app.js

(function() {

  return {
    events: {
      'app.activated':'onAppActivated'
    },

    onAppActivated: function(app) {
      if (app.firstLoad){
        _.defer(this.initialize.bind(this));
      }
    },

    initialize: function() {
      var value = this.execRegexOnFields(),
          key = helpers.fmt('custom_field_%@',this.setting('result_field'));

      if (value && _.isEmpty(this.ticket().customField(key))){
        this.ticket().customField(key, value);
      }

    },

    execRegexOnFields: function(){
      var value = '';

      var ticket = this.containerContext().ticket;
      var first_comment = _.last(ticket.comments);
      ticket.description = first_comment.value;

      _.each(this.fields(), function(field){
        if (!_.isEmpty(this.containerContext().ticket[field]) &&
           _.isEmpty(value)){
          value = (this.containerContext().ticket[field].match(this.regexp()) || [])[1] || "";
        }
      }, this);

      return value;
    },

    fields: function(){
      return _.compact(this.setting('fields').split(','));
    },

    regexp: _.memoize(function(){
      return this.setting('regexp');
    })
  };

}());