var pull = require('pull-stream')
var many = require('pull-many')
var mfr = require('map-filter-reduce')

function all(stream, cb) {
  pull(stream, pull.collect(cb))
}

exports.needs = {
  sbot_links2: 'first',
  sbot_query: 'first'
}

exports.gives = {
  connection_status: true,
  signifier: true,
  signified: true,
}

/*
  filter(rel: ['mentions', prefix('@')]) | reduce(name: rel[1], value: count())
*/

var filter = {
  $filter: {
    rel: ["mentions", {$prefix: "@"}]
  }
}
var map = {
  $map: {
    name: ['rel', 1],
    id: 'dest',
    ts: 'ts',
  }
}

var reduce = {
  $reduce: {
    name: 'name',
    id: 'id',
    rank: {$count: true},
    ts: {$max: 'ts'}
  }
}

var filter2 = {
  $filter: {
    value: {
      content: {
        type: "about",
        name: {"$prefix": ""},
        about: {"$prefix": ""}
      }
    }
  }
}

var map2 = {
 $map: {
    name: ["value", "content", "name"],
    id: ['value', 'content', 'about'],
    ts: "timestamp"
  }
}

//union with this query...

var names = NAMES = []
function update(name) {
  var n = names.find(function (e) {
    return e.id == name.id && e.name == e.name
  })
  if(!n) {
    name.rank = 1
    //this should be inserted at the right place...
    names.push(name)
  }
  else
    n.rank = n.rank += (name.rank || 1)
}

var ready = false, waiting = []

var merge = {
  $reduce: {
    name: 'name',
    id: 'id',
    rank: {$sum: 'rank'},
    ts: {$max: 'ts'}
  }
}

function add_sigil(stream) {
  return pull(stream, pull.map(function (e) {
      if (e && e.id && e.name && e.id[0] !== e.name[0])
        e.name = e.id[0] + e.name
      return e
    })
  )
}

var queryNamedGitRepos = [
  {$filter: {
    value: {
      content: {
        type: "git-repo",
        name: {"$prefix": ""}
      }
    }
  }},
  {$map: {
    name: ["value", "content", "name"],
    id: ['key'],
    ts: "timestamp"
  }},
  reduce
]
exports.create = function (api) {

  var exports = {}
  exports.connection_status = function (err) {
    if(!err) {
      pull(
        many([
          api.sbot_links2({query: [filter, map, reduce]}),
          add_sigil(api.sbot_query({query: [filter2, map2, reduce]})),
          add_sigil(api.sbot_query({query: queryNamedGitRepos}))
        ]),
        //reducing also ensures order by the lookup properties
        //in this case: [name, id]
        mfr.reduce(merge),
        pull.collect(function (err, ary) {
          if(!err) {
            NAMES = names = ary
            ready = true
            while(waiting.length) waiting.shift()()
          }
        })
      )

      pull(many([
        api.sbot_links2({query: [filter, map], old: false}),
        add_sigil(api.sbot_query({query: [filter2, map2], old: false})),
        add_sigil(api.sbot_query({query: queryNamedGitRepos, old: false}))
      ]),
      pull.drain(update))
    }
  }

  function async(fn) {
    return function (value, cb) {
      function go () { cb(null, fn(value)) }
      if(ready) go()
      else waiting.push(go)
    }
  }

  function rank(ary) {
    //sort by most used, or most recently used
    return ary.sort(function (a, b) { return b.rank - a.rank || b.ts - a.ts })
  }

  //we are just iterating over the entire array.
  //if this becomes a problem, maintain two arrays
  //one of each sort order, but do not duplicate the objects.
  //that should mean the space required is just 2x object references,
  //not 2x objects, and we can use binary search to find matches.

  exports.signifier = async(function (id) {
    return rank(names.filter(function (e) { return e.id == id}))
  })

  exports.signified = async(function (name) {
    var rx = new RegExp('^'+name)
    return rank(names.filter(function (e) { return rx.test(e.name) }))
  })

  return exports
}