'use strict';
const crypto = require('crypto');

function getCredentials(name, secret) {
  // this credential would be valid for the next 24 hours
  const timestamp = parseInt(Date.now() / 1000, 10) + 24 * 3600;
  const username = [timestamp, name].join(':');
  const hmac = crypto.createHmac('sha1', secret);
  hmac.setEncoding('base64');
  hmac.write(username);
  hmac.end();
  const credential = hmac.read();
  return { username, credential };
}

function processServers(iceServers) {
  return iceServers.map(server => {
    switch (server.auth) {
      case undefined:
        return server;
      case 'secret':
        const cred = getCredentials(server.username, server.secret);
        return {
          url: server.url,
          urls: server.urls,
          username: cred.username,
          credential: cred.credential
        };
      default:
        throw new Error('Authentication type not implemented: ' + server.auth);
    }
  });
}

module.exports = { getCredentials, processServers };