git ssb

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const shortFeedId = require('./sync.js')
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const { computed } = require('mutant')
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const nest = require('depnest')
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const ref = require('ssb-ref')
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const colorHash = new (require('color-hash'))()
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const fallbackImageUrl = 'data:image/gif;base64,R0lGODlhAQABAPAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw=='
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const MutantPullValue = require('../../mutant-pull-value')
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const MutantPullDict = require('../../mutant-pull-dict')
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exports.needs = nest({
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  'sbot.pull.stream': 'first',
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  'blob.sync.url': 'first'
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})
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exports.gives = nest({
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  'about.obs': [
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    'name',
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    'description',
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    'image',
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    'imageUrl',
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    'names',
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    'images',
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    'color',
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    'latestValue',
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    'valueFrom',
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    'socialValue',
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    'groupedValues',
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    'socialValues'
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  ]
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})
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exports.create = function (api) {
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  const socialValueCache = {}
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  return nest({
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    'about.obs': {
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      // quick helpers, probably should deprecate!
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      name: (id) => socialValue(id, 'name', shortFeedId(id)),
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      description: (id) => socialValue(id, 'description'),
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      image: (id) => socialValue(id, 'image'),
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      names: (id) => groupedValues(id, 'name'),
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      images: (id) => groupedValues(id, 'image'),
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      color: (id) => computed(id, (id) => colorHash.hex(id)),
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      imageUrl: (id) => computed(socialValue(id, 'image'), (blobId) => {
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        return blobId ? api.blob.sync.url(blobId) : fallbackImageUrl
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      }),
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      // custom abouts (the future!)
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      valueFrom,
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      latestValue,
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      socialValue,
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      socialValues,
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      groupedValues
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    }
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  })
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  function valueFrom (id, key, authorId) {
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    if (!ref.isLink(id)) throw new Error('About requires an ssb ref!')
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    return MutantPullValue(() => {
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      return api.sbot.pull.stream((sbot) => sbot.about.latestValueStream({ dest: id, key, authorId }))
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    })
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  }
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  function latestValue (id, key) {
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    if (!ref.isLink(id)) throw new Error('About requires an ssb ref!')
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    return MutantPullValue(() => {
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      return api.sbot.pull.stream((sbot) => sbot.about.latestValueStream({ dest: id, key }))
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    })
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  }
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  function socialValue (id, key, defaultValue) {
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    if (!ref.isLink(id)) throw new Error('About requires an ssb ref!')
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    if (!socialValueCache[id + '/' + key]) {
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      const obs = socialValueCache[id + '/' + key] = MutantPullValue(() => {
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        return api.sbot.pull.stream((sbot) => sbot.about.socialValueStream({ dest: id, key }))
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      }, {
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        onListen: () => { socialValueCache[id + '/' + key] = obs },
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        onUnlisten: () => delete socialValueCache[id + '/' + key]
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      })
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    }
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    return withDefault(socialValueCache[id + '/' + key], defaultValue)
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  }
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  function socialValues (id, key) {
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    if (!ref.isLink(id)) throw new Error('About requires an ssb ref!')
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    return MutantPullDict(() => {
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      return api.sbot.pull.stream((sbot) => sbot.about.socialValuesStream({ dest: id, key }))
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    }, { checkDelete })
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  }
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  function groupedValues (id, key) {
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    if (!ref.isLink(id)) throw new Error('About requires an ssb ref!')
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    return computed(socialValues(id, key), getGroupedValues)
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  }
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}
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function checkDelete (msg) {
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  if (msg && msg.remove) return true
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}
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function getGroupedValues (lookup) {
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  const values = {}
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  for (const author in lookup) {
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    const value = getValue(lookup[author])
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    if (value != null) {
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      values[value] = values[value] || []
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      values[value].push(author)
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    }
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  }
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  return values
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}
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function getValue (item) {
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  if (typeof item === 'string') {
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    return item
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  } else if (item && item.link && ref.isLink(item.link) && !item.remove) {
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    return item.link
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  }
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}
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function withDefault (value, defaultValue) {
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  if (typeof defaultValue === 'undefined') {
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    return value
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  } else {
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    return computed([value, defaultValue], fallback)
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  }
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}
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function fallback (value, defaultValue) {
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  if (value == null) {
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    return defaultValue
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  } else {
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    return value
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  }
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}
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