!async function(w, document, host) {
  // look for bots, bail out of fishy userAgent
  if (w.navigator.userAgent.search(/(bot|spider|crawl|preview)/gi) > -1) {
    return
  }

  let event
  let session

  const get = async (url) => {
    let r = await fetch(url)
    return await r.text()
  }

  const cache = async () => {
    return get(`${host}/cache`)
  }
  session = await cache()

  const params = data =>
    Object.keys(data)
      .map(key => `${key}=${encodeURIComponent(data[key])}`)
      .join('&')

  const send = async (type, data) => {
    let url = `${host}/ping?t=${type}&${params(data)}&p=${event}&s=urn:uuid:${session}`
    return await get(url)
  }

  const getData = (node) => node
    .getAttributeNames()
    .filter(ns => ns.startsWith('pb:') || ns === 'url')
    .reduce((o, key) => ({ ...o, [key]: node.getAttribute(key)}), {})

  const pageview = async (node) => {
    event = await send('View', getData(node))
  }

  const checkNode = document => {
    document
      .querySelectorAll('push-broom')
      .forEach(node => {
        pageview(node)
      })
  }

  const domchange = (arr) => {
    checkNode(document)
  }
  const dom = new MutationObserver(domchange)
  dom.observe(document.body, {subtree: true, childList: true})
  checkNode(document)

}(window, document, "https://pushbroom.co")