A label list implementation for webcompat.com

labels.js

/**
* A LabelList is a list of labels. It takes care of all namespace
* prefixing and unprefixing, so that the rest of the app doesn't
* ever need to worry about those details. Just pass in a list
* of labels from the server or a URL.
*/
issues.LabelList = Backbone.Model.extend({
  initialize: function() {
    this.set('namespaceRegex', /(browser|closed|os|status)-(.+)/i);
    this.set('allLabelsURL', '/api/issues/labels'); // see "need a complete list" below
    // if we're initialized with {labels:array-of-objects}
    var inputLabelData = this.get('labels');
    this.set('labels', []);
    if(inputLabelData) {
      // If we have an array, process labels
      this.parse(inputLabelData);
    } else {
      // We default to making a list of all labels if lacking other data
      if(! this.get('url')) {
        this.set('url', this.get('allLabelsURL'));
      }
      // If we have an URL, start a fetch
      var headersBag = {headers: {'Accept': 'application/json'}};
      this.fetch(headersBag); // This will trigger parse()
    }
    // We allow updating 'labels', but want to make sure
    // other internal details are kept sync'ed..
    this.on('change:labels', function(){
      this.set('labelsArray', _.pluck(this.get('labels'), 'name'));
    });
    // We need a complete list of labels for certain operations,
    // especially namespace mapping. If the list we're handling
    // doesn't happen to contain all the labels initially, it
    // can't get prefixing/unprefixing right when labels in previously
    // unseen namespaces are added in their local name form.
    if(this.get('url') === this.get('allLabelsURL')) {
      this.set('allLabels', this);
    } else {
      this.set('allLabels', new issues.LabelList({url:this.get('allLabelsURL')}));
    }
  },
  parse: function(labelsArray){
    var list = [];
    var namespaceMap = {"ns2local":{}, "local2ns":{}};
    for(var i = 0, matches; i < labelsArray.length; i++){
      matches = labelsArray[i].name.match(this.get('namespaceRegex'));
      if(matches) {
        namespaceMap.local2ns[matches[2]] = matches[1];
        namespaceMap.ns2local[matches[0]] = matches[2];
        list[i] = {
          'name': matches[2],
          'url': labelsArray[i].url,
          'color': labelsArray[i].color,
         };
      }else {
        list[i] = labelsArray[i];
      }
    };
    this.set('labels', list);
    this.set('namespaceMap', namespaceMap);
  },
  // toLocal takes a repository label name and maps it
  // to the unprefixed local form. Also handles an array
  // of label names (Note: not arrays of objects)
  toLocal: function(input) {
    var all = this.get('allLabels');
    if (typeof input === 'string') {
      return all.get('namespaceMap').ns2local[input] || input;
    } else {
      return input.map(function(label){return this.toLocal(label);}.bind(all));
    }
  },
  // toNamespaced takes a local label name and maps it
  // to the prefixed repository form. Also handles an array
  // of label names (Note: not arrays of objects)
  toNamespaced: function (input) {
    var all = this.get('allLabels');
    if (typeof input === 'string') {
      return all.get('namespaceMap').local2ns[input] + '-' + input || input;
    } else {
      return input.map(function(label){return this.toNamespaced(label);}.bind(all));
    }
  },
  url: function() {
    return this.get('url');
  },
  // To save the model to the server, we need to make
  // sure we apply the prefixes the server expects
  save: function() {
    var all = this.get('allLabels');
    var labelsArray = this.get('labelsArray');
    var saveLabels = all.toNamespaced(labelsArray);
    var url = this.url();
    // We create a new model with only the labels we
    // want to send to the server to save
    var saver = new (Backbone.Model.extend({
      url:function(){return url;}
    }))({labels:saveLabels});
    saver.save();
  }
});

toNamespaced might be better named "toPrefixed" and toLocal -> toUnprefixed ?
("Local name" and "namespace" terminology is XMLish)

toNamespaced() (by any name) should never apply a namespace to a label that has namespace prefix already - simply because there would be no match in the local2ns object. But this should be tested.