Dynamic Trailing Stop

  I am trying to script a dynamic trailing stop on a daily chart. I can plot the current price with a horizontal line and plot a second line to follow as the price rises and falls. What I can’t figure out is how to get the second line to stop when the current price line falls. Any help would be greatly appreciated. Here is the code I have written so far:

input StopDiff = 00.00;

def Diff = StopDiff;

def vClose = close;

def nan = double.NaN;

def highestClose = HighestAll(if IsNaN(vClose[-1]) then highest (vClose) else nan);

plot hc = highestClose;

hc.SetPaintingStrategy(PaintingStrategy.Horizontal);

hc.SetDefaultColor(Color.DARK_GREEN);

hc.SetLineWeight(2);

hc.HideBubble();

hc.HideTitle();

def TrailingStop = if high<=(hc) then (hc)-Diff else high – diff;

plot TS = hc-Diff;

TS.SetPaintingStrategy(PaintingStrategy.Horizontal);

TS.SetDefaultColor(Color.Blue);

TS.SetLineWeight(2);