var Reduce = require('./reduce')
var pull = require('pull-stream')

module.exports = function (sbot, opts, cb) {
  if("string" == typeof opts)
    opts = {id: opts, private: false}
  var id = opts.id
  sbot.get(opts, function (err, msg) {
    if(err) return cb(err)
    var seen = {}

    if(msg.content.type !== 'gathering')
      return cb(new Error('not a gathering, was:'+msg.content.type))
    var root = {key:id, value: msg}
    seen[id] = true
    console.log('gathering', opts)
    pull(
      sbot.links({
        dest: id, values: true,
        rel: opts.replies ? undefined : 'about'
      }),
      pull.filter(function (data) {
        var type = data.value.content.type
        //exclude backlinking posts, except replies
        if(type == 'post' && data.value.content.root != id)
          return
        //the root message is type gathering
        //I really think the "about" message is heavily overloaded
        if(type !== 'gathering' && type !== 'about' && type !== 'post')
          return

        if(seen[data.key]) return false
        return seen[data.key] = true
      }),
      pull.collect(function (err, ary) {
        if(err) return cb(err)
        ary.unshift(root)
        var r = Reduce(ary)
        cb(null, r)
      })
    )
  })
}