server/utils/burst-calculator.js

   1 'use strict';
   2
   3 /**
   4  * IMPORTANT: this version differs from client-side calculateBursts() due to backbone access methods!
   5  * calculateBursts() calculates what chat messages are 'bursts'.
   6  *
   7  * `Array` chats - the collection of chat messages
   8  * returns the modified chats array
   9  */
  10 var calculateBursts = function(chats) {
  11   // console.time('calculateBursts'); // benchmarking
  12   /* @const - time window, in which an user can keep adding chat items as part of a initial "burst" */
  13   var BURST_WINDOW = 5 * 60 * 1000; // 5 minutes
  14
  15   var burstUser, burstStart;
  16
  17   chats.forEach(function(chat) {
  18     if (chat.parentId) return; // ignore thread messages for now
  19     var newUser = chat.fromUser && chat.fromUser.username;
  20     var newSentTime = chat.sent;
  21
  22     // if message is a me status
  23     if (chat.status) {
  24       burstUser = null;
  25       chat.burstStart = true;
  26       return;
  27     }
  28
  29     // get the duration since last burst
  30     var durationSinceBurstStart = new Date(newSentTime) - new Date(burstStart);
  31
  32     // if the current user is different or the duration since last burst is larger than 5 minutes we have a new burst
  33     if (newUser !== burstUser || durationSinceBurstStart > BURST_WINDOW) {
  34       burstUser = newUser;
  35       burstStart = newSentTime;
  36       chat.burstStart = true;
  37       return;
  38     }
  39
  40     // most messages won't be a burst
  41     chat.burstStart = false;
  42   });
  43   return chats;
  44   // console.timeEnd('calculateBursts');
  45 };
  46
  47 module.exports = calculateBursts;