/**
 * Create a new cookie.
 *
 * @param {string} name The cookie name.
 * @param {*} value The cookie value.
 * @param {number} days The expiration, in days.
 * @return {void}
 */
window.wu_create_cookie = function(name, value, days) {

  let expires;

  if (days) {

    const date = new Date();

    date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));

    expires = '; expires=' + date.toGMTString();

  } else {

    expires = '';

  } // end if;

  document.cookie = name + '=' + value + expires + '; path=/';

};

/**
 * Reads from a cookie.
 *
 * @param {string} name The cookie name
 * @return {*} The cookie value
 */
window.wu_read_cookie = function(name) {

  const nameEQ = name + '=';

  const ca = document.cookie.split(';');

  for (let i = 0; i < ca.length; i++) {

    let c = ca[i];

    while (c.charAt(0) === ' ') {

      c = c.substring(1, c.length);

    } // end while;

    if (c.indexOf(nameEQ) === 0) {

      return c.substring(nameEQ.length, c.length);

    } // end if;

  } // end for;

  return null;

};

/**
 * Erase a cookie.
 *
 * @param {string} name The cookie name.
 */
window.wu_erase_cookie = function(name) {

  window.wu_create_cookie(name, '', -1);

};

/**
 * Listens to a particular cookie to catch a change in value.
 *
 * @param {string} name The cookie name.
 * @param {Function} callback The callback to call when a change is detected.
 */
window.wu_listen_to_cookie_change = function(name, callback) {

  let cookie_value = window.wu_read_cookie(name);

  setInterval(function() {

    const new_cookie_value = window.wu_read_cookie(name);

    if (new_cookie_value !== cookie_value) {

      // update registry so we dont get triggered again
      cookie_value = new_cookie_value;

      callback(cookie_value);

    } // end if;

  }, 100);

};