git ssb

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const pull = require('pull-stream')
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const { isBlob } = require('ssb-ref')
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module.exports = function (server) {
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  if (!server) throw new Error('day-posts helper requires a server!')
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  if (!server.query) throw new Error('day-posts helper requires a server with the ssb-query installed!')
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  return function getAvatar (feedId, cb) {
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    // NOTE the data is coming in from the dayPosts source and has been mapped into the form { author, timestamp, text, root }
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    // cb is a function provided to us by pull-paramap which we use to pass results out once we're done and to pass things on to the next part of the stream (the collect here)
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    const opts = {
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      reverse: true,
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      query: [
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        {
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          $filter: {
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            value: {
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              author: feedId,
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              content: {
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                type: 'about',
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                about: feedId,
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                image: { $truthy: true }
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              },
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              timestamp: { $gt: 0 } // a hack that forces ordering by timestamp
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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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            image: ['value', 'content', 'image']
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          }
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        }
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      ]
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    }
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    pull(
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      server.query.read(opts),
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      // hooray the format for image about is non-standardised... could be image.link or image that the blob link is stored under
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      pull.map(data => typeof data.image === 'string'
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        ? data.image
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        : data.image.link
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      ),
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      pull.filter(link => isBlob(link)),
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      pull.take(1),
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      pull.collect((err, results) => {
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        if (err) {
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          cb(err)
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          return
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        }
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        if (!results || !results.length) cb(null, null)
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        else cb(null, results[0])
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      })
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    )
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  }
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}
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