/src/models/sitecollection.js

define([
  'config!',
  'underscore',
  'models/livecollection',
  'models/sitemodel',
  'models/thumbnailjobcollection',
  'lib/translatekeys',
  'lib/template',
  'lib/urlhelper'
], function(
  config, util, LiveCollection,
  SiteModel, ThumbnailJobCollection,
  translateKeys,
  template,
  URLHelper
){
  
  var SiteCollection = LiveCollection.extend({
    model: SiteModel,

    resultAttributeMap: {
      // we want attributes.primaryType to be populated with the value of attributes.type
      'primaryType': 'type',
      'url': 'uri',
      'thumbnailKey': 'thumbnail_key',
      'thumbnailStatus': 'thumbnail_status'
    },
    
    initialize: function (models, options) {
      // Mix in some default options.
      options = options || {};
      
      // Create a new URL helper with defaults.
      var helper = new URLHelper({
        // Set a default template for URLHelper
        template: '{ base }{ path }{ query }',
        // Configure some default token values for URLHelper
        tokens: {
          base: config.apiRoot,
          path: 'top'
        }
      });
      // Update helper with any config passed in through options.
      helper.update(options.tokens, options.query);
      
      // Point this.url to URLHelper's url method.
      this.url = util.bind(helper.url, helper);
      
      // keep optional mapping of item data property keys to model properties
      if(options.attributeMap){
        this.attributeMap = util.defaults(this.attributeMap || {}, options.attributeMap);
      }

      // Any time a new site collection is fetched, start a new
      // thumbnail job collection for it.
      this.bind('reset', this.startThumbnailJob, this);
      this.bind('add', this.startThumbnailJob, this);
    },
    
    startThumbnailJob: function () {
      var thumbnailJob = this.thumbnailJob;
      
      if (
        // Don't start a job if the ID comes back null
        !this.thumbnailJobID ||
        (
          // Don't start the same job twice.
          thumbnailJob &&
          thumbnailJob.jobID === this.thumbnailJobID
        )
      ) return;

      // Create a new thumbnail job collection. Set the ID of the
      // thumbnail job (which ThumbnailJobCollection turns into a URL).
      var thumbnailJobCollection = new ThumbnailJobCollection({}, {
        jobID: this.thumbnailJobID
      });

      // When the thumbnails job comes back populated, update siteModels
      // in this collection.
      thumbnailJobCollection.bind(
        'reset',
        this.updateModelsWithThumbnails,
        this
      );

      // Go get 'em tiger.
      thumbnailJobCollection.pollUntilFinishedProcessing();
      
      this.thumbnailJob = thumbnailJobCollection;
    },
    
    updateModelsWithThumbnails: function (thumbnailJobCollection) {
      var siteCollection = this;
      siteCollection.each(function (site) {
        // Get the site's thumbnail key...
        var thumbKey = site.get('thumbnailKey'),
            siteThumbStatus = site.get('thumbnailStatus'),
            siteThumbUrl = site.get('thumbnailUrl'),
            // Get the thumbnail record by its ID (same as thumbnail key)
            thumbModel = thumbnailJobCollection.get(thumbKey),
            thumbStatus = thumbModel ? thumbModel.get('status') : null,
            thumbUrl = thumbModel ? thumbModel.src() : null,
            update = {};
        
        // If status has changed or is new...
        if (siteThumbStatus !== thumbStatus)
          update.thumbnailStatus = thumbStatus;
        
        // If the URL is changed or new...
        if (siteThumbUrl !== thumbUrl)
          update.thumbnailUrl = thumbUrl;
        
        // Update the site with changes. Will fire an event
        // on the site record.
        if (!util.isEmpty(update)) site.set(update);
      });
    },

    // Get the value of an property in an object, optionally using a dot-path (some.deep.object)
    _getObject: function(name, obj){
      // TODO: could be a util/lang helper - not really class or collection-specific
      var parts = name.split('.'), 
          pname = null;
          
      while((pname = parts.shift())){
        obj = obj[pname];
      }
      return obj;
    },

    // _setValue: function(name, value, obj) {
    //   
    // },

    _applyAttributeMap: function(data, attributeMap){
      // translate data
      // could be a util/lang helper - not really class or collection-specific
      var mapping = attributeMap || this.attributeMap, 
          getObject = this._getObject;

      // { 'alias': 'source' }
      util.each(mapping, function(name, alias, map){
        if(name in data) {
          data[alias] = name.indexOf(".") > -1 ? 
              getObject(name, data) : 
              data[name]
          ;
          // could *replace* by deleting the original key, but we should deep-clone the data at that point
        }
      });
      return data;
    }, 

    // Backbone.Collection's default parse method passes sync (xhr) results
    // directly to Collection.set. We're defining a custom parse
    // implementation that massages data from our JSON API into
    // a Backbone.Model-compatible format.
    //
    // Sample return data:
    //    {
    //      "results": [
    //        {
    //          "sortindex": 10,
    //          "title": "Join.me",
    //          "uri": "https://join.me/",
    //          "thumbnail_key": "...",
    //          "thumbnail_status": "processing",
    //          "type": "suggestion",
    //          "id": "...",
    //          "types": ["suggestion"]
    //        },
    //        ...
    //      ],
    //      "success": true,
    //      "thumbnails_job": "..."
    //    }
    parse: function (resp, xhr) {
      // If the API considers this a success (different from HTTP response)...
      this.isSuccess = resp.success;

      this.thumbnailJobID = resp.thumbnails_job;

      // If API success, translate results to new format and
      // pass back. Otherwise, pass empty array.
      if(resp.success) {
        resp = util.map(resp.results, function(result) {
          return this._applyAttributeMap(result, this.resultAttributeMap);
        }, this);
      } else {
        resp = [];
      }
      return resp;
    }
  });
  return SiteCollection;
});