var DesktopNotify = (function () {
  var bindUIElements = function () {
    window.addEventListener("load", getPermission);
  };

  var init = function () {
    bindUIElements();
  };

  var getPermission = function () {
    if (window.Notification && Notification.permission !== "granted") {
      Notification.requestPermission(function (status) {
        if (Notification.permission !== status) {
          Notification.permission = status;
        }
      });
    }
  };

  var send = function (message, tag) {
    if (typeof tag == "undefined") {
      tag = "default-notification";
    }

    if (window.Notification && Notification.permission === "granted") {
      new Notification(message, { tag: tag });
    }

    // If the user hasn't told if he wants to be notified or not
    // Note: because of Chrome, we are not sure the permission property
    // is set, therefore it's unsafe to check for the "default" value.
    else if (window.Notification && Notification.permission !== "denied") {
      Notification.requestPermission(function (status) {
        if (Notification.permission !== status) {
          Notification.permission = status;
        }

        if (status === "granted") {
          new Notification(message, { tag: tag });
        }
      });
    }
  };

  return {
    init: init,
    send: send,
    getPermission: getPermission
  };
})();

document.addEventListener(
  "DOMContentLoaded",
  function () {
    DesktopNotify.init();
    DesktopNotify.getPermission();

    var button = document.getElementsByTagName("button")[0];
    button.addEventListener("click", function () {
      DesktopNotify.send("Example Message Here");
    });
  },
  false
);