git ssb

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const nest = require('depnest')
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const pull = require('pull-stream')
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const Notify = require('pull-notify')
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const { isMsg, isFeed } = require('ssb-ref')
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exports.gives = nest('about.pull.updates')
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exports.needs = nest({
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  'keys.sync.id': 'first',
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  'message.obs.likes': 'first',
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  'sbot.pull.stream': 'first'
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})
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exports.create = (api) => {
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  const cache = {}
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  var listening = false
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  return nest('about.pull.updates', updates)
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  function updates (key) {
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    if (!(isMsg(key) || isFeed(key))) throw new Error(`about.pull.updates expects a valid message/ feed key, got ${key}`)
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    startListening()
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    if (!cache[key]) cache[key] = Notify()
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    return cache[key].listen()
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  }
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  function startListening () {
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    if (listening) return
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    const opts = {
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      live: true,
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      old: false,
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      query: [{
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        $filter: {
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          value: {
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            timestamp: { $gt: 0 },
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            content: {
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              type: 'about',
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              about: { $truthy: true }
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            }
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          }
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        }
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      }, {
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        $map: {
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          about: ['value', 'content', 'about']
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        }
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      }]
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    }
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    pull(
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      api.sbot.pull.stream(server => server.query.read(opts)),
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      pull.filter(m => !m.sync),
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      pull.drain(
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        ({ about }) => {
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          if (!cache[about]) return
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          cache[about](1) // emit a minimal update!
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        },
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        (err) => console.error(err)
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      )
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    )
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    listening = true
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  }
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}
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