git ssb

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var compare   = require('typewiselite')
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var pull      = require('pull-stream')
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function isString (s) {
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  return 'string' === typeof s
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}
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function all (stream) {
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  return function (cb) {
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    pull(stream, pull.collect(cb))
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  }
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}
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module.exports = function (db) {
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  return function (opts, cb) {
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    if(isString(opts)) opts = {key: opts}
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    if(!opts) throw new Error('opts *must* be object')
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    var key = opts.id || opts.key
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    var depth = opts.depth || Infinity
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    var seen = {}
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    //filter a list of rel, used to avoid 'branch' rel in patchwork,
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    //which causes messages to be queried twice.
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    var n = 1
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    var msgs = {key: key, value: null}
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    db.get(key, function (err, msg) {
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      msgs.value = msg
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      if (err && err.notFound)
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        err = null // ignore not found
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      done(err)
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    })
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    related(msgs, depth)
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    function related (msg, depth) {
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      if(depth <= 0) return
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      if (n<0) return
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      n++
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      all(db.links({dest: msg.key, rel: opts.rel, keys: true, values:true, meta: false, type:'msg'}))
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      (function (err, ary) {
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        if(ary && ary.length) {
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          msg.related = ary = ary.sort(function (a, b) {
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            return compare(a.value.timestamp, b.value.timestamp) || compare(a.key, b.key)
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          }).filter(function (msg) {
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            if(seen[msg.key]) return
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            return seen[msg.key] = true
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          })
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          ary.forEach(function (msg) { related (msg, depth - 1) })
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        }
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        done(err)
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      })
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    }
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    function count (msg) {
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      if(!msg.related)
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        return msg
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      var c = 0
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      msg.related.forEach(function (_msg) {
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        if(opts.parent) _msg.parent = msg.key
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        c += 1 + (count(_msg).count || 0)
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      })
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      if(opts.count) msg.count = c
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      return msg
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    }
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    function done (err) {
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      if(err && n > 0) {
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        n = -1
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        return cb(err)
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      }
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      if(--n) return
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      cb(null, count(msgs))
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    }
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  }
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}
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