var Storage = (function() {
  var uniqueId = 0;
  function Storage() {}

  Storage.prototype.add = function(item) {
    var id = this.generateId()
      , data = this._toJSON(item);

    localStorage[id] = data;
  };

  Storage.prototype.generateId = function() {
    return ++uniqueId;
  };

  Storage.prototype.reset = function() {
    uniqueId = 0;
  };

  Storage.prototype._toJSON = function(items) {
    return JSON.stringify(items);
  };

  Storage.prototype._fromJSON = function(json) {
    return JSON.parse(json);
  };

  return Storage;
})();

window.Storage = Storage;