git ssb

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'use strict'
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var G = require('graphreduce')
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var F = require('ssb-friends/alg')
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var Reduce = require('flumeview-reduce')
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var pull = require('pull-stream')
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var FlatMap = require('pull-flatmap')
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var ref = require('ssb-ref')
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exports.name = 'sameAs'
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exports.version = require('./package.json').version
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exports.manifest = {
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  get: 'async',
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  stream: 'source'
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}
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exports.init = function (sbot, config) {
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  var g = {}
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  var index = sbot._flumeUse('sameAs', Reduce(2, function (graph, rel) {
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    if (!graph) graph = {}
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    if (rel) {
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      if (ref.isFeed(rel.from) && ref.isFeed(rel.to)) {
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        var outgoing = G.get(graph, rel.from, rel.to) || []
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        var incoming = G.get(graph, rel.to, rel.from) || []
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        incoming[1] = outgoing[0] = rel.value
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        G.addEdge(graph, rel.from, rel.to, outgoing)
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        G.addEdge(graph, rel.to, rel.from, incoming)
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      } else if (rel.localClaims) {
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        G.eachEdge(rel.localClaims, (from, to, value) => {
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          var outgoing = G.get(graph, from, to) || []
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          var incoming = G.get(graph, to, from) || []
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          outgoing[2] = incoming[2] = value
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          G.addEdge(graph, from, to, outgoing)
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          G.addEdge(graph, to, from, incoming)
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        })
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      }
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    }
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    return graph
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  }, function (data) {
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    if (isSameAsMsg(data)) {
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      var author = data.value.author
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      var contact = data.value.content.contact
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      var sameAs = data.value.content.sameAs
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      if (typeof sameAs === 'boolean') {
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        return {
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          from: author,
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          to: contact,
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          value: sameAs
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        }
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      } else if (data.value.content.sameAs instanceof Object && data.value.author === sbot.id) {
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        return {
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          localClaims: {
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            [contact]: sameAs
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          }
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        }
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      }
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    }
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  }, null, g))
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  function get (id) {
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    var graph = index.value.value
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    return F.reachable(graph, id, {
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      initial: undefined, reduce, expand
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    })
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  }
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  function createSameAsStream (opts) {
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    opts = opts || {}
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    var sameAs = {}
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    return pull(
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      index.stream(opts),
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      pull.filter(),
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      FlatMap(function (value) {
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        var result = []
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        var graph = index.value.value
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        // TODO: this has to traverse the entire graph, should use the subset when realtime update
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        G.eachEdge(graph, (from, to, values) => {
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          var sameAs = get(from)
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          // clear out unreachable keys
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          for (let dest in sameAs[from]) {
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            if (sameAs[dest] == null && sameAs[from] !== false) {
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              update(from, dest, false)
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            }
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          }
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          // update reachable
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          for (let dest in sameAs) {
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            if (sameAs[dest] != null && from !== dest) {
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              update(from, dest, sameAs[dest])
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            }
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          }
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        })
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        return result
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        function update (from, to, value) {
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          var lastValue = G.get(sameAs, from, to)
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          if (lastValue !== value && !(lastValue == null && value === false)) {
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            G.addEdge(sameAs, from, to, value)
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            result.push({from, to, value})
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          }
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        }
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      })
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    )
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  }
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  // REPLICATION
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  if (sbot.replicate) {
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    // probably should sit on ssb-friends createFriendStream and then check emitted values for sameAs
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    // TODO: add sameAs peers to replicate map
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  }
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  return {
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    get: function (opts) {
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      return get(opts.id)
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    },
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    stream: createSameAsStream
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  }
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}
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function isSameAsMsg (msg) {
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  return msg.value.content.type === 'contact' && ref.isFeed(msg.value.content.contact) && 'sameAs' in msg.value.content
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}
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function getValue (values) {
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  // mutual sameAs
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  if (values[0] && values[1]) {
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    return true
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  }
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  // one party disagrees
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  if (values[0] === false || values[1] === false) {
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    return false
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  }
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  // partial with
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  if ((values[0] || values[1]) && values[2]) {
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    return true
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  }
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}
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function reduce (target, source, value) {
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  if (target !== false) {
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    target = getValue(value)
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  }
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  return target
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}
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function expand (value) {
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  return value != null
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}
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