js

const WidgetManager = Java.type('org.openosrs.api.WidgetManager');
const ScriptAPI = Java.type('org.openosrs.api.ScriptAPI');
const File = Java.type('java.io.File');
const FileReader = Java.type('java.io.FileReader');
const FileWriter = Java.type('java.io.FileWriter');
const JsonReader = Java.type('com.google.gson.JsonReader');
const JsonWriter = Java.type('com.google.gson.JsonWriter');

const FILE_NAME = 'accounts.json';

// Initiate plugin
function init() {
  const settingsWidget = WidgetManager.createWidget(50, 50);
  settingsWidget.setHidden(true);

  createSettingsMenu(settingsWidget);
  createLoginMenu(settingsWidget);

  loadAccounts();
}

function createSettingsMenu(settingsWidget) {
  // create UI for adding and removing accounts
}

function createLoginMenu(settingsWidget) {
  // create UI for logging in with an existing account
}

function addAccount(account) {
  // add a new account to the JSON file
}

function removeAccount(account) {
  // remove an account from the JSON file
}

function loadAccounts() {
  // load existing accounts from the JSON file
}

function saveAccounts() {
  // save the current list of accounts to the JSON file
}

function login(username, password) {
  // log in to the game with the provided username and password
}