1  const MAX_UPDATES = 20
 2  
 3  function aggregateSampleStats(target, newData) {
 4    target.viewers += newData.viewers
 5    target.bits += newData.bits
 6    target.chatters += newData.chatters
 7    target.messages += newData.messages
 8    target.questions += newData.questions
 9  }
10  
11  function makeUpdateMessage(begin, resolve, sample, live, lead) {
12    const message = { type: "UPDATE" }
13  
14    message.data = {
15      lead: Object.fromEntries(lead),
16      sample: Object.fromEntries(sample),
17      live: Array.from(live.entries()),
18      resolve: Object.fromEntries(resolve),
19      begin: Object.fromEntries(begin)
20    }
21    
22    return JSON.stringify(message)
23  }
24  
25  export function MakeRealTimeUpdates(ws) {
26    const scheduledUpdates = new Map()
27    const sample = new Map()
28    const begin = new Map()
29    const live = new Map()
30    const lead = new Map()
31    const resolve = new Map()
32  
33    let updateCount = 0
34  
35    function buffer({ type, data }) {
36      switch (type) {
37        case "lead": {
38          lead.set(data.$userName, data)
39          break
40        }
41        case "begin": {
42          const { sample } = data
43          begin.set(sample.userName, sample)
44          break
45        } 
46        case "resolve": {
47          const { userName, status } = data
48          resolve.set(userName, status)
49          break
50        }
51        case "sample": {
52          const { userName } = data
53          if (!sample.has(userName)) {
54            sample.set(userName, data)
55          } else {
56            aggregateSampleStats(sample.get(userName), data)
57          }
58          break
59        }
60        case "live": {
61          live.clear()
62          for (const [userName, channelId] of data.entries()) {
63            live.set(userName, channelId)
64          }
65          break
66        }
67        default: {}
68      }
69  
70      if (++updateCount > MAX_UPDATES) {   
71        ws.publish("updates", makeUpdateMessage(begin, resolve, sample, live, lead))
72  
73        resolve.clear()
74        sample.clear()
75        begin.clear()
76        lead.clear()
77        
78        updateCount = 0
79      }
80    }
81  
82    return {
83      buffer, 
84      async schedule(type, interval, dataFn) {
85        const cb = async () => {
86          const data = await dataFn()
87          buffer({ type, data })
88        }
89        await cb() // perform scheduled update immediately
90        scheduledUpdates.set(type, setInterval(async () => { await cb() }, interval))
91      },
92      unschedule(id) {
93        clearInterval(scheduledUpdates.get(id))
94        scheduledUpdates.delete(id)
95      }
96    }
97  }