translink.js

var Model = require("./model.js");
var Departure = Model.Departure;
var BusStop = Model.BusStop;

var method = "GET";
var api = (function () {
  "use strict";
  var url = "http://api.translink.ca";
  var apiKey = "0GKoVlC6TgpNJJNRjZ1r";

  function getWithApiKey(entry, routes, fields) {
    fields.apiKey = apiKey;
    routes.unshift("rttiapi", "v1", entry);
    var routesStr = routes.map(function (v) {
      return "/" + v;
    }).join("");
    return url + routesStr + "?" + Object.keys(fields).map(function (arg) {
        return arg + "=" + fields[arg];
      }).join("&");
  }

  return {
    stops: "stops",
    buses: "buses",
    route: "routes",
    getWithApiKey: getWithApiKey
  };
})();

/**
 * Get nearby stops
 * @param {number} lat
 * @param {number} long
 * @param {number} radius
 * @param {Function} callbackSuccess
 * @param {Function} callbackFail
 */
function getStops(lat, long, radius, callbackSuccess, callbackFail) {
  "use strict";
  var url = api.getWithApiKey(api.stops, [], {
    lat: formatLocation(lat),
    long: formatLocation(long),
    radius: radius
  });

  request(url, callback, callbackError);

  function callback(xmlRes) {
    callbackSuccess(parseStopsXML(xmlRes));
  }

  function formatLocation(loc) {
    return Math.floor(loc * 1000000) / 1000000;
  }

  function callbackError(xmlRes) {
    var xmlDoc = xmlRes.responseXML;
    if (xmlDoc) {
      console.log("Response: " + xmlRes.responseText);
      callbackFail(xmlRes);
    } else {
      throw new Error("Cant parse" + xmlRes.responseText);
    }
  }

  function parseStopsXML(xmlRes) {
    var xmlDoc = xmlRes.responseXML;
    var stopsXML = xmlDoc.getElementsByTagName("Stop");
    var stops = [];
    var fnEvalRoute = function (route) {
      stops.push(new BusStop(
        elementVal(element, "StopNo"),
        elementVal(element, "Name"),
        route,
        elementVal(element, "Distance")
      ));
    };
    console.log("Got " + stopsXML.length + " stops!");
    for (var i = 0; i < stopsXML.length; i++) {
      var element = stopsXML.item(i);
      elementVal(element, "Routes").split(", ").forEach(fnEvalRoute);
    }
    return stops;
  }
}

/**
 * Get the next bus schedule, route is optional
 * @param {BusStop} busStop
 * @param {Function} callbackSuccess
 * @param {Function} callbackFail
 */
function getNextBus(busStop, callbackSuccess, callbackFail) {
  "use strict";
  var args = {count: 3};
  if (busStop.route) {
    args = { routeNo: busStop.route, count: 3};
  }
  var url = api.getWithApiKey(api.stops, [busStop.number, "estimates"], args);

  request(url, callback, callbackError);

  function callback(xmlRes) {
    callbackSuccess(parseNextBusXML(xmlRes));
  }

  function callbackError(xmlRes) {
    var xmlDoc = xmlRes.responseXML;
    if (xmlDoc) {
      console.log("Response: " + xmlRes.responseText);
      callbackFail(xmlRes);
    } else {
      throw new Error("Cant parse" + xmlRes.responseText);
    }
  }

  function parseNextBusXML(xmlRes) {
    var xmlDoc = xmlRes.responseXML;
    var stopsXML = xmlDoc.getElementsByTagName("NextBus");
    var stops = [];
    console.log("Got " + stopsXML.length + " buses!");
    for (var i = 0; i < stopsXML.length; i++) {
      var element = stopsXML.item(i);
      var routeNumber = elementVal(element, "RouteNo");
      var routeXML = element.getElementsByTagName("Schedule");
      console.log("Got " + routeXML.length + " schedules for " + routeNumber + "!");
      for (var j = 0; j < routeXML.length; j++) {
        var scheduleElement = routeXML.item(j);
        stops.push(new Departure(
          routeNumber,
          elementVal(scheduleElement, "Destination"),
          elementVal(scheduleElement, "ExpectedCountdown"),
          busStop
        ));
      }
    }
    return stops;
  }
}

function elementVal(elementToSearch, str) {
  "use strict";
  if (elementToSearch) {
    var children = elementToSearch.getElementsByTagName(str);
    if (children.length) {
      return children.item(0).textContent;
    }
  }
  console.log("Error processing:" + elementToSearch.textContent);
  return "";
}

function request(url, callbackSuccess, callbackFail) {
  "use strict";
  console.log("Requesting: " + url);
  var request = new XMLHttpRequest();
  request.onload = function () {
    if (request.readyState === request.DONE && request.status === 200) {
      callbackSuccess(this);
    } else {
      callbackFail(this);
    }
  };
  request.open(method, url);
  request.send();
}

module.exports = {
  getStops: getStops,
  getNextBus: getNextBus
};