git ssb

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const nest = require('depnest')
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const { h } = require('mutant')
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const pull = require('pull-stream')
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const Scroller = require('mutant-scroll')
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const next = require('pull-next-step')
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exports.gives = nest('app.html.scroller')
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exports.needs = nest({
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  'message.html.render': 'first'
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})
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exports.create = function (api) {
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  return nest('app.html.scroller', createScroller)
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  function createScroller (opts = {}) {
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    const { 
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      stream,
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      filter = () => pull.filter((msg) => true),
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    } = opts
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    const streamToTop = pull(
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      next(stream, {old: false, limit: 100, property: ['value', 'timestamp']}),
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      filter() // is a pull-stream through
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    )
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    const streamToBottom = pull(
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      next(stream, {reverse: true, limit: 100, live: false, property: ['value', 'timestamp']}),
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      filter()
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    )
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    return Scroller(Object.assign({}, opts, { streamToTop, streamToBottom }))
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    // valid Scroller opts :  see github.com/mixmix/mutant-scroll
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    //   classList = [],
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    //   prepend = [],
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    //   append = [],
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    //   streamToTop,
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    //   streamToBottom,
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    //   render,
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    //   updateTop =  updateTopDefault,
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    //   updateBottom = updateBottomDefault,
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    //   store = MutantArray(),
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    //   cb = (err) => { if (err) throw err }
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  }
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}
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function keyscroll (content) {
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  var curMsgEl
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  if (!content) return () => {}
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  content.addEventListener('click', onActivateChild, false)
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  content.addEventListener('focus', onActivateChild, true)
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  function onActivateChild (ev) {
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    for (var el = ev.target; el; el = el.parentNode) {
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      if (el.parentNode === content) {
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        curMsgEl = el
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        return
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      }
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    }
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  }
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  function selectChild (el) {
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    if (!el) { return }
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    ;(el.scrollIntoViewIfNeeded || el.scrollIntoView).call(el)
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    el.focus()
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    curMsgEl = el
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  }
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  return function scroll (d) {
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    selectChild((!curMsgEl || d === 'first') ? content.firstChild
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      : d < 0 ? curMsgEl.previousElementSibling || content.firstChild
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      : d > 0 ? curMsgEl.nextElementSibling || content.lastChild
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      : curMsgEl)
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    return curMsgEl
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  }
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}
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