semaphore/routes/_components/timeline/Timeline.html

<div class="timeline" role="feed" aria-label="{{label}}">
  {{#if virtual}}
    <VirtualList component="{{StatusVirtualListItem}}"
                 :makeProps
                 items="{{$statusIds}}"
                 on:scrollToBottom="onScrollToBottom()"
                 shown="{{$initialized}}"
                 footerComponent="{{LoadingFooter}}"
                 showFooter="{{$initialized && $runningUpdate}}"
                 realm="{{$currentInstance + '/' + timeline}}"
                 on:initializedVisibleItems="initialize()"
    />
  {{else}}
    <!-- if this is a status thread, it's easier to just render the
         whole thing rather than use a virtual list -->
    <PseudoVirtualList component="{{StatusVirtualListItem}}"
                       :makeProps
                       items="{{$statusIds}}"
                       shown="{{$initialized}}"
                       on:initializedVisibleItems="initialize()"
                       scrollToItem="{{timelineValue}}"
                       realm="{{$currentInstance + '/' + timeline}}"
    />
  {{/if}}
</div>
<style>
  .timeline {
    min-height: 60vh;
  }
</style>
<script>
  import { store } from '../../_store/store'
  import StatusVirtualListItem from './StatusVirtualListItem.html'
  import Status from '../status/Status.html'
  import PseudoVirtualList from '../pseudoVirtualList/PseudoVirtualList.html'
  import LoadingFooter from './LoadingFooter.html'
  import VirtualList from '../virtualList/VirtualList.html'
  import { timelines } from '../../_static/timelines'
  import { database } from '../../_utils/database/database'
  import { initializeTimeline, fetchStatusesOnScrollToBottom, setupTimeline } from '../../_actions/timeline'

  export default {
    async oncreate() {
      console.log('timeline oncreate()')
      setupTimeline()
    },
    data: () => ({
      StatusVirtualListItem,
      LoadingFooter,
      Status
    }),
    computed: {
      makeProps: ($currentInstance, timelineType, timelineValue) => async (statusId) => ({
        timelineType: timelineType,
        timelineValue: timelineValue,
        status: await database.getStatus($currentInstance, statusId)
      }),
      label: (timeline, $currentInstance, timelineType, timelineValue) => {
        if (timelines[timeline]) {
          return `${timelines[timeline].label} timeline for ${$currentInstance}`
        }

        switch (timelineType) {
          case 'tag':
            return `#${timelineValue} timeline for ${$currentInstance}`
          case 'status':
            return 'Status context'
          case 'account':
            return `Account #${timelineValue} on ${$currentInstance}`
        }
      },
      timelineType: (timeline) => {
        return timeline.split('/')[0]
      },
      timelineValue: (timeline) => {
        return timeline.split('/').slice(-1)[0]
      },
      // for threads, it's simpler to just render all items due to need to scroll to the right item
      // TODO: this can be optimized to use a virtual list
      virtual: (timelineType) => timelineType !=='status'
    },
    store: () => store,
    components: {
      VirtualList,
      PseudoVirtualList
    },
    methods: {
      initialize() {
        if (this.store.get('initialized') || !this.store.get('statusIds') || !this.store.get('statusIds').length) {
          return
        }
        console.log('timeline initialize()')
        initializeTimeline()
      },
      onScrollToBottom() {
        if (!this.store.get('initialized') ||
            this.store.get('runningUpdate') ||
            this.get('timelineType') === 'status') { // for status contexts, we've already fetched the whole thread
          return
        }
        fetchStatusesOnScrollToBottom()
      }
    }
  }
</script>