from-station-sync.js

var GeoUtil = require('./util/geo-util.js')

var OVERRIDE_MAX_DISTANCE = 1000
var LOCK_RELEASE_MARGIN = 100
var FROM_LOCKS = {
  none: 0,
  nearby: 1,
  manual: 2
}

function FromStationSync (nearbyStations, overrides, tripsSearch) {
  this.overrides = overrides
  this.nearbyStations = nearbyStations
  this.tripsSearch = tripsSearch
  this.fromLock = FROM_LOCKS.none
  this.fromlockDistance = 0
  this.fromChanged = this.fromChanged.bind(this)
  this.nearbyChanged = this.nearbyChanged.bind(this)
}

module.exports = FromStationSync

FromStationSync.prototype.start = function () {
  if (this.nearbyStations) {
    this.nearbyStations.bind('change:stations', this.nearbyChanged)
  }
  if (this.tripsSearch) {
    this.tripsSearch.bind('change:from', this.fromChanged)
  }
}

FromStationSync.prototype.stop = function () {
  if (this.nearbyStations) {
    this.nearbyStations.unbind('change:stations', this.nearbyChanged)
  }
  if (this.tripsSearch) {
    this.tripsSearch.unbind('change:from', this.fromChanged)
  }
}

FromStationSync.prototype.nearbyChanged = function (stations) {
  if (stations && stations.length > 0 && this.shouldChangeNearby()) {
    this.tripsSearch.from = (this.overrides)
      ? this.overrides.get(stations[0])
      : stations[0]
  }
}

FromStationSync.prototype.shouldChangeNearby = function () {
  if (!this.tripsSearch.from ||
      this.fromLock === FROM_LOCKS.none) { return true }
  if (this.fromLock === FROM_LOCKS.manual) { return false }
  return (
    GeoUtil.distance(
      this.nearbyStations.lastSearchLocation,
      this.tripsSearch.from.location
    ) > this.fromlockDistance + LOCK_RELEASE_MARGIN
  )
}

FromStationSync.prototype.fromChanged = function (station) {
  var nearbyStations = this.nearbyStations.stations
  if (!(station && nearbyStations && nearbyStations[0])) { return }
  var closestStation = nearbyStations[0]
  if (!closestStation.equals(station)) {
    var location = this.nearbyStations.lastSearchLocation
    var distance = GeoUtil.distance(location, station.location)
    var isNearby = this.nearbyStations.isAmongNearby(station)
    if (isNearby || distance <= OVERRIDE_MAX_DISTANCE) {
      this.fromLock = FROM_LOCKS.nearby
      this.fromlockDistance = distance
      if (this.overrides) {
        this.overrides.set(closestStation, station)
      }
    } else {
      this.fromLock = FROM_LOCKS.manual
    }
  } else {
    this.fromLock = FROM_LOCKS.none
    if (this.overrides) {
      this.overrides.set(closestStation, null)
    }
  }
}