(function ($, undefined) {
  $.widget('ui.dragslider', $.ui.slider, {
    options: $.extend({}, $.ui.slider.prototype.options, { rangeDrag: false }),

    _create: function () {
      $.ui.slider.prototype._create.apply(this, arguments);
      this._rangeCapture = false;
    },

    _mouseCapture: function (event) {
      var o = this.options;

      if (o.disabled) return false;

      if (event.target == this.range.get(0) && o.rangeDrag == true && o.range == true) {
        this._rangeCapture = true;
        this._rangeStart = null;
      } else {
        this._rangeCapture = false;
      }

      $.ui.slider.prototype._mouseCapture.apply(this, arguments);

      if (this._rangeCapture == true) {
        this.handles.removeClass('ui-state-active').blur();
      }

      return true;
    },

    _mouseStop: function (event) {
      this._rangeStart = null;
      return $.ui.slider.prototype._mouseStop.apply(this, arguments);
    },

    _slide: function (event, index, newVal) {
      if (!this._rangeCapture) {
        return $.ui.slider.prototype._slide.apply(this, arguments);
      }

      if (this._rangeStart == null) {
        this._rangeStart = newVal;
      }

      var oldValLeft = this.options.values[0],
        oldValRight = this.options.values[1],
        slideDist = newVal - this._rangeStart,
        newValueLeft = oldValLeft + slideDist,
        newValueRight = oldValRight + slideDist,
        allowed;

      if (this.options.values && this.options.values.length) {
        if (newValueRight > this._valueMax() && slideDist > 0) {
          slideDist -= newValueRight - this._valueMax();
          newValueLeft = oldValLeft + slideDist;
          newValueRight = oldValRight + slideDist;
        }

        if (newValueLeft < this._valueMin()) {
          slideDist += this._valueMin() - newValueLeft;
          newValueLeft = oldValLeft + slideDist;
          newValueRight = oldValRight + slideDist;
        }

        if (slideDist != 0) {
          newValues = this.values();
          newValues[0] = newValueLeft;
          newValues[1] = newValueRight;

          // A slide can be canceled by returning false from the slide callback
          allowed = this._trigger('slide', event, {
            handle: this.handles[index],
            value: slideDist,
            values: newValues,
          });

          if (allowed !== false) {
            this.values(0, newValueLeft, true);
            this.values(1, newValueRight, true);
          }
          this._rangeStart = newVal;
        }
      }
    },

    /*
    //only for testing purpose
    value: function(input) {
        console.log("this is working!");
        $.ui.slider.prototype.value.apply(this,arguments);
    }
    */
  });
})(jQuery);