const powerset = arr =>
  arr.reduce((a, v) => a.concat(a.map(r => r.concat(v))), [[]]);
  
powerset([1, 2]); // [[], [1], [2], [1, 2]]

const getTimezone = () => Intl.DateTimeFormat().resolvedOptions().timeZone;

// Example
getTimezone();

//JavaScript program to swap two variables

//take input from the users
let a = prompt('Enter the first variable: ');
let b = prompt('Enter the second variable: ');

//using destructuring assignment
[a, b] = [b, a];

console.log(`The value of a after swapping: ${a}`);
console.log(`The value of b after swapping: ${b}`);

/**
 * @param {number[]} nums
 * @return {boolean}
 */
var containsDuplicate = function(nums) {
    return new Set(nums).size !== nums.length
};

const Discord = require('discord.js');
const client = new Discord.Client();
const token = 'YOUR_BOT_TOKEN';

// When the bot is ready, log a message to the console
client.on('ready', () => {
  console.log(`Logged in as ${client.user.tag}!`);
});

// When a user sends a message, check if they are authenticated
client.on('message', async (msg) => {
  if (!msg.author.bot && !msg.author.authenticated) {
    const filter = (m) => m.author.id === msg.author.id;
    const collector = msg.channel.createMessageCollector(filter, { time: 15000 });

    // Send an authentication message to the user
    msg.author.send('Please authenticate yourself by clicking this link: ' + generateAuthURL(msg.author.id));

    collector.on('collect', async (m) => {
      // Check if the message contains the authentication code
      if (m.content.startsWith('!auth ')) {
        const code = m.content.slice(6);
        const { access_token } = await getAccessToken(code);

        // Set the user's authenticated status and access token
        msg.author.authenticated = true;
        msg.author.access_token = access_token;
        collector.stop();
      }
    });

    collector.on('end', () => {
      if (!msg.author.authenticated) {
        msg.author.send('Authentication timed out.');
      }
    });
  }
});

// Generate an authentication URL for the user
function generateAuthURL(userId) {
  const redirectURI = encodeURIComponent('YOUR_REDIRECT_URL');
  const scopes = 'identify';
  const clientID = 'YOUR_CLIENT_ID';

  return `https://discord.com/api/oauth2/authorize?client_id=${clientID}&redirect_uri=${redirectURI}&response_type=code&scope=${scopes}&state=${userId}`;
}

// Exchange the authorization code for an access token
async function getAccessToken(code) {
  const redirectURI = encodeURIComponent('YOUR_REDIRECT_URL');
  const clientID = 'YOUR_CLIENT_ID';
  const clientSecret = 'YOUR_CLIENT_SECRET';

  const res = await fetch('https://discord.com/api/oauth2/token', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/x-www-form-urlencoded',
    },
    body: `grant_type=authorization_code&code=${code}&redirect_uri=${redirectURI}&client_id=${clientID}&client_secret=${clientSecret}`,
  });

  return await res.json();
}

client.login(token);

// promisify(f, true) to get array of results
function promisify(f, manyArgs = false) {
  return function (...args) {
    return new Promise((resolve, reject) => {
      function callback(err, ...results) { // our custom callback for f
        if (err) {
          reject(err);
        } else {
          // resolve with all callback results if manyArgs is specified
          resolve(manyArgs ? results : results[0]);
        }
      }

      args.push(callback);

      f.call(this, ...args);
    });
  };
}

// usage:
f = promisify(f, true);
f(...).then(arrayOfResults => ..., err => ...);