Zig Zag with ATR

There are some ZigZag indicators (pivot points) with arbitrary values for top and botton. I want a indicator that define the top and the botton , using the ATR indicators. I want as parameters the number of ATR (Average True Range) and the number of bars. Thanks

I also want to be able to optimize those 2 parameters (number of atr and bars) using the expert advisor with the following rules:

1) sell on the top

2) buy on the top

Thanks