location-sort.coffee

#= require jquery
#= require jquery-sort

$locationsContainer = $('#locations')
locationsData = $locationsContainer.data('locations')
currentCoords = latitude: 0, longitude: 0
locations = []
firstRun = true

if typeof (Number::toRad) is 'undefined'
  Number::toRad = ->
    this * Math.PI / 180

getDistance = (start, end, decimals) ->
  decimals = decimals or 2
  earthRadius = 6371 # km
  lat1 = parseFloat(start.latitude)
  lat2 = parseFloat(end.latitude)
  lon1 = parseFloat(start.longitude)
  lon2 = parseFloat(end.longitude)
  dLat = (lat2 - lat1).toRad()
  dLon = (lon2 - lon1).toRad()
  lat1 = lat1.toRad()
  lat2 = lat2.toRad()
  a = Math.sin(dLat / 2) * Math.sin(dLat / 2) + Math.sin(dLon / 2) * Math.sin(dLon / 2) * Math.cos(lat1) * Math.cos(lat2)
  c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a))
  d = earthRadius * c
  Math.round(d * Math.pow(10, decimals)) / Math.pow(10, decimals)

success = (position) ->
  console.log 'got location', position
  if currentCoords.latitude isnt position.coords.latitude and currentCoords.longitude isnt position.coords.longitude
    currentCoords = position.coords
    sortLocationsByDistance()
    buildButtons()
    sortButtons()

error = (error) ->
  buildButtons()

options =
  enableHighAccuracy: false
  maximumAge: 30000
  timeout: 25000

sortLocationsByDistance = ->
  locations = for location in locationsData
    location.distance = getDistance(location, currentCoords, 4)
    location.distance_human = location.distance + 'km'
    location

buildButtons = ->
  if firstRun
    html = for location in locations
      buildButton(location)
    $locationsContainer.html(html)
    firstRun = false
  else
    for location in locations
      if ($location = $("location-#{location.id}")).length
        $location.data('distance', location.distance)
        $location.find('.distance').text(location.distance_human)

buildButton = (location) ->
  html = """
    <button class="category-#{location.category}" id="location-#{location.id}" data-distance="#{location.distance}">
      <span class="distance">#{location.distance_human}</span>
      <span class="label">#{location.name}</span>
    </button>
  """

sortButtons = ->
  $locationsContainer.children().sortElements (a, b) ->
    if $(a).data('distance') > $(b).data('distance') then 1 else -1

if navigator.geolocation
  $locationsContainer.text 'Finding location...'
  navigator.geolocation.watchPosition(success, error, options)