userscript that displays web notifications for new conversations (almost) live

newconversations.user.js

// ==UserScript==
// @name New Conversation Notifier (Beta!)
// @version 1.0.0
// @description Notifies you about new conversations live on powdertoy.co.uk
// @author boxmein
// @match *://powdertoy.co.uk/*
// ==/UserScript==

/*
  1.0.0 : Sun Nov 30 2014 17:39:06 GMT+0200 (FLE Standard Time)
*/

(function() {
  'use strict';

  function contentEval(source) {

    // We want web notification permissions!
    Notification.requestPermission(function (status) {
      // This allows to use Notification.permission with Chrome/Safari
      if (Notification.permission !== status) {
        Notification.permission = status;
      }
    });

    // Check for function input.
    if ('function' == typeof source) {
      // Execute this function with no arguments, by adding parentheses.
      // One set around the function, required for valid syntax, and a
      // second empty set calls the surrounded function.
      source = '(' + source + ')();'
    }

    // Create a script node holding this  source code.
    var script = document.createElement('script');
    script.setAttribute("type", "application/javascript");
    script.textContent = source;

    // Insert the script node into the page, so it will run, and immediately
    // remove it to clean up.
    document.body.appendChild(script);
    document.body.removeChild(script);
  }

  contentEval(function() {

    // 5 minutes
    var DELAY = 1000 * 60 * 5;

    // Parse the unread conversation's DOM element.
    // Fetch the actual message while at it.
    function parseNotificationElement(d) {

      var deferred = new $.Deferred();

      var subjectLink = d.querySelector('.Subject');
      var metadata = d.querySelector('.Meta');
      var convid = subjectLink.href.match(/[0-9]+$/)[0];

      var endobj = {
        'subject': subjectLink.innerText,
        'convid': convid,
        'author': metadata.querySelector('.LastUsername').innerText,
        'date': metadata.querySelector('.LastDate').innerText
      };
      
      $.ajax('/Conversations/View.json?ConvID='+convid,{
        'dataType': 'html'
      }).done(function(data){

        var div = document.createElement('div');
        div.innerHTML = data;

        var post = div.querySelector('.MessageList .Post');

        endobj.avatar = post.querySelector('.gravatar-inner img').src;
        endobj.message = post.querySelector('.Message').innerText;

        deferred.resolve(endobj);
      }).fail(deferred.reject);

      return deferred;
    }



    // Display a notification if the user is not logged in.
    function userNotLoggedIn(msg) {
      if (Notification.permission == 'granted') {
        var n = new Notification("You seem to not be logged in!", {
          body: msg
        });
      }
      else {
        alert('You seem to not be logged in!\n' + msg); 
      }
     }



    // Get unread messages from /Conversations.json's partial HTML 
    function getUnreads() {

      $.ajax('/Conversations.json',{
        'dataType': 'html'
      }).done(function(data) {
        var d = document.createElement('div');
        d.innerHTML = data;

        if (d.querySelector('.Warning.alert'))
          userNotLoggedIn(d.querySelector('.Warning.alert').innerText);

        var ds = d.getElementsByClassName('ConUnread'); 

        if (ds.length > 1) {
          
          // display a list notification
          ds = ds.map(parseNotificationElement);

          displayListNotification(ds);
        }
        else if (ds.length == 1) 
          parseNotificationElement(ds[0])
                  .done(displayNotification);
        else return;   
          

      }).fail(function() {
        console.error('failed to check for unread messages', arguments);
      });
    }



    // Display a web notification with the unread message
    function displayNotification(data) {
      if (Notification.permission == 'granted') {
        // Use web notifications API
        var n = new Notification("New Conversation: " + data.subject, {
          body: data.message,
          icon: data.avatar
        });
        
        // yay click events!
        n.onclick = function() {
          window.location = '/Conversations/View.html?ConvID='+data.convid;
        };
      }
      else {
        if (confirm('New Conversation: ' + data.subject + ', click Confirm to view')){
          window.location = '/Conversations/View.html?ConvID='+data.convid;
        }
      }
    }

    // Display a notification for a bunch of new conversations at once.
    function displayListNotification(datas) {
      var messages = datas.reduce(function(acc, each) {
                       return acc + '\n' + each.message;
                     }, "");

      if (Notification.permission == 'granted') {
        var n = new Notification('New Conversations (' + datas.length + ')', {
          'body': messages
        });
      } else {
        alert('New Conversations ('+datas.length+')\n'+messages);
      }
    }

    // Check for messages right at the start, and then forever onward, 5 minutes
    // at a time.
    (function tick() {
      getUnreads();
      setTimeout(tick, DELAY);
    })(); 
  });
})();