// This module provides an API layer above the 
// Data Canvas - Sense Your City API described at
// http://map.datacanvas.org/#!/data
define(["jquery", "lodash", "async"], function ($, _, async){

  // See API documentation at http://map.datacanvas.org/#!/data
  var API_URL = "http://sensor-api.localdata.com/api/v1/aggregations.csv",

      // List of all cities with available data.
      cities = ["San Francisco", "Bangalore", "Boston", "Geneva", "Rio de Janeiro", "Shanghai", "Singapore"],

      // The default parameters to pass into the API.
      defaultParams = {

        // Use averaging as the aggregation operator.
        op: "mean",

        // Include temperature only.
        fields: "temperature,light,airquality_raw,sound,humidity,dust"
      }

  // Fetches the latest data for a given city.
  function getDataForCity(options){
    return function(city, callback){
  
      // Get data for the last 24 hours.
      // 1000 milliseconds/second, 60 seconds/minute, 5 minutes
      var params = _.extend({
        "over.city": city
      }, options, defaultParams);
  
      // Use jQuery to fetch the data.
      // jQuery is used here rather than D3 because of its nice parameter syntax.
      $.get(API_URL, params, function(csv) {
  
        // Parse the CSV string.
        callback(null, d3.csv.parse(csv, function(d){
  
          // Parse ISO date strings into Date objects.
          // d.date = new Date(d.timestamp);
  
          // Parse strings into Numbers for numeric fields.
          // d.temperature = +d.temperature;
          //d.light = +d.light
          //d.airquality_raw = +d.airquality_raw
          //d.sound = +d.sound
          //d.humidity = +d.humidity
          //d.dust = +d.dust
  
          return d;
        }));
      });
    };
  }

  // Fetches the current temperature across all cities.
  return function getData(options, callback){
    async.map(cities, getDataForCity(options), function(err, results){
      callback(err, _.flatten(results));
    });
  }
});