service pattern example

gistfile1.txt

/* global angular, google */

angular.module('app')
.service('router', ['$q', function($q){
    var router = new google.maps.DirectionsService();

    this.getRoutePromise = function(_origin, _destination) {
      var deferred = $q.defer();

      var request = {
        origin: _origin,
        destination: _destination,
        travelMode: google.maps.TravelMode.TRANSIT,
        provideRouteAlternatives: true
      };

      if (typeof request.origin == 'undefined' || typeof request.destination == 'undefined') {
        // if origin or destination not defined, reject promise
        deferred.reject('UNDEFINED_ENDPOINTS');
      } else {
        // origin and destination are well defined
        router.route(request, function(result, status) {
          if (status != google.maps.DirectionsStatus.OK) {
            // if google maps gave bad response, reject promise
            deferred.reject(status);
          } else {
            // if google maps gave OK response, convert routes to promise
            var routes = [];
            angular.forEach(
              result.routes,
              function(route) {
                this.push(route.legs[0]);
              },
              routes);
            deferred.resolve(routes);
          }
        });
      }

      return deferred.promise;

      ///////////////////////////////////
      //// HOW TO USE THIS PROMISE   ////
      ///////////////////////////////////
      // Use promise.then and promise.catch to add callbacks:
      // var promise = router.getRoutePromise(origin,dest);
      // promise.then(resolveCallback).catch(rejectCallback);
      //
      // rejectCallback should expect a string which is
      // either 'UNDEFINED_ENDPOINTS' or one of
      // google.maps.DirectionsStatus.
      //
      // resolveCallback should expect an array of google
      // maps route objects, which looks like this (only
      // relevant keys shown):
      // route = {
      //   start_address (actual address, formatted str),
      //   start_location: { k (lat), B (long) },
      //   end_address (actual address, formatted str),
      //   end_location: { k (lat), B (long) },
      //   departure_time: { text ('00:00am'), time_zone (str), value (Date) },
      //   arrival_time: { text ('00:00am'), time_zone (str), value (Date) },
      //   distance: { text ('00.0 mi'), value (Int in meters) },
      //   duration: { text ('0 hours 00 mins'), value (Int in seconds) },
      //   steps (array of step objects)
      // }
      //
      // ...and the step objects are similar:
      // step = {
      //   start_location: { k (lat), B (long) },
      //   end_location: { k (lat), B (long) },
      //   distance: { text ('00.0 mi'), value (Int in meters) },
      //   duration: { text ('0 hours 00 mins'), value (Int in seconds) },
      //   travel_mode: (google.maps.TravelMode)
      //   instructions (description of step, formatted str)
      //   steps (array of step objects)
      // }
      //
      // The steps array in the result object contains a
      // step for each subsequent mode of transportation.
      // Each of these steps has its own steps array which
      // contains turn by turn directions. The instructions
      // string describes each step and matches its
      // specificity.
    }
}]);