var FlumeViewLevel = require('flumeview-level')
var pull = require('pull-stream')
var cat = require('pull-cat')

function map(msg) {
  var author = msg.value.author
  var ts = msg.value.timestamp
  if (!ts) return []

  var day = ts / 86400000
  var week = day / 7
  var month = day / 30.43666666666666666666 // 365.24 / 12

  // record that the feed author was active this day, week and month
  return [
    ['day', Math.floor(day), author],
    ['week', Math.floor(week), author],
    ['month', Math.floor(month), author]
  ]
}

var validSeries = {
  day: true,
  week: true,
  month: true
}

function groupByIds(opts) {
  var prevTime, ids
  var listIds = Boolean(opts.ids)
  return pull.map(function (indexed) {
    var key = indexed.key
    var id = key[2]
    var time = key[1]
    if (time === prevTime) {
      // count unique feed ids in the time interval
      if (listIds) ids.push(id)
      else ids++
    } else {
      var ret = prevTime && {time: prevTime, ids: ids}
      prevTime = time
      ids = listIds ? [id] : 1
      return ret
    }
  })
}

exports.name = 'activity'
exports.version = '0.0.0'
exports.manifest = {
  read: 'source'
}

exports.init = function (sbot, config) {
  var version = 2
  var deleteTheDb = false
  var view = FlumeViewLevel(deleteTheDb, map)
  var activity = sbot._flumeUse('activity' + version, view)

  return {
    read: function (opts) {
      if (!opts) return pull.error(new TypeError('Missing opts'))
      var series = opts.series
      if (!series) return pull.error(new TypeError('Missing opts.series'))
      if (!validSeries[series]) return pull.error(new TypeError('Invalid series'))
      var readOpts = {}
      var groupOpts = {
        ids: opts.ids
      }
      for (var k in opts) {
        if (k === 'series' || k === 'ids') continue
        var value = opts[k]
        // transform key ranges from query opts into internal key ranges
        if (k === 'gt' || k === 'gte') value = [series, value, null]
        else if (k === 'lt' || k === 'lte') value = [series, value, undefined]
        readOpts[k] = value
      }
      if (!readOpts.gt && !readOpts.gte) readOpts.gt = [series, null, null]
      if (!readOpts.lt && !readOpts.lte) readOpts.lt = [series, undefined, undefined]
      return pull(
        // add object at end of stream to make the last group-by interval work
        cat([activity.read(readOpts), pull.once({key: []})]),
        groupByIds(groupOpts),
        pull.filter(Boolean)
      )
    }
  }
}