How to add tooltip in fl chart flutter

Question

I am using fl chart but I want when user hover on the chart a tooltip should be displayed where value of that bar should be displayed. How can I do this? Here is my code

barTouchData: BarTouchData(
              touchTooltipData: BarTouchTooltipData(
                tooltipBgColor: Colors.grey,
                getTooltipItem: (a, b, c, d) => null,
              ),
              enabled: true,
              touchCallback: (event, response) {
                if (response != null &&
                    response.spot != null &&
                    event is FlTapUpEvent) {
                  setState(() {
                    final x = response.spot!.touchedBarGroup.x;
                    final isShowing = showingTooltip == x;
                    if (isShowing) {
                      showingTooltip = -1;
                    } else {
                      showingTooltip = x;
                    }
                  });
                }
              },
              mouseCursorResolver: (event, response) {
                return response == null || response.spot == null
                    ? MouseCursor.defer
                    : SystemMouseCursors.click;
              }