git ssb

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var pull = require('pull-stream')
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var cat = require('pull-cat')
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var u = require('./util')
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var ref = require('ssb-ref')
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var asyncMemo = require('asyncmemo')
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function mixin(a, b) {
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  if (b) for (var k in b) a[k] = b[k]
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}
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module.exports = function (sbot, source) {
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  var abouts = {/* link: {feed: name} */}
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  var msgs = {/* key: content */}
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  pull(
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    sbot.createLogStream({old: false}),
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    u.decryptMessages(sbot),
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    u.readableMessages(),
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    pull.drain(processMsg, function (err) {
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      if (err) console.error('about', err)
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    })
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  )
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  var getAboutInfo = asyncMemo(function (id, cb) {
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    var abt = abouts[id] = {}
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    var _err
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    var w = 1
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    if (ref.isMsg(id)) {
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      w++
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      sbot.get(id, function (err, value) {
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        if (err) {
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          console.error('about: missing message', id, err)
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          if (!--w) next()
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          return
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        }
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        u.decryptMessage(sbot, {key: id, value: value}, function (err, msg) {
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          if (err) console.error('decrypt failed', id, err)
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          else if (u.isMessageReadable(msg)) {
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            msgs[id] = msg && msg.value && msg.value.content
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          }
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          if (!--w) next()
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        })
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      })
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    }
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    pull(
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      sbot.backlinks ? sbot.backlinks.read({
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        reverse: true,
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        query: [{$filter: {
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          dest: id,
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          value: {
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            content: {
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              type: 'about'
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            }
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          }
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        }}]
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      }) : sbot.links({
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        rel: 'about',
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        values: true,
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        dest: id
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      }),
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      u.decryptMessages(sbot),
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      u.readableMessages(),
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      pull.drain(processMsg, function (err) {
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        _err = err
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        if (!--w) next()
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      })
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    )
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    function next() {
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      cb(_err, abt)
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    }
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  })
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  function processMsg(msg) {
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    var c = msg.value.content
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    if (!c) return
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    // handle receiving a message after receiving a link to it
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    if (msg.key in abouts) msgs[msg.key] = c
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    var target = c.about
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    if (!target) return
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    var abt = abouts[target]
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    if (!abt) return
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    var ab = abt[msg.value.author] || (abt[msg.value.author] = {})
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    for (var key in c) {
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      if (key === 'about' || key === 'type') continue
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      var val = c[key]
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      if (!val) delete ab[key]
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      else {
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        if (key === 'image' && typeof val === 'object' && val.link) {
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          val = val.link
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        }
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        ab[key] = val
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      }
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    }
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  }
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  function getAbout(dest, cb) {
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    if (!dest) return cb(null, {})
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    if (dest[0] === '#') return cb(null, {name: dest})
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    var target = dest.target || dest
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    getAboutInfo(target, function (err, info) {
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      if (err) return cb(err)
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      // order of preference: source, owner, any, msg
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      var ab = {}
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      mixin(ab, msgs[target])
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      for (var feed in info) mixin(ab, info[feed])
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      mixin(ab, info[dest.owner || dest])
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      mixin(ab, info[source])
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      if (!ab.name) ab.name = u.truncate(target, 20)
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      cb(null, ab)
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    })
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  }
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  getAbout.getName = function (id, cb) {
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    getAbout(id, function (err, about) {
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      cb(err, about && about.name)
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    })
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  }
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  return getAbout
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}
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